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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
0704.3401 | Dieter Bauer | M. Kundu, S.V. Popruzhenko, D. Bauer | Harmonic Generation from Laser-Irradiated Clusters | 4 pages, ReVTeX4 | null | 10.1103/PhysRevA.76.033201 | null | physics.plasm-ph physics.optics | null | The harmonic emission from cluster nanoplasmas subject to short, intense
infrared laser pulses is analyzed by means of particle-in-cell simulations. A
pronounced resonant enhancement of the low-order harmonic yields is found when
the Mie plasma frequency of the ionizing and expanding cluster resonates with
the respective harmonic frequency. We show that a strong, nonlinear resonant
coupling of the cluster electrons with the laser field inhibits coherent
electron motion, suppressing the emitted radiation and restricting the spectrum
to only low-order harmonics. A pump-probe scheme is suggested to monitor the
ionization dynamics of the expanding clusters.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 16:08:53 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Kundu",
"M.",
""
],
[
"Popruzhenko",
"S. V.",
""
],
[
"Bauer",
"D.",
""
]
] |
0704.3402 | Pedro Coronel | Pedro Coronel and Helmut B\"olcskei | Diversity-Multiplexing Tradeoff in Selective-Fading MIMO Channels | To be presented at IEEE Int. Symp. Inf. Theory 2007, Nice, France | null | null | null | cs.IT math.IT | null | We establish the optimal diversity-multiplexing (DM) tradeoff of coherent
time, frequency and time-frequency selective-fading MIMO channels and provide a
code design criterion for DM-tradeoff optimality. Our results are based on the
analysis of the "Jensen channel" associated to a given selective-fading MIMO
channel. While the original problem seems analytically intractable due to the
mutual information being a sum of correlated random variables, the Jensen
channel is equivalent to the original channel in the sense of the DM-tradeoff
and lends itself nicely to analytical treatment. Finally, as a consequence of
our results, we find that the classical rank criterion for space-time code
design (in selective-fading MIMO channels) ensures optimality in the sense of
the DM-tradeoff.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 16:09:06 GMT"
}
] | 2007-07-13T00:00:00 | [
[
"Coronel",
"Pedro",
""
],
[
"Bölcskei",
"Helmut",
""
]
] |
0704.3403 | Chun Hay Kom | J. P. Conlon, C. H. Kom, K. Suruliz, B. C. Allanach, F. Quevedo | Sparticle Spectra and LHC Signatures for Large Volume String
Compactifications | 42 pages, 21 figures. Added references and discussion for section 3.
Slight changes in the text | JHEP 0708:061,2007 | 10.1088/1126-6708/2007/08/061 | DAMTP-2007-33 | hep-ph hep-th | null | We study the supersymmetric particle spectra and LHC collider observables for
the large-volume string models with a fundamental scale of 10^{11} GeV that
arise in moduli-fixed string compactifications with branes and fluxes. The
presence of magnetic fluxes on the brane world volume, required for chirality,
perturb the soft terms away from those previously computed in the dilute-flux
limit. We use the difference in high-scale gauge couplings to estimate the
magnitude of this perturbation and study the potential effects of the magnetic
fluxes by generating many random spectra with the soft terms perturbed around
the dilute flux limit. Even with a 40% variation in the high-scale soft terms
the low-energy spectra take a clear and predictive form. The resulting spectra
are broadly similar to those arising on the SPS1a slope, but more degenerate.
In their minimal version the models predict the ratios of gaugino masses to be
M_1 : M_2 : M_3=(1.5 - 2) : 2 : 6, different to both mSUGRA and mirage
mediation. Among the scalars, the squarks tend to be lighter and the sleptons
heavier than for comparable mSUGRA models. We generate 10 fb^{-1} of sample LHC
data for the random spectra in order to study the range of collider
phenomenology that can occur. We perform a detailed mass reconstruction on one
example large-volume string model spectrum. 100 fb^{-1} of integrated
luminosity is sufficient to discriminate the model from mSUGRA and aspects of
the sparticle spectrum can be accurately reconstructed.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 16:25:10 GMT"
},
{
"version": "v2",
"created": "Tue, 15 May 2007 21:38:12 GMT"
},
{
"version": "v3",
"created": "Sat, 16 Jun 2007 02:29:09 GMT"
},
{
"version": "v4",
"created": "Sat, 4 Aug 2007 10:12:50 GMT"
}
] | 2009-01-06T00:00:00 | [
[
"Conlon",
"J. P.",
""
],
[
"Kom",
"C. H.",
""
],
[
"Suruliz",
"K.",
""
],
[
"Allanach",
"B. C.",
""
],
[
"Quevedo",
"F.",
""
]
] |
0704.3404 | Agissilaos Athanassoulis | Agissilaos G. Athanassoulis | Smoothed Wigner transforms in the numerical simulation of semiclassical
(high-frequency) wave propagation | null | Dynamics of Continuous, Discrete and Impulsive Systems Series A,
S2, 2007 | null | null | math.AP math.NA | null | The numerical simulation of wave propagation in semiclassical
(high-frequency) problems is well known to pose a formidable challenge. In this
work, a new phase-space approach for the numerical simulation of semiclassical
wave propagation, making use of the smoothed Wigner Transform (SWT), is
proposed. There are numerous works which use the Wigner Transform (WT) in the
study of a variety of wave propagation problems including high-frequency limits
for linear, nonlinear and/or random waves. The WT however is well known to
present significant difficulties in the formulation of numerical schemes.
Working with concrete examples for the semiclassical linear Schrodinger
equation it is seen that the SWT approach is indeed significantly faster (in a
well-defined sense) to work with than the WT and than full numerical solutions
of the original equation in the semiclassical regime. Comparisons with exact
and numerical solutions are used to keep track of numerical errors.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 16:21:28 GMT"
}
] | 2008-10-30T00:00:00 | [
[
"Athanassoulis",
"Agissilaos G.",
""
]
] |
0704.3405 | Shuguang Cui | Shuguang Cui and Jinjun Xiao and Andrea Goldsmith and Zhi-Quan Luo and
H. Vincent Poor | Estimation Diversity and Energy Efficiency in Distributed Sensing | To appear at IEEE Transactions on Signal Processing | null | 10.1109/TSP.2007.896019 | null | cs.IT math.IT | null | Distributed estimation based on measurements from multiple wireless sensors
is investigated. It is assumed that a group of sensors observe the same
quantity in independent additive observation noises with possibly different
variances. The observations are transmitted using amplify-and-forward (analog)
transmissions over non-ideal fading wireless channels from the sensors to a
fusion center, where they are combined to generate an estimate of the observed
quantity. Assuming that the Best Linear Unbiased Estimator (BLUE) is used by
the fusion center, the equal-power transmission strategy is first discussed,
where the system performance is analyzed by introducing the concept of
estimation outage and estimation diversity, and it is shown that there is an
achievable diversity gain on the order of the number of sensors. The optimal
power allocation strategies are then considered for two cases: minimum
distortion under power constraints; and minimum power under distortion
constraints. In the first case, it is shown that by turning off bad sensors,
i.e., sensors with bad channels and bad observation quality, adaptive power
gain can be achieved without sacrificing diversity gain. Here, the adaptive
power gain is similar to the array gain achieved in Multiple-Input
Single-Output (MISO) multi-antenna systems when channel conditions are known to
the transmitter. In the second case, the sum power is minimized under
zero-outage estimation distortion constraint, and some related energy
efficiency issues in sensor networks are discussed.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 16:30:31 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Cui",
"Shuguang",
""
],
[
"Xiao",
"Jinjun",
""
],
[
"Goldsmith",
"Andrea",
""
],
[
"Luo",
"Zhi-Quan",
""
],
[
"Poor",
"H. Vincent",
""
]
] |
0704.3406 | Martin Weigt | Hamed Mahmoudi, Andrea Pagnani, Martin Weigt, Riccardo Zecchina | Propagation of external regulation and asynchronous dynamics in random
Boolean networks | 19 pages, 14 figures, to appear in Chaos | Chaos 17, 026109 (2007) | 10.1063/1.2742931 | null | cond-mat.stat-mech cond-mat.dis-nn q-bio.MN | null | Boolean Networks and their dynamics are of great interest as abstract
modeling schemes in various disciplines, ranging from biology to computer
science. Whereas parallel update schemes have been studied extensively in past
years, the level of understanding of asynchronous updates schemes is still very
poor. In this paper we study the propagation of external information given by
regulatory input variables into a random Boolean network. We compute both
analytically and numerically the time evolution and the asymptotic behavior of
this propagation of external regulation (PER). In particular, this allows us to
identify variables which are completely determined by this external
information. All those variables in the network which are not directly fixed by
PER form a core which contains in particular all non-trivial feedback loops. We
design a message-passing approach allowing to characterize the statistical
properties of these cores in dependence of the Boolean network and the external
condition. At the end we establish a link between PER dynamics and the full
random asynchronous dynamics of a Boolean network.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 16:35:14 GMT"
}
] | 2007-07-19T00:00:00 | [
[
"Mahmoudi",
"Hamed",
""
],
[
"Pagnani",
"Andrea",
""
],
[
"Weigt",
"Martin",
""
],
[
"Zecchina",
"Riccardo",
""
]
] |
0704.3407 | Solange Odile Saliu | C. Bizdadea, E. M. Cioroianu, I. Negru, S. O. Saliu, S. C. Sararu | On the generalized Freedman-Townsend model | LaTeX, 62 pages | JHEP0610:004,2006 | 10.1088/1126-6708/2006/10/004 | null | hep-th | null | Consistent interactions that can be added to a free, Abelian gauge theory
comprising a finite collection of BF models and a finite set of two-form gauge
fields (with the Lagrangian action written in first-order form as a sum of
Abelian Freedman-Townsend models) are constructed from the deformation of the
solution to the master equation based on specific cohomological techniques.
Under the hypotheses of smoothness in the coupling constant, locality, Lorentz
covariance, and Poincare invariance of the interactions, supplemented with the
requirement on the preservation of the number of derivatives on each field with
respect to the free theory, we obtain that the deformation procedure modifies
the Lagrangian action, the gauge transformations as well as the accompanying
algebra. The interacting Lagrangian action contains a generalized version of
non-Abelian Freedman-Townsend model. The consistency of interactions to all
orders in the coupling constant unfolds certain equations, which are shown to
have solutions.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 16:38:09 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Bizdadea",
"C.",
""
],
[
"Cioroianu",
"E. M.",
""
],
[
"Negru",
"I.",
""
],
[
"Saliu",
"S. O.",
""
],
[
"Sararu",
"S. C.",
""
]
] |
0704.3408 | Sinan Gezici Dr | Sinan Gezici, Andreas F. Molisch, H. Vincent Poor, and Hisashi
Kobayashi | The Trade-off between Processing Gains of an Impulse Radio UWB System in
the Presence of Timing Jitter | To appear in the IEEE Transactions on Communications | null | null | null | cs.IT math.IT | null | In time hopping impulse radio, $N_f$ pulses of duration $T_c$ are transmitted
for each information symbol. This gives rise to two types of processing gain:
(i) pulse combining gain, which is a factor $N_f$, and (ii) pulse spreading
gain, which is $N_c=T_f/T_c$, where $T_f$ is the mean interval between two
subsequent pulses. This paper investigates the trade-off between these two
types of processing gain in the presence of timing jitter. First, an additive
white Gaussian noise (AWGN) channel is considered and approximate closed form
expressions for bit error probability are derived for impulse radio systems
with and without pulse-based polarity randomization. Both symbol-synchronous
and chip-synchronous scenarios are considered. The effects of multiple-access
interference and timing jitter on the selection of optimal system parameters
are explained through theoretical analysis. Finally, a multipath scenario is
considered and the trade-off between processing gains of a synchronous impulse
radio system with pulse-based polarity randomization is analyzed. The effects
of the timing jitter, multiple-access interference and inter-frame interference
are investigated. Simulation studies support the theoretical results.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 16:47:35 GMT"
}
] | 2007-07-13T00:00:00 | [
[
"Gezici",
"Sinan",
""
],
[
"Molisch",
"Andreas F.",
""
],
[
"Poor",
"H. Vincent",
""
],
[
"Kobayashi",
"Hisashi",
""
]
] |
0704.3409 | Cyrille Marquet | C. Marquet and C. Royon | Azimuthal decorrelation of Mueller-Navelet jets at the Tevatron and the
LHC | 11 pages, 7 figures, energy conservation effects added | Phys.Rev.D79:034028,2009 | 10.1103/PhysRevD.79.034028 | null | hep-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the production of Mueller-Navelet jets at hadron colliders in the
Balitsky-Fadin-Kuraev-Lipatov (BFKL) framework. We show that a measurement of
the relative azimuthal angle \Delta\Phi between the jets can provide a good
testing ground for corrections due to next-leading logarithms (NLL). Besides
the well-known azimuthal decorrelation with increasing rapidity interval
\Delta\eta between the jets, we propose to also measure this effect as a
function of R=k_2/k_1, the ratio between the jets transverse momenta. Using
renormalisation-group improved NLL kernel, we obtain predictions for
d\sigma/d\Delta\eta dR d\Delta\Phi. We analyse NLL-scheme and
renormalisation-scale uncertainties, and energy-momentum conservation effects,
in order to motivate a measurement at the Tevatron and the LHC.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 16:59:26 GMT"
},
{
"version": "v2",
"created": "Wed, 5 Nov 2008 22:36:03 GMT"
}
] | 2009-03-12T00:00:00 | [
[
"Marquet",
"C.",
""
],
[
"Royon",
"C.",
""
]
] |
0704.3410 | C. Douglas Haessig | C. Douglas Haessig | On the $p$-adic meromorphy of the function field height zeta function | 5 pages. Comments welcome | null | null | null | math.NT math.AG | null | In this brief note, we will investigate the number of points of bounded
(twisted) height in a projective variety defined over a function field, where
the function field comes from a projective variety of dimension greater than or
equal to 2. A first step in this investigation is to understand the $p$-adic
analytic properties of the height zeta function. In particular, we will show
that for a large class of projective varieties this function is $p$-adic
meromorphic.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 17:03:37 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Haessig",
"C. Douglas",
""
]
] |
0704.3411 | Alexander Felshtyn | Collin Bleak, Alexander Fel'shtyn and Daciberg L. Gon\c{c}alves | Twisted conjugacy classes in R. Thompson's group F | 10 pages | null | null | null | math.GR math.AT | null | In this short article, we prove that any automorphism of the R. Thompson's
group $F$ has infinitely many twisted conjugacy classes. The result follows
from the work of Matthew Brin, together with a standard facts on R. Thompson's
group $F$, and elementary properties of the Reidemeister numbers.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 17:06:27 GMT"
},
{
"version": "v2",
"created": "Sat, 5 May 2007 18:53:23 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Bleak",
"Collin",
""
],
[
"Fel'shtyn",
"Alexander",
""
],
[
"Gonçalves",
"Daciberg L.",
""
]
] |
0704.3412 | Vladimir Berezovsky | V.V.Berezovsky, L.I.Men'shikov, S.Oberg and C.D.Latham | The effect of dipole-dipole interactions between atoms in an active
medium | 8 pages, 7 figures | null | 10.1364/JOSAB.25.000458 | null | cond-mat.str-el cond-mat.other | null | Based on the results of numerical modeling, it is shown that dipole-dipole
interactions among atoms in the active medium influences strongly the character
of the associated superradiation. The main effect is to make the nuclear
subsystem behave chaotically. Its strength increases with the atom density, and
leads to the suppression of distant collective correlations and superradiation.
Near correlations between the atoms are established, causing a confinement
effect: a shielding of radiation in the active medium.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 17:15:25 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Berezovsky",
"V. V.",
""
],
[
"Men'shikov",
"L. I.",
""
],
[
"Oberg",
"S.",
""
],
[
"Latham",
"C. D.",
""
]
] |
0704.3413 | Pietro Antonio Grassi | Pietro Fr\'e, Pietro Antonio Grassi | Constrained Supermanifolds for AdS M-Theory Backgrounds | LaTex, 47 pages, no figures | JHEP0801:036,2008 | 10.1088/1126-6708/2008/01/036 | DISTA-2007 | hep-th | null | A long standing problem is the supergauge completion of AdS_4 x (G/H)_7 or
AdS_5 x (G/H)_5 backgrounds which preserve less then maximal supersymmetry. In
parallel with the supersolvable realization of the AdS_4 x S^7 background based
on Kappa-symmetry, we develop a technique which amounts to solving the
above-mentioned problem in a way useful for pure spinor quantization for
supermembranes and superstrings. Instead of gauge fixing some of the superspace
coordinates to zero, we impose an additional constraint on them reproducing the
simplifications of the supersolvable representations. The constraints are
quadratic, homogeneous, Sp(4,R)-covariant, and consistent from the quantum
point of view in the pure spinor approach. Here we provide the geometrical
solution which, in a subsequent work, will be applied to the membrane and the
superstring sigma models.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 17:15:58 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Fré",
"Pietro",
""
],
[
"Grassi",
"Pietro Antonio",
""
]
] |
0704.3414 | Burin Gumjudpai | Daris Samart and Burin Gumjudpai (TPTP Naresuan U.) | Phantom field dynamics in loop quantum cosmology | 8 pages, 6 figures, Revtex 4, Figures and References added. Version
accepted by Physical Review D15 | Phys.Rev.D76:043514,2007 | 10.1103/PhysRevD.76.043514 | null | gr-qc astro-ph hep-ph | null | We consider a dynamical system of phantom scalar field under exponential
potential in background of loop quantum cosmology. In our analysis, there is
neither stable node nor repeller unstable node but only two saddle points,
hence no Big Rip singularity. Physical solutions always possess potential
energy greater than magnitude of the negative kinetic energy. We found that the
universe bounces after accelerating even in the domination of the phantom
field. After bouncing, the universe finally enters oscillatory regime.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 17:25:35 GMT"
},
{
"version": "v2",
"created": "Mon, 7 May 2007 08:51:53 GMT"
},
{
"version": "v3",
"created": "Sat, 7 Jul 2007 05:36:51 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Samart",
"Daris",
"",
"TPTP Naresuan U."
],
[
"Gumjudpai",
"Burin",
"",
"TPTP Naresuan U."
]
] |
0704.3415 | Aurelian Isar | A. Isar | Quantum decoherence in the theory of open systems | 6 pages; talk at the 3rd International Workshop "Quantum Physics and
Communication" (QPC 2005), Dubna, Russia, 2005 | Phys. Part. Nuclei Lett. 4, 133 (2007) | 10.1134/S1547477107020070 | null | quant-ph | null | In the framework of the Lindblad theory for open quantum systems, we
determine the degree of quantum decoherence of a harmonic oscillator
interacting with a thermal bath. It is found that the system manifests a
quantum decoherence which is more and more significant in time. We calculate
also the decoherence time scale and analyze the transition from quantum to
classical behaviour of the considered system.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 19:12:01 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Isar",
"A.",
""
]
] |
0704.3416 | Roc\'io Blanco | Rocio Blanco | Complexity of Villamayor's algorithm in the non exceptional monomial
case | 17 pages, to appear in International Journal of Mathematics.
Corrected format | null | null | null | math.AG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study monomial ideals, always locally given by a monomial, like a
reasonable first step to estimate in general the number of monoidal
transformations of Villamayor's algorithm of resolution of singularities. The
resolution of a monomial ideal $<X_1^{a_1}\cdot ... \cdot X_n^{a_n}>$ is
interesting due to its identification with the particular toric problem $<Z^c-
X_1^{a_1}\cdot ... \cdot X_n^{a_n}>$.
In the special case, when all the exponents $a_i$ are greater than or equal
to the critical value $c$, we construct the largest branch of the resolution
tree which provides an upper bound involving partial sums of Catalan numbers.
This case will be called ``minimal codimensional case''. Partial sums of
Catalan numbers (starting $1,2,5,...$) are $1,3,8,22,...$ These partial sums
are well known in Combinatorics and count the number of paths starting from the
root in all ordered trees with $n+1$ edges. Catalan numbers appear in many
combinatorial problems, counting the number of ways to insert $n$ pairs of
parenthesis in a word of $n+1$ letters, plane trees with $n+1$ vertices, $...
$, etc.
The non minimal case, when there exists some exponent $a_{i_0}$ smaller than
$c$, will be called ``case of higher codimension''. In this case, still
unresolved, we give an example to state the foremost troubles.
Computation of examples has been helpful in both cases to study the behaviour
of the resolution invariant. Computations have been made in Singular (see
\cite{sing}) using the \emph{desing} package by G. Bodn\'ar and J. Schicho, see
\cite{lib}.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 17:44:10 GMT"
},
{
"version": "v2",
"created": "Wed, 4 Jul 2007 15:56:05 GMT"
},
{
"version": "v3",
"created": "Fri, 23 May 2008 10:54:20 GMT"
},
{
"version": "v4",
"created": "Thu, 22 Jan 2009 12:55:06 GMT"
}
] | 2009-01-22T00:00:00 | [
[
"Blanco",
"Rocio",
""
]
] |
0704.3417 | Daniel Juteau | Daniel Juteau | Cohomology of the minimal nilpotent orbit | 29 pages, v2 : Leray-Serre spectral sequence replaced by Gysin
sequence only, corrected typos | Transformation Groups 13 (2), 355-387 (2008) | 10.1007/s00031-008-9009-x | null | math.RT | null | We compute the integral cohomology of the minimal non-trivial nilpotent orbit
in a complex simple (or quasi-simple) Lie algebra. We find by a uniform
approach that the middle cohomology group is isomorphic to the fundamental
group of the sub-root system generated by the long simple roots. The modulo
$\ell$ reduction of the Springer correspondent representation involves the sign
representation exactly when $\ell$ divides the order of this cohomology group.
The primes dividing the torsion of the rest of the cohomology are bad primes.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 17:56:10 GMT"
},
{
"version": "v2",
"created": "Wed, 13 Jun 2007 15:09:41 GMT"
}
] | 2013-09-24T00:00:00 | [
[
"Juteau",
"Daniel",
""
]
] |
0704.3418 | Shannon Patel | Shannon G. Patel (1), Steven S. Vogt (1), Geoffrey W. Marcy (2), John
A. Johnson (2), Debra A. Fischer (3), Jason T. Wright (2), R. Paul Butler (4)
((1) UCSC, (2) Berkeley, (3) SFSU, (4) DTM) | Fourteen New Companions from the Keck & Lick Radial Velocity Survey
Including Five Brown Dwarf Candidates | 29 pages, 14 figures, accepted to ApJ | Astrophys.J.665:744-753,2007 | 10.1086/519066 | null | astro-ph | null | We present radial velocities for 14 stars on the California & Carnegie Planet
Search target list that reveal new companions. One star, HD 167665, was fit
with a definitive Keplerian orbit leading to a minimum mass for the companion
of 50.3 Mjup at a separation from its host of ~5.5 AU. Incomplete or limited
phase coverage for the remaining 13 stars prevents us from assigning to them
unique orbital parameters. Instead, we fit their radial velocities with
Keplerian orbits across a grid of fixed values for Msini and period, P, and use
the resulting reduced chi-square surface to place constraints on Msini, P, and
semimajor axis, a. This technique allowed us to restrict Msini below the brown
dwarf -- stellar mass boundary for an additional 4 companions (HD 150554, HD
8765, HD 72780, HD 74014). If the combined 5 companions are confirmed as brown
dwarfs, these results would comprise the first major catch of such objects from
our survey beyond ~3 AU.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 18:45:05 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Patel",
"Shannon G.",
"",
"UCSC"
],
[
"Vogt",
"Steven S.",
"",
"UCSC"
],
[
"Marcy",
"Geoffrey W.",
"",
"Berkeley"
],
[
"Johnson",
"John A.",
"",
"Berkeley"
],
[
"Fischer",
"Debra A.",
"",
"SFSU"
],
[
"Wright",
"Jason T.",
"",
"Berkeley"
],
[
"Butler",
"R. Paul",
"",
"DTM"
]
] |
0704.3419 | Bengt Eliasson | Bengt Eliasson, Bo Thid\'e | Zakharov simulation study of spectral features of on-demand Langmuir
turbulence in an inhomogeneous plasma | 7 pages, 8 figures | null | 10.1029/2007JA012491 | null | physics.space-ph | null | We have performed a simulation study of Langmuir turbulence in the Earth's
ionosphere by means of a Zakharov model with parameters relevant for the F
layer. The model includes dissipative terms to model collisions and Landau
damping of the electrons and ions, and a linear density profile, which models
the ionospheric plasma inhomogeneity whose length scale is of the order 10--100
km. The injection of energy into the system is modeled by a constant source
term in the Zakharov equation. Langmuir turbulence is excited ``on-demand'' in
controlled ionospheric modification experiments where the energy is provided by
an HF radio beam injected into the overhead ionospheric plasma. The ensuing
turbulence can be studied with radars and in the form of secondary radiation
recorded by ground-based receivers. We have analyzed spectral signatures of the
turbulence for different sets of parameters and different altitudes relative to
the turning point of the linear Langmuir mode where the Langmuir frequency
equals the local plasma frequency. By a parametric analysis, we have derived a
simple scaling law, which links the spectral width of the turbulent frequency
spectrum to the physical parameters in the ionosphere. The scaling law provides
a quantitative relation between the physical parameters (temperatures, electron
number density, ionospheric length scale, etc.) and the observed frequency
spectrum. This law may be useful for interpreting experimental results.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 18:25:58 GMT"
},
{
"version": "v2",
"created": "Sat, 11 Aug 2007 05:18:02 GMT"
}
] | 2015-05-13T00:00:00 | [
[
"Eliasson",
"Bengt",
""
],
[
"Thidé",
"Bo",
""
]
] |
0704.3420 | Peter Morgan | Peter Morgan | Lie fields revisited | 13 pages; to appear in J.Math.Phys | J. Math. Phys. 48, 122302 (2007) | 10.1063/1.2825148 | null | quant-ph hep-th math-ph math.MP | null | A class of interacting classical random fields is constructed using deformed
*-algebras of creation and annihilation operators. The fields constructed are
classical random field versions of "Lie fields". A vacuum vector is used to
construct linear forms over the algebras, which are conjectured to be states
over the algebras. Assuming this conjecture is true, the fields constructed are
"quantum random fields" in the sense that they have Poincare invariant vacua
with a fluctuation scale determined by Planck's constant. A nonlocal particle
interpretation of the formalism is shown to be the same as a particle
interpretation of a quantum field theory.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 18:13:06 GMT"
},
{
"version": "v2",
"created": "Tue, 27 Nov 2007 02:24:10 GMT"
}
] | 2008-10-15T00:00:00 | [
[
"Morgan",
"Peter",
""
]
] |
0704.3421 | Lars Winther Christensen | Lars Winther Christensen, Greg Piepmeyer, Janet Striuli, and Ryo
Takahashi | Finite Gorenstein representation type implies simple singularity | Final version, to appear in Adv. Math. 14 pp | null | null | null | math.AC math.RT | null | Let R be a commutative noetherian local ring and consider the set of
isomorphism classes of indecomposable totally reflexive R-modules. We prove
that if this set is finite, then either it has exactly one element, represented
by the rank 1 free module, or R is Gorenstein and an isolated singularity (if R
is complete, then it is even a simple hypersurface singularity). The crux of
our proof is to argue that if the residue field has a totally reflexive cover,
then R is Gorenstein or every totally reflexive R-module is free.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 18:26:23 GMT"
},
{
"version": "v2",
"created": "Fri, 22 Feb 2008 17:45:35 GMT"
}
] | 2008-02-22T00:00:00 | [
[
"Christensen",
"Lars Winther",
""
],
[
"Piepmeyer",
"Greg",
""
],
[
"Striuli",
"Janet",
""
],
[
"Takahashi",
"Ryo",
""
]
] |
0704.3422 | Jeff Viaclovsky | Simon Salamon and Jeff Viaclovsky | Orthogonal complex structures on domains in R^4 | 42 pages. Version 2 contains several improvements and simplifications
throughout. Material from the first version on more general branched
coverings has been removed in order to make the article more focused, and
will appear elsewhere | Final version: Math. Annalen 343, no. 4, 2009, 853-899 | null | null | math.DG math.AG math.AP | null | An orthogonal complex structure on a domain in R^4 is a complex structure
which is integrable and is compatible with the Euclidean metric. This gives
rise to a first order system of partial differential equations which is
conformally invariant. We prove two Liouville-type uniqueness theorems for
solutions of this system, and use these to give an alternative proof of the
classification of compact locally conformally flat Hermitian surfaces first
proved by Pontecorvo. We also give a classification of non-degenerate quadrics
in CP^3 under the action of the conformal group. Using this classification, we
show that generic quadrics give rise to orthogonal complex structures defined
on the complement of unknotted solid tori which are smoothly embedded in R^4.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 18:44:41 GMT"
},
{
"version": "v2",
"created": "Tue, 8 Apr 2008 21:08:08 GMT"
}
] | 2009-08-26T00:00:00 | [
[
"Salamon",
"Simon",
""
],
[
"Viaclovsky",
"Jeff",
""
]
] |
0704.3423 | Cristiano Ciuti | Arnaud Verger (LPA), Iacopo Carusotto (BEC-CNR-INFM), Cristiano Ciuti
(MPQ) | Quantum Monte Carlo study of ring-shaped polariton parametric
luminescence in a semiconductor microcavity | null | Physical Review B 76 (2007) 115324 | 10.1103/PhysRevB.76.115324 | null | cond-mat.other | null | We present a quantum Monte Carlo study of the quantum correlations in the
parametric luminescence from semiconductor microcavities in the strong
exciton-photon coupling regime. As already demonstrated in recent experiments,
a ring-shaped emission is obtained by applying two identical pump beams with
opposite in-plane wavevectors, providing symmetrical signal and idler beams
with opposite in-plane wavevectors on the ring. We study the squeezing of the
signal-idler difference noise across the parametric instability threshold,
accounting for the radiative and non-radiative losses, multiple scattering and
static disorder. We compare the results of the complete multimode Monte Carlo
simulations with a simplified linearized quantum Langevin analytical model.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 18:54:39 GMT"
},
{
"version": "v2",
"created": "Thu, 19 Jul 2007 14:43:00 GMT"
}
] | 2015-05-13T00:00:00 | [
[
"Verger",
"Arnaud",
"",
"LPA"
],
[
"Carusotto",
"Iacopo",
"",
"BEC-CNR-INFM"
],
[
"Ciuti",
"Cristiano",
"",
"MPQ"
]
] |
0704.3424 | Jeremy Carroll | Jeremy J. Carroll | A New Proof of Pappus's Theorem | 47 pages, 27 figures (typo corrected) | null | null | null | math.CO math.MG | null | Any stretching of Ringel's non-Pappus pseudoline arrangement when projected
into the Euclidean plane, implicitly contains a particular arrangement of nine
triangles. This arrangement has a complex constraint involving the sines of its
angles. These constraints cannot be satisfied by any projection of the initial
arrangement. This is sufficient to prove Pappus's theorem. The derivation of
the constraint is via systems of inequalities arising from the polar
coordinates of the lines. These systems are linear in r for any given theta,
and their solubility can be analysed in terms of the signs of determinants. The
evaluation of the determinants is via a normal form for sums of products of
sines, giving a powerful system of trigonometric identities. The particular
result is generalized to arrangements derived from three edge connected totally
cyclic directed graphs, conjectured to be sufficient for a complete analysis of
angle constraining arrangements of lines, and thus a full response to Ringel's
slope conjecture. These methods are generally applicable to the realizability
problem for rank 3 oriented matroids.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 19:06:58 GMT"
},
{
"version": "v2",
"created": "Wed, 25 Apr 2007 23:16:31 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Carroll",
"Jeremy J.",
""
]
] |
0704.3425 | Mustapha Bentaiba | S.-A. Yahiaoui, H. Zerguini, M. Bentaiba | New Solvable Shape-Invariant Potentials for Position-Dependent Effective
Mass | 20 pages, 0 figure | null | null | null | math-ph math.MP | null | Four new exactly solvable, real and shape-invariant potentials associated
with a position-dependent effective mass are generated within the concept of
shape-invariant potentials using a specific ansatz for superpotential. The
accompanying energy spectra of the bound-state and the ground-state
wavefunction are obtained algebraically as a function of free parameters and
the results are compared with those of others works in the litterature.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 19:07:02 GMT"
}
] | 2007-05-25T00:00:00 | [
[
"Yahiaoui",
"S. -A.",
""
],
[
"Zerguini",
"H.",
""
],
[
"Bentaiba",
"M.",
""
]
] |
0704.3426 | Neil Barnaby | N. Barnaby and J. M. Cline | Large Nongaussianity from Nonlocal Inflation | 27 pages, no figures. Added references and some clarifying remarks | JCAP 0707:017,2007 | 10.1088/1475-7516/2007/07/017 | null | hep-th astro-ph hep-ph | null | We study the possibility of obtaining large nongaussian signatures in the
Cosmic Microwave Background in a general class of single-field nonlocal
hill-top inflation models. We estimate the nonlinearity parameter f_{NL} which
characterizes nongaussianity in such models and show that large nongaussianity
is possible. For the recently proposed p-adic inflation model we find that
f_{NL} ~ 120 when the string coupling is order unity. We show that large
nongaussianity is also possible in a toy model with an action similar to those
which arise in string field theory.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 19:11:56 GMT"
},
{
"version": "v2",
"created": "Fri, 14 Sep 2007 14:03:46 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Barnaby",
"N.",
""
],
[
"Cline",
"J. M.",
""
]
] |
0704.3427 | Yusuke Sasano | Yusuke Sasano | Five-parameter family of partial differential systems in two variables | 9 pages, 2 figures | null | null | null | math.AG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We find a five-parameter family of partial differential systems in two
variables with two polynomial Hamiltonians. We give its symmetry and holomorphy
conditions. These symmetries, holomorphy conditions and invariant divisors are
new.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 19:20:15 GMT"
},
{
"version": "v2",
"created": "Wed, 18 Nov 2009 10:55:45 GMT"
}
] | 2009-11-18T00:00:00 | [
[
"Sasano",
"Yusuke",
""
]
] |
0704.3428 | Grygiel Krzysztof | I. Sliwa, P. Szlachetka, K. Grygiel | Generation of strongly chaotic beats | 10 pages, 4 figures, accepted for publication in Int.J.Bif.Chaos | Int. J. Bif. Chaos vol.18, 835 (2008) | 10.1142/S0218127408020689 | null | nlin.CD | null | The letter proposes a procedure for generation of strongly chaotic beats that
have been hardly obtainable hitherto. The beats are generated in a nonlinear
optical system governing second-harmonic generation of light. The proposition
is based on the concept of an optical coupler but can be easily adopted to
other nonlinear systems and Chua's circuits.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 19:20:18 GMT"
}
] | 2015-05-13T00:00:00 | [
[
"Sliwa",
"I.",
""
],
[
"Szlachetka",
"P.",
""
],
[
"Grygiel",
"K.",
""
]
] |
0704.3429 | Carlos Kozameh | Carlos Kozameh and Florencia Parisi | Light Propagation on Quantum Curved Spacetime and Back reaction effects | null | Class.Quant.Grav.24:4475-4490,2007 | 10.1088/0264-9381/24/17/013 | null | gr-qc | null | We study the electromagnetic field equations on an arbitrary quantum curved
background in the semiclassical approximation of Loop Quantum Gravity. The
effective interaction hamiltonian for the Maxwell and gravitational fields is
obtained and the corresponding field equations, which can be expressed as a
modified wave equation for the Maxwell potential, are derived. We use these
results to analyze electromagnetic wave propagation on a quantum
Robertson-Walker space time and show that Lorentz Invariance is not preserved.
The formalism developed can be applied to the case where back reaction effects
on the metric due to the electromagnetic field are taken into account, leading
to non covariant field equations.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 19:27:44 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Kozameh",
"Carlos",
""
],
[
"Parisi",
"Florencia",
""
]
] |
0704.3430 | Edward Eyler | E. E. Eyler, D. E. Chieda, Matthew C. Stowe, Michael J. Thorpe, T. R.
Schibli, and Jun Ye | Prospects for precision measurements of atomic helium using direct
frequency comb spectroscopy | Shortened slightly and reformatted for Eur. Phys. J. D | Eur. Phys. J. D 48, 43-55 (2008) | 10.1140/epjd/e2007-00289-y | null | physics.atom-ph | null | We analyze several possibilities for precisely measuring electronic
transitions in atomic helium by the direct use of phase-stabilized femtosecond
frequency combs. Because the comb is self-calibrating and can be shifted into
the ultraviolet spectral region via harmonic generation, it offers the prospect
of greatly improved accuracy for UV and far-UV transitions. To take advantage
of this accuracy an ultracold helium sample is needed. For measurements of the
triplet spectrum a magneto-optical trap (MOT) can be used to cool and trap
metastable 2^3S state atoms. We analyze schemes for measuring the two-photon
$2^3S \to 4^3S$ interval, and for resonant two-photon excitation to high
Rydberg states, $2^3S \to 3^3P \to n^3S,D$. We also analyze experiments on the
singlet-state spectrum. To accomplish this we propose schemes for producing and
trapping ultracold helium in the 1^1S or 2^1S state via intercombination
transitions. A particularly intriguing scenario is the possibility of measuring
the $1^1S \to 2^1S$ transition with extremely high accuracy by use of
two-photon excitation in a magic wavelength trap that operates identically for
both states. We predict a ``triple magic wavelength'' at 412 nm that could
facilitate numerous experiments on trapped helium atoms, because here the
polarizabilities of the 1^1S, 2^1S and 2^3S states are all similar, small, and
positive.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 19:28:34 GMT"
},
{
"version": "v2",
"created": "Fri, 27 Apr 2007 01:42:04 GMT"
},
{
"version": "v3",
"created": "Wed, 11 Jul 2007 20:26:38 GMT"
}
] | 2008-06-23T00:00:00 | [
[
"Eyler",
"E. E.",
""
],
[
"Chieda",
"D. E.",
""
],
[
"Stowe",
"Matthew C.",
""
],
[
"Thorpe",
"Michael J.",
""
],
[
"Schibli",
"T. R.",
""
],
[
"Ye",
"Jun",
""
]
] |
0704.3431 | Gary Mamon | Jean-Christophe Mauduit (1) and Gary A. Mamon (1,2) ((1) Institut
d'Astrophysique de Paris (2) GEPI, Observatoire de Paris) | Suppressed radio emission in supercluster galaxies: enhanced ram
pressure in merging clusters? | Version consolidated with Erratum A&A 499, 45 | A&A (2007) 475, 169-185 (2007); Erratum in A&A (2009) 499,45 | 10.1051/0004-6361:20077721 | null | astro-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The environmental influence on the 1.4 GHz continuum radio emission of
galaxies is analyzed in a 600 deg2 region of the local Universe containing the
Shapley Supercluster (SSC). Galaxies in the FLASH and 6dFGS redshift surveys
are cross-identified with NVSS radio sources, selected in a subsample doubly
complete in volume and luminosity. Environmental effects are studied through a
smoothed density field (normalized with random catalogs with the same survey
edges and redshift selection function) and the distance to the nearest cluster
(R/r200, where r200 is the virial radius, whose relation to the aperture
velocity dispersion is quantified). The fraction of high radio loudness
(R_K=L_radio/L_K) galaxies in the 10 Mpc Abell 3558 cluster complex at the core
of the SSC (SSC-CR) is half as large than elsewhere. In the SSC-CR, R_K is
anti-correlated with the density of the large-scale environment and correlated
with R/r200: central brightest cluster galaxies (BCGs) in the SSC-CR are 10x
less radio-loud than BCGs elsewhere, with signs of suppressed radio loudness in
the SSC-CR also present beyond the BCGs, out to at least 0.3 r200. This
correlation is nearly as strong as the tight correlation of L_K with R/r200
(K-luminosity segregation), inside the SSC-CR. The suppression of radio
loudness in SSC-CR BCGs can be attributed to cluster-cluster mergers that
destroy the cool core and thus the supply of gas to the central AGN. We
analytically demonstrate that the low radio loudness of non-BCG galaxies within
SSC-CR clusters cannot be explained by direct major galaxy mergers or rapid
galaxy flyby collisions, but by the loss of gas supply through the enhanced ram
pressure felt when these galaxies cross the shock front between the 2 merging
clusters and are later subjected to the stronger wind from the 2nd cluster.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 19:52:37 GMT"
},
{
"version": "v2",
"created": "Tue, 4 Sep 2007 14:38:06 GMT"
},
{
"version": "v3",
"created": "Mon, 29 Jun 2009 15:32:09 GMT"
}
] | 2012-02-21T00:00:00 | [
[
"Mauduit",
"Jean-Christophe",
""
],
[
"Mamon",
"Gary A.",
""
]
] |
0704.3432 | Karl Gerd Vollbrecht | K. G. H. Vollbrecht and J. I. Cirac | Quantum simulators, continuous-time automata, and translationally
invariant systems | partily rewritten and important references included | Phys. Rev. Lett. 100, 010501 (2008) | 10.1103/PhysRevLett.100.010501 | null | quant-ph | null | The general problem of finding the ground state energy of lattice
Hamiltonians is known to be very hard, even for a quantum computer. We show
here that this is the case even for translationally invariant systems. We also
show that a quantum computer can be built in a 1D chain with a fixed,
translationally invariant Hamitonian consisting of nearest--neighbor
interactions only. The result of the computation is obtained after a prescribed
time with high probability.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 19:49:51 GMT"
},
{
"version": "v2",
"created": "Wed, 2 May 2007 19:19:31 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Vollbrecht",
"K. G. H.",
""
],
[
"Cirac",
"J. I.",
""
]
] |
0704.3433 | Tshilidzi Marwala | Tshilidzi Marwala and Bodie Crossingham | Bayesian approach to rough set | 20 pages, 3 figures | null | null | null | cs.AI | null | This paper proposes an approach to training rough set models using Bayesian
framework trained using Markov Chain Monte Carlo (MCMC) method. The prior
probabilities are constructed from the prior knowledge that good rough set
models have fewer rules. Markov Chain Monte Carlo sampling is conducted through
sampling in the rough set granule space and Metropolis algorithm is used as an
acceptance criteria. The proposed method is tested to estimate the risk of HIV
given demographic data. The results obtained shows that the proposed approach
is able to achieve an average accuracy of 58% with the accuracy varying up to
66%. In addition the Bayesian rough set give the probabilities of the estimated
HIV status as well as the linguistic rules describing how the demographic
parameters drive the risk of HIV.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 19:50:59 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Marwala",
"Tshilidzi",
""
],
[
"Crossingham",
"Bodie",
""
]
] |
0704.3434 | Shuchin Aeron | Shuchin Aeron, Manqi Zhao and Venkatesh Saligrama | On sensing capacity of sensor networks for the class of linear
observation, fixed SNR models | 37 pages, single column | null | null | null | cs.IT math.IT | null | In this paper we address the problem of finding the sensing capacity of
sensor networks for a class of linear observation models and a fixed SNR
regime. Sensing capacity is defined as the maximum number of signal dimensions
reliably identified per sensor observation. In this context sparsity of the
phenomena is a key feature that determines sensing capacity. Precluding the SNR
of the environment the effect of sparsity on the number of measurements
required for accurate reconstruction of a sparse phenomena has been widely
dealt with under compressed sensing. Nevertheless the development there was
motivated from an algorithmic perspective. In this paper our aim is to derive
these bounds in an information theoretic set-up and thus provide algorithm
independent conditions for reliable reconstruction of sparse signals. In this
direction we first generalize the Fano's inequality and provide lower bounds to
the probability of error in reconstruction subject to an arbitrary distortion
criteria. Using these lower bounds to the probability of error, we derive upper
bounds to sensing capacity and show that for fixed SNR regime sensing capacity
goes down to zero as sparsity goes down to zero. This means that
disproportionately more sensors are required to monitor very sparse events. Our
next main contribution is that we show the effect of sensing diversity on
sensing capacity, an effect that has not been considered before. Sensing
diversity is related to the effective \emph{coverage} of a sensor with respect
to the field. In this direction we show the following results (a) Sensing
capacity goes down as sensing diversity per sensor goes down; (b) Random
sampling (coverage) of the field by sensors is better than contiguous location
sampling (coverage).
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 19:52:47 GMT"
},
{
"version": "v2",
"created": "Mon, 14 May 2007 19:08:44 GMT"
},
{
"version": "v3",
"created": "Mon, 4 Jun 2007 18:21:46 GMT"
}
] | 2007-07-13T00:00:00 | [
[
"Aeron",
"Shuchin",
""
],
[
"Zhao",
"Manqi",
""
],
[
"Saligrama",
"Venkatesh",
""
]
] |
0704.3435 | Graziano Vernizzi | Kevin L. Kohlstedt, Francisco Solis, Graziano Vernizzi, Monica Olvera
de la Cruz | Spontaneous chirality via long-range electrostatic forces | Revtex, 4 pages, 4 figures | null | 10.1103/PhysRevLett.99.030602 | null | cond-mat.soft cond-mat.stat-mech | null | We consider a model for periodic patterns of charges constrained over a
cylindrical surface. In particular we focus on patterns of chiral helices,
achiral rings or vertical lamellae, with the constraint of global
electroneutrality. We study the dependence of the patterns' size and pitch
angle on the radius of the cylinder and salt concentration. We obtain a phase
diagram by using numerical and analytic techniques. For pure Coulomb
interactions, we find a ring phase for small radii and a chiral helical phase
for large radii. At a critical salt concentration, the characteristic domain
size diverges, resulting in macroscopic phase segregation of the components and
restoring chiral symmetry. We discuss possible consequences and generalizations
of our model.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 19:52:55 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Kohlstedt",
"Kevin L.",
""
],
[
"Solis",
"Francisco",
""
],
[
"Vernizzi",
"Graziano",
""
],
[
"de la Cruz",
"Monica Olvera",
""
]
] |
0704.3436 | Mikhail Skvortsov | M. Houzet, M. A. Skvortsov | Mesoscopic fluctuations of the supercurrent in diffusive Josephson
junctions | 19 pages, 14 figures, 2 tables | Phys. Rev. B 77, 057002 (2008) | 10.1103/PhysRevB.77.024525 | null | cond-mat.mes-hall cond-mat.supr-con | null | We study mesoscopic fluctuations and weak localization correction to the
supercurrent in Josephson junctions with coherent diffusive electron dynamics
in the normal part. Two kinds of junctions are considered: a chaotic dot
coupled to superconductors by tunnel barriers and a diffusive junction with
transparent normal--superconducting interfaces. The amplitude of current
fluctuations and the weak localization correction to the average current are
calculated as functions of the ratio between the superconducting gap and the
electron dwell energy, temperature, and superconducting phase difference across
the junction. Technically, fluctuations on top of the spatially inhomogeneous
proximity effect in the normal region are described by the replicated version
of the \sigma-model. For the case of diffusive junctions with transparent
interfaces, the magnitude of mesoscopic fluctuations of the critical current
appears to be nearly 3 times larger than the prediction of the previous theory
which did not take the proximity effect into account.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 19:54:22 GMT"
}
] | 2008-03-10T00:00:00 | [
[
"Houzet",
"M.",
""
],
[
"Skvortsov",
"M. A.",
""
]
] |
0704.3437 | Andreas Koch | A.Koch, J.T. Kleyna, M.I. Wilkinson, E.K. Grebel, G.F. Gilmore, N.W.
Evans, R.F.G. Wyse, D.R. Harbeck | Stellar kinematics in the remote Leo II dwarf spheroidal galaxy --
Another brick in the wall | 17 pages, 10 figures, accepted for publication in the AJ | Astron.J.134:566-578,2007 | 10.1086/519380 | null | astro-ph | null | We present the projected velocity dispersion profile for the remote
(d=233kpc) Galactic dwarf spheroidal (dSph) galaxy Leo II, based on 171
discrete stellar radial velocities that were obtained from medium-resolution
spectroscopy using the FLAMES/GIRAFFE spectrograph at the European Southern
Observatory, Chile. The dispersion profile of those stars with good membership
probabilities is essentially flat with an amplitude of 6.6+-0.7 km/s over the
full radial extent of our data, which probe to the stellar boundary of this
galaxy. We find no evidence of any significant apparent rotation or velocity
asymmetry which suggests that tidal effects cannot be invoked to explain Leo
II's properties. From basic mass modeling, employing Jeans' equation, we derive
a mass out to the limiting radius of (2.7+-0.5) 10^7 Msun and a global mass to
light ratio of 27-45 in solar units, depending on the adopted total luminosity.
A cored halo profile and a mild amount of tangential velocity anisotropy is
found to account well for Leo II's observed kinematics, although we cannot
exclude the possibility of a cusped halo with radially varying velocity
anisotropy. All in all, this galaxy exhibits dark matter properties which
appear to be concordant with the other dSph satellites of the Milky Way, namely
a halo mass profile which is consistent with a central core and a total mass
which is similar to the common mass scale seen in other dSphs.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 19:58:28 GMT"
},
{
"version": "v2",
"created": "Wed, 25 Apr 2007 20:06:50 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Koch",
"A.",
""
],
[
"Kleyna",
"J. T.",
""
],
[
"Wilkinson",
"M. I.",
""
],
[
"Grebel",
"E. K.",
""
],
[
"Gilmore",
"G. F.",
""
],
[
"Evans",
"N. W.",
""
],
[
"Wyse",
"R. F. G.",
""
],
[
"Harbeck",
"D. R.",
""
]
] |
0704.3438 | Gabriele Ghisellini | G. Ghirlanda (1), Z. Bosnjak (2,1), G. Ghisellini (1), F. Tavecchio
(1), C. Firmani (1,3) ((1) INAF-Osservatorio Astronomico di Brera; (2)
Institut d'Astrophysique de Paris; (3) U.N.A.M. - Mexico) | Black-body components in Gamma-Ray Bursts spectra? | 14 pages, 13 figures, accepted for publication in MNRAS | Mon.Not.Roy.Astron.Soc.379:73-85,2007 | 10.1111/j.1365-2966.2007.11890.x | null | astro-ph | null | We study 7 Gamma Ray Bursts (GRBs), detected both by the BATSE instrument,
on-board the Compton Gamma Ray Observatory, and by the Wide Field Camera (WFC),
on-board BeppoSAX. These bursts have measured spectroscopic redshifts and are a
sizeable fraction of the bursts defining the correlation between the peak
energy E_peak (i.e. the peak of the vFv spectrum) and the total prompt
isotropic energy E_iso (the so called "Amati" relation). Recent theoretical
interpretations of this correlation assume that black-body emission dominates
the time resolved spectra of GRBs, even if, in the time integrated spectrum,
its presence may be hidden by the change of its temperature and by the dilution
of a possible non-thermal power law component. We perform a time resolved
spectral analysis, and show that the sum of a power-law and a black-body gives
acceptable fits to the time dependent spectra within the BATSE energy range,
but overpredicts the flux in the WFC X-ray range. Moreover, a fit with a cutoff
power-law plus a black-body is consistent with the WFC data, but the black-body
component contributes a negligible fraction of the total flux. On the contrary,
we find that fitting the spectra with a Band model or a simple cutoff power-law
model yields an X-ray flux and spectral slope which well matches the WFC
spectra.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 20:00:07 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Ghirlanda",
"G.",
""
],
[
"Bosnjak",
"Z.",
""
],
[
"Ghisellini",
"G.",
""
],
[
"Tavecchio",
"F.",
""
],
[
"Firmani",
"C.",
""
]
] |
0704.3439 | Dean Lee J | Dean Lee (North Carolina State University) | The symmetric heavy-light ansatz | 38 pages, 13 figures, revised manuscript includes results for 1D, 2D,
and 3D | Eur.Phys.J.A35:171-187,2008 | 10.1140/epja/i2008-10537-2 | null | cond-mat.supr-con nucl-th physics.atm-clus | null | The symmetric heavy-light ansatz is a method for finding the ground state of
any dilute unpolarized system of attractive two-component fermions.
Operationally it can be viewed as a generalization of the Kohn-Sham equations
in density functional theory applied to N-body density correlations. While the
original Hamiltonian has an exact Z_2 symmetry, the heavy-light ansatz breaks
this symmetry by skewing the mass ratio of the two components. In the limit
where one component is infinitely heavy, the many-body problem can be solved in
terms of single-particle orbitals. The original Z_2 symmetry is recovered by
enforcing Z_2 symmetry as a constraint on N-body density correlations for the
two components. For the 1D, 2D, and 3D attractive Hubbard models the method is
in very good agreement with exact Lanczos calculations for few-body systems at
arbitrary coupling. For the 3D attractive Hubbard model there is very good
agreement with lattice Monte Carlo results for many-body systems in the limit
of infinite scattering length.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 21:49:31 GMT"
},
{
"version": "v2",
"created": "Tue, 12 Feb 2008 19:01:25 GMT"
}
] | 2010-02-11T00:00:00 | [
[
"Lee",
"Dean",
"",
"North Carolina State University"
]
] |
0704.3440 | Subroto Mukerjee | Subroto Mukerjee, Cenke Xu, Joel E. Moore | Dynamical models and the phase ordering kinetics of the s=1 spinor
condensate | 14 pages with 9 figures | Phys. Rev. B 76, 104519 (2007) | 10.1103/PhysRevB.76.104519 | null | cond-mat.stat-mech cond-mat.soft | null | The $s=1$ spinor Bose condensate at zero temperature supports ferromagnetic
and polar phases that combine magnetic and superfluid ordering. We investigate
the formation of magnetic domains at finite temperature and magnetic field in
two dimensions in an optical trap. We study the general ground state phase
diagram of a spin-1 system and focus on a phase that has a magnetic Ising order
parameter and numerically determine the nature of the finite temperature
superfluid and magnetic phase transitions. We then study three different
dynamical models: model A, which has no conserved quantities, model F, which
has a conserved second sound mode and the Gross-Pitaevskii (GP) equation which
has a conserved density and magnetization. We find the dynamic critical
exponent to be the same for models A and F ($z=2$) but different for GP ($z
\approx 3$). Externally imposed magnetization conservation in models A and F
yields the value $z \approx 3$, which demonstrates that the only conserved
density relevant to domain formation is the magnetization density.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 22:02:28 GMT"
},
{
"version": "v2",
"created": "Fri, 27 Apr 2007 19:31:50 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Mukerjee",
"Subroto",
""
],
[
"Xu",
"Cenke",
""
],
[
"Moore",
"Joel E.",
""
]
] |
0704.3441 | Tereasa G. Brainerd | Ingolfur Agustsson and Tereasa G. Brainerd | Anisotropic Locations of Satellite Galaxies: Clues to the Orientations
of Galaxies within their Dark Matter Halos | 43 pages, 13 figures, ApJ in press | Astrophys.J.709:1321-1336,2010 | 10.1088/0004-637X/709/2/1321 | null | astro-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We investigate the locations of the satellites of relatively isolated host
galaxies in the Sloan Digital Sky Survey and the Millennium Run simulation.
Provided we use two distinct prescriptions to embed luminous galaxies within
the simulated dark matter halos (ellipticals share the shapes of their halos,
while disks have angular momenta that are aligned with the net angular momenta
of their halos), we find a fair agreement between observation and theory.
Averaged over scales r_p \le 500 kpc, the satellites of red, high-mass hosts
with low star formation rates are found preferentially near the major axes of
their hosts. In contrast, the satellites of blue, low-mass hosts with low star
formation rates show little to no anisotropy when averaged over the same scale.
The difference between the locations of the satellites of red and blue hosts
cannot be explained by the effects of interlopers in the data. Instead, it is
caused primarily by marked differences in the dependence of the mean satellite
location, <\phi>, on the projected distance at which the satellites are found.
We also find that the locations of red, high-mass satellites with low star
formation rates show considerably more anisotropy than do the locations of
blue, low--mass satellites with high star formation rates. There are two
contributors to this result. First, the blue satellites have only recently
arrived within their hosts' halos, while the red satellites arrived in the far
distant past. Second, the sample of blue satellites is heavily contaminated by
interlopers, which suppresses the measured anisotropy compared to the intrinsic
anisotropy.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 20:08:28 GMT"
},
{
"version": "v2",
"created": "Tue, 27 Oct 2009 19:33:50 GMT"
},
{
"version": "v3",
"created": "Thu, 3 Dec 2009 17:04:39 GMT"
}
] | 2010-01-21T00:00:00 | [
[
"Agustsson",
"Ingolfur",
""
],
[
"Brainerd",
"Tereasa G.",
""
]
] |
0704.3442 | Oleg Lunin | Oleg Lunin | 1/2-BPS states in M theory and defects in the dual CFTs | 82 pages, 12 figures, added refs | JHEP0710:014,2007 | 10.1088/1126-6708/2007/10/014 | EFI-07-12 | hep-th | null | We study supersymmetric branes in AdS_7 x S^4 and AdS_4 x S^7. We show that
in the former case the membranes should be viewed as M5 branes with fluxes and
we identify two types of such fivebranes (they are analogous to giant gravitons
and to dual giants). In AdS_4 x S^7 we find both M5 branes with fluxes and
freestanding stacks of membranes. We also go beyond probe approximation and
construct regular supergravity solutions describing geometries produced by the
branes. The metrics are completely specified by one function which satisfies
either Laplace or Toda equation and we give a complete classification of
boundary conditions leading to smooth geometries. The brane configurations
discussed in this paper are dual to various defects in three- and
six-dimensional conformal field theories.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 20:17:31 GMT"
},
{
"version": "v2",
"created": "Sun, 29 Jul 2007 00:18:50 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Lunin",
"Oleg",
""
]
] |
0704.3443 | Daniel Krashen | Daniel Krashen | Corestrictions of algebras and splitting fields | 13 pages | null | null | null | math.RA | null | Given a field $F$, an \'etale extension $L/F$ and an Azumaya algebra $A/L$,
one knows that there are extensions $E/F$ such that $A \otimes_F E$ is a split
algebra over $L \otimes_F E$. In this paper we bound the degree of a minimal
splitting field of this type from above and show that our bound is sharp in
certain situations, even in the case where $L/F$ is a split extension. This
gives in particular a number of generalizations of the classical fact that when
the tensor product of two quaternion algebras is not a division algebra, the
two quaternion algebras must share a common quadratic splitting field.
In another direction, our constructions combined with results of Karpenko
also show that for any odd prime number $p$, the generic algebra of index
$p^n$, and exponent $p$ cannot be expressed nontrivially as the corestriction
of an algebra over any extension field if $n < p^2$.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 20:20:33 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Krashen",
"Daniel",
""
]
] |
0704.3444 | Alexander J. Wagner | Qun Li, A.J. Wagner | A Symmetric Free Energy Based Multi-Component Lattice Boltzmann Method | 7 pager, 4 figures | null | 10.1103/PhysRevE.76.036701 | null | cond-mat.soft | null | We present a lattice Boltzmann algorithm based on an underlying free energy
that allows the simulation of the dynamics of a multicomponent system with an
arbitrary number of components. The thermodynamic properties, such as the
chemical potential of each component and the pressure of the overall system,
are incorporated in the model. We derived a symmetrical convection diffusion
equation for each component as well as the Navier Stokes equation and
continuity equation for the overall system. The algorithm was verified through
simulations of binary and ternary systems. The equilibrium concentrations of
components of binary and ternary systems simulated with our algorithm agree
well with theoretical expectations.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 16:22:22 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Li",
"Qun",
""
],
[
"Wagner",
"A. J.",
""
]
] |
0704.3445 | Jean Ruiz | Nicolae Angelescu (NIPNE), Robert Minlos (IITP), Jean Ruiz (CPT),
Valentin Zagrebnov (CPT) | Lower Spectral Branches of a Spin-Boson Model | null | Journal of Mathematical Physics 49 (2008) 102105 | 10.1063/1.2987721 | null | cond-mat.stat-mech math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the structure of the spectrum of a two-level quantum system weakly
coupled to a boson field (spin-boson model). Our analysis allows to avoid the
cutoff in the number of bosons, if their spectrum is bounded below by a
positive constant. We show that, for small coupling constant, the lower part of
the spectrum of the spin-boson Hamiltonian contains (one or two) isolated
eigenvalues and (respectively, one or two) manifolds of atom $+ 1$-boson states
indexed by the boson momentum $q$. The dispersion laws and generalized
eigenfunctions of the latter are calculated.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 20:34:32 GMT"
},
{
"version": "v2",
"created": "Tue, 28 Oct 2008 13:14:35 GMT"
}
] | 2008-10-28T00:00:00 | [
[
"Angelescu",
"Nicolae",
"",
"NIPNE"
],
[
"Minlos",
"Robert",
"",
"IITP"
],
[
"Ruiz",
"Jean",
"",
"CPT"
],
[
"Zagrebnov",
"Valentin",
"",
"CPT"
]
] |
0704.3446 | Pearl Sandick | John Ellis, Keith A. Olive and Pearl Sandick | Phenomenology of GUT-less Supersymmetry Breaking | 35 pages, 9 figures; typos corrected, references added | JHEP 0706:079,2007 | 10.1088/1126-6708/2007/06/079 | CERN-PH-TH/2007-073, UMN-TH-2602/07, FTPI-MINN-07/15 | hep-ph astro-ph hep-ex | null | We study models in which supersymmetry breaking appears at an intermediate
scale, M_{in}, below the GUT scale. We assume that the soft
supersymmetry-breaking parameters of the MSSM are universal at M_{in}, and
analyze the morphology of the constraints from cosmology and collider
experiments on the allowed regions of parameter space as M_{in} is reduced from
the GUT scale. We present separate analyses of the (m_{1/2},m_0) planes for
tan(beta)=10 and tan(beta)=50, as well as a discussion of non-zero trilinear
couplings, A_0. Specific scenarios where the gaugino and scalar masses appear
to be universal below the GUT scale have been found in mirage-mediation models,
which we also address here. We demand that the lightest neutralino be the LSP,
and that the relic neutralino density not conflict with measurements by WMAP
and other observations. At moderate values of M_{in}, we find that the allowed
regions of the (m_{1/2},m_0) plane are squeezed by the requirements of
electroweak symmetry breaking and that the lightest neutralino be the LSP,
whereas the constraint on the relic density is less severe. At very low M_{in},
the electroweak vacuum conditions become the dominant constraint, and a
secondary source of astrophysical cold dark matter would be necessary to
explain the measured relic density for nearly all values of the soft
SUSY-breaking parameters and tan(beta). We calculate the neutralino-nucleon
cross sections for viable scenarios and compare them with the present and
projected limits from direct dark matter searches.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 17:55:32 GMT"
},
{
"version": "v2",
"created": "Tue, 7 Aug 2007 12:44:32 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Ellis",
"John",
""
],
[
"Olive",
"Keith A.",
""
],
[
"Sandick",
"Pearl",
""
]
] |
0704.3447 | Barak Fishbain | Barak Fishbain, Leonid P. Yaroslavsky, Ianir A. Ideses | Real Time Turbulent Video Perfecting by Image Stabilization and
Super-Resolution | Submitted to The Seventh IASTED International Conference on
Visualization, Imaging, and Image Processing (VIIP 2007) August, 2007 Palma
de Mallorca, Spain | null | 10.1007/s11554-007-0037-x | null | physics.optics | null | Image and video quality in Long Range Observation Systems (LOROS) suffer from
atmospheric turbulence that causes small neighbourhoods in image frames to
chaotically move in different directions and substantially hampers visual
analysis of such image and video sequences. The paper presents a real-time
algorithm for perfecting turbulence degraded videos by means of stabilization
and resolution enhancement. The latter is achieved by exploiting the turbulent
motion. The algorithm involves generation of a reference frame and estimation,
for each incoming video frame, of a local image displacement map with respect
to the reference frame; segmentation of the displacement map into two classes:
stationary and moving objects and resolution enhancement of stationary objects,
while preserving real motion. Experiments with synthetic and real-life
sequences have shown that the enhanced videos, generated in real time, exhibit
substantially better resolution and complete stabilization for stationary
objects while retaining real motion.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 20:36:01 GMT"
}
] | 2010-07-27T00:00:00 | [
[
"Fishbain",
"Barak",
""
],
[
"Yaroslavsky",
"Leonid P.",
""
],
[
"Ideses",
"Ianir A.",
""
]
] |
0704.3448 | Steve Gonek | S. M. Gonek | Finite Euler products and the Riemann Hypothesis | 4 figures | null | null | null | math.NT math.CV | null | We show that if the Riemann Hypothesis is true, then in a region containing
most of the right-half of the critical strip, the Riemann zeta-function is well
approximated by short truncations of its Euler product. Conversely, if the
approximation by products is good in this region, the zeta-function has at most
finitely many zeros in it. We then construct a parameterized family of
non-analytic functions with this same property. With the possible exception of
a finite number of zeros off the critical line, every function in the family
satisfies a Riemann Hypothesis. Moreover, when the parameter is not too large,
they have about the same number of zeros as the zeta-function, their zeros are
all simple, and they "repel". The structure of these functions makes the reason
for the simplicity and repulsion of their zeros apparent and suggests a
mechanism that might be responsible for the corresponding properties of the
zeta-function's zeros. Computer evidence suggests that the zeros of functions
in the family are remarkably close to those of the zeta-function (even for
small values of the parameter), and we show that they indeed converge to them
as the parameter increases. Furthermore, between zeros of the zeta-function,
the moduli of functions in the family tend to twice the modulus of the
zeta-function. Both assertions assume the Riemann Hypothesis. We end by
discussing analogues for other L-functions and show how they give insight into
the study of the distribution of zeros of linear combinations of L-functions.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 18:21:22 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Gonek",
"S. M.",
""
]
] |
0704.3449 | Sergey Fedosov | A. F. Butenko, S. N. Fedosov, A. E. Sergeeva | Trapping of Compensating Charges in Corona Poled PVDF Films | 6 pages, 4 figures | null | null | null | cond-mat.mtrl-sci | null | Experimental evidence is provided on close relation between polarization and
space charge in corona poled PVDF films. It is shown that the depolarizing
field is compensated by charges trapped in macroscopic transition zones, by
which polarized parts of the volume are separated from non-polarized ones. The
compensating charges are either injected in the bulk, or created inside due to
the thermal emission and then trapped when the ferroelectric polarization in
crystallites is formed.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 21:11:51 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Butenko",
"A. F.",
""
],
[
"Fedosov",
"S. N.",
""
],
[
"Sergeeva",
"A. E.",
""
]
] |
0704.3450 | Esther Beneish | Esther Beneish | The center of the generic algebra of degree p | I am withdrawing this article | null | null | null | math.RA math.RT | null | Let $F$ be an algebraically closed field of characteristic zero, and let $p$
be an odd prime. We show that the center of the generic division algebra of
degree $p$ is stably rational over $F$. Equivalently, if we let $V=M_p(F)
\oplus M_p(F)$ and $PGL_p$ act on $V$ by simultaneous conjugation, then we show
that the function field of the quotient variety $V/PGL_p$ is stably rational
over $F$.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 21:12:23 GMT"
},
{
"version": "v2",
"created": "Thu, 7 Jun 2007 16:32:06 GMT"
},
{
"version": "v3",
"created": "Mon, 26 Mar 2012 22:17:06 GMT"
}
] | 2012-03-28T00:00:00 | [
[
"Beneish",
"Esther",
""
]
] |
0704.3451 | Denis Demchenko | Denis O. Demchenko and Lin-Wang Wang | Localized Electron States Near a Metal-Semiconductor Nanocontact | 11 pages 4 figures | null | 10.1021/nl072027n | null | cond-mat.mtrl-sci cond-mat.other | null | The electronic structure of nanowires in contact with metallic electrodes of
experimentally relevant sizes is calculated by incorporating the electrostatic
polarization potential into the atomistic single particle Schr\"odinger
equation. We show that the presence of an electrode produces localized
electron/hole states near the electrode, a phenomenon only exhibited in
nanostructures and overlooked in the past. This phenomenon will have profound
implications on electron transport in such nanosystems. We calculate several
electrode/nanowire geometries, with varying contact depths and nanowire radii.
We demonstrate the change in the band gap of up to 0.5 eV in 3 nm diameter CdSe
nanowires and calculate the magnitude of the applied electric field necessary
to overcome the localization.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 21:18:35 GMT"
}
] | 2015-05-13T00:00:00 | [
[
"Demchenko",
"Denis O.",
""
],
[
"Wang",
"Lin-Wang",
""
]
] |
0704.3452 | David Adams | D.A. Adams, B. Schmittmann, and R.K.P. Zia | Coarsening of "clouds" and dynamic scaling in a far-from-equilibrium
model system | null | Phys. Rev. E 75, 041123 (2007) | 10.1103/PhysRevE.75.041123 | null | cond-mat.stat-mech | null | A two-dimensional lattice gas of two species, driven in opposite directions
by an external force, undergoes a jamming transition if the filling fraction is
sufficiently high. Using Monte Carlo simulations, we investigate the growth of
these jams ("clouds"), as the system approaches a non-equilibrium steady state
from a disordered initial state. We monitor the dynamic structure factor
$S(k_x,k_y;t)$ and find that the $k_x=0$ component exhibits dynamic scaling, of
the form $S(0,k_y;t)=t^\beta \tilde{S}(k_yt^\alpha)$. Over a significant range
of times, we observe excellent data collapse with $\alpha=1/2$ and $\beta=1$.
The effects of varying filling fraction and driving force are discussed.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 21:22:29 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Adams",
"D. A.",
""
],
[
"Schmittmann",
"B.",
""
],
[
"Zia",
"R. K. P.",
""
]
] |
0704.3453 | Tshilidzi Marwala | S. Mohamed, D. Rubin, and T. Marwala | An Adaptive Strategy for the Classification of G-Protein Coupled
Receptors | 9 pages, 5 tables, 3 figures | null | null | null | cs.AI q-bio.QM | null | One of the major problems in computational biology is the inability of
existing classification models to incorporate expanding and new domain
knowledge. This problem of static classification models is addressed in this
paper by the introduction of incremental learning for problems in
bioinformatics. Many machine learning tools have been applied to this problem
using static machine learning structures such as neural networks or support
vector machines that are unable to accommodate new information into their
existing models. We utilize the fuzzy ARTMAP as an alternate machine learning
system that has the ability of incrementally learning new data as it becomes
available. The fuzzy ARTMAP is found to be comparable to many of the widespread
machine learning systems. The use of an evolutionary strategy in the selection
and combination of individual classifiers into an ensemble system, coupled with
the incremental learning ability of the fuzzy ARTMAP is proven to be suitable
as a pattern classifier. The algorithm presented is tested using data from the
G-Coupled Protein Receptors Database and shows good accuracy of 83%. The system
presented is also generally applicable, and can be used in problems in genomics
and proteomics.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 21:23:31 GMT"
}
] | 2007-06-25T00:00:00 | [
[
"Mohamed",
"S.",
""
],
[
"Rubin",
"D.",
""
],
[
"Marwala",
"T.",
""
]
] |
0704.3454 | Diana Valencia | Diana Valencia (1), Dimitar D. Sasselov (2), and Richard J. O'Connell
(1); ((1) Earth and Planetary Sciences Dept., Harvard University; (2)
Harvard-Smithsonian Center for Astrophysics) | Detailed Models of super-Earths: How well can we infer bulk properties? | 21 Pages, 5 figures. This article will appear in Astrophysical
Journal (around September) | Astrophys.J.665:1413-1420,2007 | 10.1086/519554 | null | astro-ph | null | The field of extrasolar planets has rapidly expanded to include the detection
of planets with masses smaller than that of Uranus. Many of these are expected
to have little or no hydrogen and helium gas and we might find Earth analogs
among them. In this paper we describe our detailed interior models for a rich
variety of such massive terrestrial and ocean planets in the 1-to-10 earth-mass
range (super-Earths). The grid presented here allows the characterization of
the bulk composition of super-Earths detected in transit and with a measured
mass. We show that, on average, planet radius measurements to better than 5%,
combined with mass measurements to better than 10% would permit us to
distinguish between an icy or rocky composition. This is due to the fact that
there is a maximum radius a rocky terrestrial planet may achieve for a given
mass. Any value of the radius above this maximum terrestrial radius implies
that the planet contains a large (> 10%) amount of water (ocean planet).
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 21:35:48 GMT"
},
{
"version": "v2",
"created": "Wed, 9 May 2007 19:36:56 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Valencia",
"Diana",
""
],
[
"Sasselov",
"Dimitar D.",
""
],
[
"O'Connell",
"Richard J.",
""
],
[
";",
"",
""
]
] |
0704.3455 | Paul Martini | Paul Martini (Ohio State), John S. Mulchaey, Daniel D. Kelson
(Carnegie Observatories) | The Distribution of AGN in Clusters of Galaxies | ApJ accepted, 16 pages, 10 figs, eTable 2 and high-res version
available at
http://www.astronomy.ohio-state.edu/~martini/professional/publications/index.html
Updated to match published version | Astrophys.J.664:761-776,2007 | 10.1086/519158 | null | astro-ph | null | We present a study of the distribution of AGN in clusters of galaxies with a
uniformly selected, spectroscopically complete sample of 35 AGN in eight
clusters at z = 0.06 to 0.31. We find that the 12 AGN with L_X > 10^42 erg/s in
galaxies more luminous than a rest-frame M_R < -20 mag are more centrally
concentrated than typical cluster galaxies of this luminosity, although these
AGN have comparable velocity and substructure distributions to other cluster
members. In contrast, a larger sample of 30 cluster AGN with L_X > 10^41 erg/s
do not show evidence for greater concentration than inactive members, nor
evidence for a different kinematic or substructure distribution. As we do see
clear differences in the spatial and kinematic distributions of the blue
Butcher-Oemler and red galaxy populations, any difference in the AGN and
inactive galaxy population must be less distinct than that between these two
pairs of populations. Comparison of the AGN fraction selected via X-ray
emission in this study to similarly-selected AGN in the field indicates that
the AGN fraction is not significantly lower in clusters, contrary to AGN
identified via visible-wavelength emission lines, but similar to the
approximately constant radio-selected AGN fraction in clusters and the field.
We also find significant evidence for variation between clusters and explore
the dependence of cluster AGN fraction on redshift, velocity dispersion,
cluster substructure, and Butcher-Oemler fraction. While we see weak evidence
for several trends, correlations between these four parameters in our small
sample precludes identification of which one(s) most strongly influence the
cluster AGN fraction.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 21:40:26 GMT"
},
{
"version": "v2",
"created": "Wed, 20 Jun 2007 17:40:23 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Martini",
"Paul",
"",
"Ohio State"
],
[
"Mulchaey",
"John S.",
"",
"Carnegie Observatories"
],
[
"Kelson",
"Daniel D.",
"",
"Carnegie Observatories"
]
] |
0704.3456 | Leandro Moral | Luis Velazquez | Spectral methods for orthogonal rational functions | 62 pages | null | null | null | math.CA | null | An operator theoretic approach to orthogonal rational functions on the unit
circle with poles in its exterior is presented in this paper. This approach is
based on the identification of a suitable matrix representation of the
multiplication operator associated with the corresponding orthogonality
measure. Two different alternatives are discussed, depending whether we use for
the matrix representation the standard basis of orthogonal rational functions,
or a new one with poles alternatively located in the exterior and the interior
of the unit circle. The corresponding representations are linear fractional
transformations with matrix coefficients acting respectively on Hessenberg and
five-diagonal unitary matrices.
In consequence, the orthogonality measure can be recovered from the spectral
measure of an infinite unitary matrix depending uniquely on the poles and the
parameters of the recurrence relation for the orthogonal rational functions.
Besides, the zeros of the orthogonal and para-orthogonal rational functions are
identified as the eigenvalues of matrix linear fractional transformations of
finite Hessenberg and five-diagonal matrices.
As an application of this operator approach, we obtain new relations between
the support of the orthogonality measure and the location of the poles and
parameters of the recurrence relation, generalizing to the rational case known
results for orthogonal polynomials on the unit circle.
Finally, we extend these results to orthogonal polynomials on the real line
with poles in the lower half plane.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 21:59:17 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Velazquez",
"Luis",
""
]
] |
0704.3457 | Dmitrii L. Maslov | Andrey V. Chubukov, Dmitrii L. Maslov | Cooper channel and the singularities in the thermodynamics of a Fermi
liquid | 5 pages, 1 figure | null | 10.1103/PhysRevB.76.165111 | null | cond-mat.str-el | null | We analyze how the logarithmic renormalizations in the Cooper channel affect
the non-analytic temperature dependence of the specific heat coefficient \gamma
(T) - \gamma (0)=A(T)T in a 2D Fermi liquid. We show that A(T) is expressed
exactly in terms of the fully renormalized backscattering amplitude which
includes the renormalization in the Cooper channel. In contrast to the 1D case,
both charge and spin components of the backscattering amplitudes are subject to
this renormalization. We show that the logarithmic renormalization of the
charge amplitude vanishes for a flat Fermi surface, when the system becomes
effectively one-dimensional.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 19:12:17 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Chubukov",
"Andrey V.",
""
],
[
"Maslov",
"Dmitrii L.",
""
]
] |
0704.3458 | Thomas G. Rizzo | Thomas G. Rizzo | Searching for Lee-Wick Gauge Bosons at the LHC | 17 pages, 4 figs; discussion added | JHEP 0706:070,2007 | 10.1088/1126-6708/2007/06/070 | SLAC-PUB-12481 | hep-ph astro-ph hep-ex | null | In an extension of the Standard Model(SM) based on the ideas of Lee and Wick,
Grinstein, O'Connell and Wise have found an interesting way to remove the usual
quadratically divergent contributions to the Higgs mass induced by radiative
corrections. Phenomenologically, the model predicts the existence of Terascale,
negative-norm copies of the usual SM fields with rather unique properties:
ghost-like propagators and negative decay widths, but with otherwise SM-like
couplings. The model is both unitary and causal on macroscopic scales. In this
paper we examine whether or not such states with these unusual properties can
be uniquely identified as such at the LHC. We find that in the extended strong
and electroweak gauge boson sector of the model, which is the simplest one to
analyze, such an identification can be rather difficult. Observation of heavy
gluon-like resonances in the dijet channel offers the best hope for this
identification.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 15:29:10 GMT"
},
{
"version": "v2",
"created": "Mon, 4 Jun 2007 15:04:07 GMT"
},
{
"version": "v3",
"created": "Mon, 11 Jun 2007 15:32:06 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Rizzo",
"Thomas G.",
""
]
] |
0704.3459 | Jonathan Rosner | Michael Gronau and Jonathan L. Rosner | Systematic Error on Weak Phase $\gamma$ from $B \to \pi^+ \pi^-$ and $B
\to K \pi$ | Comments and figure added | Phys.Lett.B651:166-170,2007 | 10.1016/j.physletb.2007.06.030 | TECHNION-PH-2007-14, EFI 07-13 | hep-ph hep-ex | null | When CP asymmetries in $B^0(t)\to \pi^+ \pi^-$ are combined using broken
flavor SU(3) with decay rates for $B^+\to K^0\pi^+$ and/or $B^0\to K^+\pi^-$,
one can obtain stringent limits on the weak phase $\gamma$ which are consistent
with those obtained from other CKM constraints. Experimental data in the past
few years have improved to the extent that systematic errors associated with
uncertainty in SU(3) symmetry breaking dominate the determination of $\gamma$.
We obtain a value $\gamma =(73 \pm 4^{+10}_{-8})^\circ$, where the first error
is statistical while the second one is systematic.
| [
{
"version": "v1",
"created": "Wed, 25 Apr 2007 23:07:33 GMT"
},
{
"version": "v2",
"created": "Sun, 29 Apr 2007 18:26:04 GMT"
},
{
"version": "v3",
"created": "Thu, 31 May 2007 09:37:45 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Gronau",
"Michael",
""
],
[
"Rosner",
"Jonathan L.",
""
]
] |
0704.3460 | Fu Jian | Jian Fu, Xiang Yin, and Limin Tong | Two-color atom guide and 1D optical lattice using evanescent fields of
high-order transverse modes | 18 pages, 12 figures, 1 table | null | 10.1088/0953-4075/40/21/007 | null | quant-ph | null | We propose a two-color scheme of atom guide and 1D optical lattice using
evanescent light fields of different transverse modes. The optical waveguide
carries a red-detuned light and a blue-detuned light, with both modes far from
resonance. The atom guide and 1D optical lattice potentials can be transformed
to each other by using a Mach-Zehnder interferometer to accurately control mode
transformation. This might provide a new approach to realize flexible
transition between the guiding and trapping states of atoms.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 01:05:34 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Fu",
"Jian",
""
],
[
"Yin",
"Xiang",
""
],
[
"Tong",
"Limin",
""
]
] |
0704.3461 | Su Houng Lee | Su Houng Lee and Takumi Doi | The vector-scalar mixing in nuclear medium and the two quark component
of scalar meson from QCD sum rules | 11 pages, 2 figures | null | null | null | nucl-th | null | We derive the QCD sum rules for the vector and scalar meson mixing in nuclear
medium, using a two quark interpolating field for both mesons. Modeling the
mixing via a nucleon hole contribution with known coupling constant, the sum
rule can be used to determine the overlap of the interpolating field and the
scalar meson. In the I=0 channel, we find a stable Borel curve and an overlap
that is about 10% of the corresponding value in the pseudo scalar or vector
channel. The sum rule in the I=1 channel is less reliable but also consistent
with a small value for the overlap. These results suggest that both the
$\sigma$ and $a_0$ have a small two quark and thus probably a large tetraquark
components. We discuss the possibility of observing these scalar mesons from
vector mesons emanating from the nuclear medium.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 01:33:49 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Lee",
"Su Houng",
""
],
[
"Doi",
"Takumi",
""
]
] |
0704.3462 | Pavel Yu. Moshin | P.Yu. Moshin, J.L. Tomazelli | On the Non-relativistic Limit of Linear Wave Equations for Zero and
Unity Spin Particles | 10 pages | Mod.Phys.Lett.A23:129-137,2008 | 10.1142/S0217732308023803 | null | hep-th | null | The non-relativistic limit of the linear wave equation for zero and unity
spin bosons of mass $m$ in the Duffin-Kemmer-Petiau representation is
investigated by means of a unitary transformation, analogous to the
Foldy-Wouthuysen canonical transformation for a relativistic electron. The
interacting case is also analyzed, by considering a power series expansion of
the transformed Hamiltonian, thus demonstrating that all features of particle
dynamics can be recovered if corrections of order $1/m^{2}$ are taken into
account through a recursive iteration procedure.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 02:39:32 GMT"
},
{
"version": "v2",
"created": "Fri, 11 May 2007 23:43:47 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Moshin",
"P. Yu.",
""
],
[
"Tomazelli",
"J. L.",
""
]
] |
0704.3463 | L. C. Wang | L. C. Wang, X. L. Huang and X. X. Yi | Landau-Zener transition of a two-level system driven by spin chains near
their critical points | 5 pages, 4 figures. European Physical Journals D accepted | null | 10.1140/epjd/e2007-00286-2 | null | quant-ph | null | The Landau-Zener(LZ) transition of a two-level system coupling to spin chains
near their critical points is studied in this paper. Two kinds of spin chains,
the Ising spin chain and XY spin chain, are considered. We calculate and
analyze the effects of system-chain coupling on the LZ transition. A relation
between the LZ transition and the critical points of the spin chain is
established. These results suggest that LZ transitions may serve as the
witnesses of criticality of the spin chain. This may provide a new way to study
quantum phase transitions as well as LZ transitions.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 01:58:35 GMT"
},
{
"version": "v2",
"created": "Thu, 20 Sep 2007 00:19:12 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Wang",
"L. C.",
""
],
[
"Huang",
"X. L.",
""
],
[
"Yi",
"X. X.",
""
]
] |
0704.3464 | Robert Shrock | Robert Shrock | Constraints on $N_c$ in Extensions of the Standard Model | 4 pages, revtex | Phys.Rev.D76:055010,2007 | 10.1103/PhysRevD.76.055010 | YITP-SB-07-16 | hep-th hep-ph | null | We consider a class of theories involving an extension of the Standard Model
gauge group to an {\it a priori} arbitrary number of colors, $N_c$, and derive
constraints on $N_c$. One motivation for this is the string theory landscape.
For two natural classes of embeddings of this $N_c$-extended Standard Model in
a supersymmetric grand unified theory, we show that requiring unbroken
electromagnetic gauge invariance, asymptotic freedom of color, and three
generations of quarks and leptons forces one to choose $N_c=3$. Similarly, we
show that for a theory combining the $N_c$-extended Standard Model with a
one-family SU(2)$_{TC}$ technicolor theory, only the value $N_c=3$ is allowed.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 02:03:55 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Shrock",
"Robert",
""
]
] |
0704.3465 | Antonio Pulido Paton | Antonio Pulido Paton | Current prospects for ASTROD Inertial Sensor | 22 pages, 1 figure. Accepted for publication in International Journal
of Modern Physics D | Int.J.Mod.Phys.D17:941-963,2008 | 10.1142/S0218271808012620 | null | gr-qc | null | The Astrodynamical Space Test of Relativity using Optical Devices (ASTROD) is
a multi-purpose relativity mission concept. ASTROD's scientific goals are the
measurement of relativistic and solar system parameters to unprecedented
precision, and the detection and observation of low-frequency gravitational
waves to frequencies down to $5\times10^{-6}$ Hz. To accomplish its goals,
ASTROD will employ a constellation of drag-free satellites, aiming for a
residual acceleration noise of (0.3-1)$\times$ 10$^{-15}$ m s$^{-2}$
Hz$^{-1/2}$ at 0.1 mHz. Noise sources and strategies for improving present
acceleration noise levels are reported.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 09:50:32 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Paton",
"Antonio Pulido",
""
]
] |
0704.3466 | Alexander Bolonkin | Alexander Bolonkin | Optimal Electrostatic Space Tower (Mast, New Space Elevator) | 11 pages, 6 figures, 3 tables | null | null | null | physics.gen-ph physics.space-ph | null | Author offers and researched the new and revolutionary inflatable
electrostatic AB space towers (mast, new space elevator) up to one hundred
twenty thousands kilometers (or more) in height. The main innovation is filling
the tower by electron gas, which can create pressure up one atmosphere, has
negligible small weight and surprising properties.
The suggested mast has following advantages in comparison with conventional
space elevator: 1. Electrostatic AB tower may be built from Earth surface
without the employment of any rockets. That decreases the cost of electrostatic
mast by thousands of times. 2. One can have any height and has a big control
load capacity. 3. Electrostatic tower can have the height of a geosynchronous
orbit (36,000 km) WITHOUT the additional top cable as the space elevator (up
120,000 - 160,000 km) and counterweight (equalizer) of hundreds of tons. 4. The
offered mast has less total mass than conventional space elevator. 5. The
offered tower can have the high-speed electrostatic climbers moved by
high-voltage electricity from Earth's surface. 6. The electrostatic mast can
bend in any needed direction when we give the necessary electric voltage in the
required parts of the extended mast. 7. Control mast has stability for any
altitude. Three projects 100 km, 36,000km (GEO), 120,000 km are computed and
presented.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 02:54:59 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Bolonkin",
"Alexander",
""
]
] |
0704.3467 | Kunihito Ioka | Kunihito Ioka, Hiroyuki Nakano | Second and higher-order quasi-normal modes in binary black hole mergers | 5 pages, 1 figure, accepted for publication in PRD Rapid
Communications | Phys.Rev.D76:061503,2007 | 10.1103/PhysRevD.76.061503 | null | astro-ph gr-qc | null | Black hole (BH) oscillations known as quasi-normal modes (QNMs) are one of
the most important gravitational wave (GW) sources. We propose that higher
perturbative order of QNMs, generated by nonlinear gravitational interaction
near the BHs, are detectable and worth searching for in observations and
simulations of binary BH mergers. We calculate the metric perturbations to
second-order and explicitly regularize the master equation at the horizon and
spatial infinity. We find that the second-order QNMs have frequencies twice the
first-order ones and the GW amplitude is up to ~10% that of the first-order
one. The QNM frequency would also shift blueward up to ~1%. This provides a new
test of general relativity as well as a possible distance indicator.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 02:59:25 GMT"
},
{
"version": "v2",
"created": "Wed, 13 Jun 2007 06:25:34 GMT"
},
{
"version": "v3",
"created": "Fri, 3 Aug 2007 04:43:34 GMT"
}
] | 2008-12-18T00:00:00 | [
[
"Ioka",
"Kunihito",
""
],
[
"Nakano",
"Hiroyuki",
""
]
] |
0704.3468 | Shu-Yu Hsu | Shu-Yu Hsu | Uniqueness of solutions of Ricci flow on complete noncompact manifolds | A simple example of a manifold with bounded curvature and injectivity
radius going to zero as the point tends to infinity is given. A proof and
argument why the crucial lemma Lemma 2.2 of the Chen-Zhu's paper \cite{CZ}
cannot hold is given | null | null | null | math.DG math.AP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We prove the uniqueness of solutions of the Ricci flow on complete noncompact
manifolds with bounded curvatures using the De Turck approach. As a consequence
we obtain a correct proof of the existence of solution of the Ricci harmonic
flow on complete noncompact manifolds with bounded curvatures.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 06:16:06 GMT"
},
{
"version": "v2",
"created": "Fri, 18 May 2007 02:37:47 GMT"
},
{
"version": "v3",
"created": "Tue, 10 Aug 2010 12:58:37 GMT"
},
{
"version": "v4",
"created": "Fri, 7 Oct 2011 05:55:47 GMT"
}
] | 2011-10-10T00:00:00 | [
[
"Hsu",
"Shu-Yu",
""
]
] |
0704.3469 | Brant Jones | Hugh Denoncourt and Brant C. Jones | The enumeration of maximally clustered permutations | 17 pages; corrected typos, added new section | null | null | null | math.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The maximally clustered permutations are characterized by avoiding the
classical permutation patterns 3421, 4312, and 4321. This class contains the
freely-braided permutations and the fully-commutative permutations. In this
work, we show that the generating functions for certain fully-commutative
pattern classes can be transformed to give generating functions for the
corresponding freely-braided and maximally clustered pattern classes. Moreover,
this transformation of generating functions is rational. As a result, we obtain
enumerative formulas for the pattern classes mentioned above as well as the
corresponding hexagon-avoiding pattern classes where the hexagon-avoiding
permutations are characterized by avoiding 46718235, 46781235, 56718234, and
56781234.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 16:49:32 GMT"
},
{
"version": "v2",
"created": "Thu, 25 Sep 2008 17:54:39 GMT"
}
] | 2008-09-25T00:00:00 | [
[
"Denoncourt",
"Hugh",
""
],
[
"Jones",
"Brant C.",
""
]
] |
0704.3470 | Courtney Mewton | C. J. Mewton and Z. Ficek | Radiative properties of a linear chain of coupled qubits | 20 pages, 11 figures | J. Phys. B: At. Mol. Opt. Phys. 40 (2007) S181-S197 | 10.1088/0953-4075/40/9/S11 | null | quant-ph | null | We calculate the radiative properties for a linear dipole-coupled chain of
qubits. Using the explicit energy eigenstates of the system, we find the
radiation patterns for spontaneous transitions from the one-photon eigenstates
to the ground state of the system. We show that depending on the excitation of
a specific atom, the radiation tends to be focused either along or
perpendicular to the chain. We conclude with a derivation of the total decay
rate of the one-photon eigenstates, and find the interesting result that for
systems where the photon wavenumber is not much larger than the interatomic
spacing, up to 94% of the eigenstates are subradiant, that is, they decay
significantly slower than a single atom in isolation.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 03:37:21 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Mewton",
"C. J.",
""
],
[
"Ficek",
"Z.",
""
]
] |
0704.3471 | Bernd Sturmfels | Bernd Sturmfels and Jenia Tevelev | Elimination Theory for Tropical Varieties | 19 pages | null | null | null | math.AG math.AC | null | Tropical algebraic geometry offers new tools for elimination theory and
implicitization. We determine the tropicalization of the image of a subvariety
of an algebraic torus under any homomorphism from that torus to another torus.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 04:01:49 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Sturmfels",
"Bernd",
""
],
[
"Tevelev",
"Jenia",
""
]
] |
0704.3472 | Hamed Moradi | H. Moradi, A. -C. Donea, C. Lindsey, D. Besliu-Ionescu and P. S. Cally | Helioseismic analysis of the solar flare-induced sunquake of 2005
January 15 | 12 pages, 7 figures, published in MNRAS | Mon.Not.Roy.Astron.Soc.374:1155-1163,2007 | 10.1111/j.1365-2966.2006.11234.x | null | astro-ph | null | We report the discovery of one of the most powerful sunquakes detected to
date, produced by an X1.2-class solar flare in active region 10720 on 2005
January 15. We used helioseismic holography to image the source of seismic
waves emitted into the solar interior from the site of the flare. Acoustic
egression power maps at 3 and 6 mHz with a 2 mHz bandpass reveal a compact
acoustic source strongly correlated with impulsive hard X-ray and
visible-continuum emission along the penumbral neutral line separating the two
major opposing umbrae in the $\delta$-configuration sunspot that predominates
AR10720. The acoustic emission signatures were directly aligned with both hard
X-ray and visible continuum emission that emanated during the flare. The
visible continuum emission is estimated at $2.0 \times 10^{23}$ J,
approximately 500 times the seismic emission of $\sim 4 \times 10^{20}$ J. The
flare of 2005 January 15 exhibits the same close spatial alignment between the
sources of the seismic emission and impulsive visible continuum emission as
previous flares, reinforcing the hypothesis that the acoustic emission may be
driven by heating of the low photosphere. However, it is a major exception in
that there was no signature to indicate the inclusion of protons in the
particle beams thought to supply the energy radiated by the flare. The
continued strong coincidence between the sources of seismic emission and
impulsive visible continuum emission in the case of a proton-deficient
white-light flare lends substantial support to the ``back -- warming''
hypothesis, that the low photosphere is significantly heated by intense Balmer
and Paschen continuum-edge radiation from the overlying chromosphere in
white-light flares.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 04:39:08 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Moradi",
"H.",
""
],
[
"Donea",
"A. -C.",
""
],
[
"Lindsey",
"C.",
""
],
[
"Besliu-Ionescu",
"D.",
""
],
[
"Cally",
"P. S.",
""
]
] |
0704.3473 | Matthew Johnson | Anthony Aguirre, Matthew C Johnson, Assaf Shomer | Towards observable signatures of other bubble universes | 17 PRD-style pages including 13 embedded figures. Minor corrections
to figures 4 and 7 and added discussion in Sec. III.E.2 and V | Phys.Rev.D76:063509,2007 | 10.1103/PhysRevD.76.063509 | null | hep-th astro-ph gr-qc | null | We evaluate the possibility of observable effects arising from collisions
between vacuum bubbles in a universe undergoing false-vacuum eternal inflation.
Contrary to conventional wisdom, we find that under certain assumptions most
positions inside a bubble should have access to a large number of collision
events. We calculate the expected number and angular size distribution of such
collisions on an observer's "sky," finding that for typical observers the
distribution is anisotropic and includes many bubbles, each of which will
affect the majority of the observer's sky. After a qualitative discussion of
the physics involved in collisions between arbitrary bubbles, we evaluate the
implications of our results, and outline possible detectable effects. In an
optimistic sense, then, the present paper constitutes a first step in an
assessment of the possible effects of other bubble universes on the cosmic
microwave background and other observables.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 05:16:39 GMT"
},
{
"version": "v2",
"created": "Tue, 15 May 2007 22:44:25 GMT"
},
{
"version": "v3",
"created": "Wed, 25 Jul 2007 13:30:54 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Aguirre",
"Anthony",
""
],
[
"Johnson",
"Matthew C",
""
],
[
"Shomer",
"Assaf",
""
]
] |
0704.3474 | Tshilidzi Marwala | Fulufhelo V. Nelwamondo, Shakir Mohamed and Tshilidzi Marwala | Missing Data: A Comparison of Neural Network and Expectation
Maximisation Techniques | 24 pages, 7 figures, 4 tables | null | null | null | stat.AP | null | The estimation of missing input vector elements in real time processing
applications requires a system that possesses the knowledge of certain
characteristics such as correlations between variables, which are inherent in
the input space. Computational intelligence techniques and maximum likelihood
techniques do possess such characteristics and as a result are important for
imputation of missing data. This paper compares two approaches to the problem
of missing data estimation. The first technique is based on the current state
of the art approach to this problem, that being the use of Maximum Likelihood
(ML) and Expectation Maximisation (EM. The second approach is the use of a
system based on auto-associative neural networks and the Genetic Algorithm as
discussed by Adbella and Marwala3. The estimation ability of both of these
techniques is compared, based on three datasets and conclusions are made.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 05:03:08 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Nelwamondo",
"Fulufhelo V.",
""
],
[
"Mohamed",
"Shakir",
""
],
[
"Marwala",
"Tshilidzi",
""
]
] |
0704.3475 | Anatoly Ivanov | A.A. Ivanov | On UHECR energy estimation algorithms based on the measurement of
electromagnetic component parameters in EAS | contracted version is accepted for publication in Doklady Physics | Doklady Physics, vol. 52, no.10, p.523-526 (2007) | 10.1134/S1028335807100035 | null | astro-ph | null | Model calculations are performed of extensive air shower (EAS) component
energies using a variety of hadronic interaction parameters. A conversion
factor from electromagnetic component energy to the energy of ultra-high energy
cosmic rays (UHECRs) and its model and primary mass dependence is studied. It
is shown that model dependence of the factor minimizes under the necessary
condition of the same maximum position and muon content of simulated showers.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 05:09:07 GMT"
}
] | 2008-03-24T00:00:00 | [
[
"Ivanov",
"A. A.",
""
]
] |
0704.3476 | Masamichi Ishihara | Masamichi Ishihara | Suppression of growth by multiplicative white noise in a parametric
resonant system | The title and the description in the manuscript are changed | Brazilian Journal of Physics 45, 112-119 (2015) | 10.1007/s13538-014-0290-y | null | cond-mat.stat-mech cond-mat.other | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The author studied the growth of the amplitude in a Mathieu-like equation
with multiplicative white noise. The approximate value of the exponent at the
extremum on parametric resonance regions was obtained theoretically by
introducing the width of time interval, and the exponents were calculated
numerically by solving the stochastic differential equations by a symplectic
numerical method. The Mathieu-like equation contains a parameter $\alpha$ that
is determined by the intensity of noise and the strength of the coupling
between the variable and the noise. The value of $\alpha$ was restricted not to
be negative without loss of generality. It was shown that the exponent
decreases with $\alpha$, reaches a minimum and increases after that. It was
also found that the exponent as a function of $\alpha$ has only one minimum at
$\alpha \neq 0$ on parametric resonance regions of $\alpha = 0$. This minimum
value is obtained theoretically and numerically. The existence of the minimum
at $\alpha \neq 0$ indicates the suppression of the growth by multiplicative
white noise.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 05:17:51 GMT"
},
{
"version": "v2",
"created": "Tue, 25 Sep 2007 05:37:28 GMT"
},
{
"version": "v3",
"created": "Wed, 27 Feb 2008 03:30:39 GMT"
},
{
"version": "v4",
"created": "Tue, 23 Jun 2009 04:47:37 GMT"
},
{
"version": "v5",
"created": "Thu, 12 Nov 2009 04:34:38 GMT"
},
{
"version": "v6",
"created": "Mon, 14 Jun 2010 07:55:48 GMT"
},
{
"version": "v7",
"created": "Fri, 28 Oct 2011 11:12:08 GMT"
}
] | 2017-12-12T00:00:00 | [
[
"Ishihara",
"Masamichi",
""
]
] |
0704.3477 | Selcuk Bilir | S. Ak, S. Bilir, S. Karaali, R. Buser, A. Cabrera-Lavers | The metallicity distributions in high-latitudes with SDSS | 14 pages, 7 figures and 2 tables, accepted for publication in New
Astronomy | NewAstron.12:605-612,2007 | 10.1016/j.newast.2007.04.005 | null | astro-ph | null | We present metallicities and their variations with different parameters for
36 high-latitude fields covering Galactic longitudes 0<l<360. The metallicities
for relatively short vertical distances (z<2.5 kpc) show systematic
fluctuations with Galactic longitude, similar to those of the thick-disc
scaleheight, which may be interpreted as indicating a common origin, viz., the
flare effect of the disc. This suggestion is supported by the metallicity
variations which we find as functions of radial distance. The metallicity
variation at larger vertical distances (6.5<z<9.5 kpc) is small but monotonic.
Three different vertical metallicity gradients could be detected:
d[M/H]/dz=-0.22(+/-0.03), d[M/H]/dz=-0.38 (+/-0.06), and d[M/H]/dz=-0.08
(+/-0.07) dex/kpc for the intervals z<3, 3<z<5, and 5<z<10 kpc, respectively.
Since our data cover the whole Galactic longitude interval, the resulting
metallicity gradients can be interpreted as properties of the larger-scale
Galaxy. The first gradient confirms the dissipational formation of the disc at
short z-distances. The steeper gradient corresponds to the transition region
between different population components of the Galaxy, and finally, the lowest
value provides an adequate description of the inner-halo metallicity gradient.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 06:03:36 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Ak",
"S.",
""
],
[
"Bilir",
"S.",
""
],
[
"Karaali",
"S.",
""
],
[
"Buser",
"R.",
""
],
[
"Cabrera-Lavers",
"A.",
""
]
] |
0704.3478 | Pengfei Lan | Pengfei Lan, Peixiang Lu, Wei Cao, Yuhua Li, Xinlin Wang | Isolated sub-100-attosecond pulse generation via controlling electron
dynamics | 11 pages, 4 figures | PhysRevA.76.011402 (2007) | 10.1103/PhysRevA.76.011402 | null | physics.atom-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A new method to coherently control the electron dynamics is proposed using a
few-cycle laser pulse in combination with a controlling field. It is shown that
this method not only broadens the attosecond pulse bandwidth, but also reduces
the chirp, then an isolated 80-as pulse is straightforwardly obtained and even
shorter pulse is achievable by increasing the intensity of the controlling
field. Such ultrashort pulses allow one to investigate ultrafast electronic
processes which have never be achieved before. In addition, the few-cycle
synthesized pulse is expected to manipulate a wide range of laser-atom
interactions.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 06:32:54 GMT"
},
{
"version": "v2",
"created": "Thu, 10 Jul 2008 12:51:03 GMT"
}
] | 2015-04-06T00:00:00 | [
[
"Lan",
"Pengfei",
""
],
[
"Lu",
"Peixiang",
""
],
[
"Cao",
"Wei",
""
],
[
"Li",
"Yuhua",
""
],
[
"Wang",
"Xinlin",
""
]
] |
0704.3479 | Ghi Shin R. | Ghi R. Shin | Elliptic Flow and Jet Quenching of a Parton System after Relativistic
Heavy Ion Collision | 14 pages, applied for J. Korean Physical Society | null | 10.3938/jkps.51.18 | null | nucl-th | null | We obtain the initial phase space distribution after relativistic heavy ion
collision by the CGC shattering method incorporating the uncertainty principle
and solve the semi-classical Boltzmann equation which includes the gluon
radiation processes. We present as a function of time the attenuation rate of
high $p_T$ partons, which have transverse momenta over 6 $GeV/c$, in the medium
which is formed after relativistic heavy ion collision. We calculate the
elliptic flow as a function of an impact parameter, time and transverse
momentum and also present the polar anisotropy, which gives the initial
condition for color filamentation.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 06:43:11 GMT"
}
] | 2015-05-13T00:00:00 | [
[
"Shin",
"Ghi R.",
""
]
] |
0704.3480 | Anisia Tang Pui Shan | A. Y. L. Wong, Y. F. Huang, K. S. Cheng | Transient X-ray Emission from Normal Galactic Nuclei | 5 figures, accepted by A&A | Astron.Astrophys.472:93,2007 | 10.1051/0004-6361:20077222 | null | astro-ph | null | X-ray transients appeared in optically non-active galactic nuclei have been
observed in recent years. The most popular model explaining this kind of
phenomena is the conventional tidal disruption model. In this model, when a
star moves within the tidal radius of a black hole, part of the star materials
will fall into the black hole through an accretion disk, which gives rise to
the luminous flare. We propose that the X-ray emission may not necessarily come
from radiation of the accretion disk alone. Instead, it may be related to a
jet. As the jet travels in the interstellar medium, a shock is produced and
synchrotron radiation is expected. We compared the model light curve and the
synchrotron radiation spectrum with the observed data, and find that our model
explains the observed light curve and late-time spectrum well. Our model
predicts that these transient active galactic nuclei could be sources of the
future gamma-ray satellites, e.g. GLAST and the emission region will be
expanding with time.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 07:01:59 GMT"
},
{
"version": "v2",
"created": "Mon, 30 Apr 2007 07:35:51 GMT"
},
{
"version": "v3",
"created": "Tue, 12 Jun 2007 08:19:16 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Wong",
"A. Y. L.",
""
],
[
"Huang",
"Y. F.",
""
],
[
"Cheng",
"K. S.",
""
]
] |
0704.3481 | Masafumi Kurachi | Masafumi Kurachi, Robert Shrock, Koichi Yamawaki | Z Boson Propagator Correction in Technicolor Theories with ETC Effects
Included | 15pages, 8 figures | Phys.Rev.D76:035003,2007 | 10.1103/PhysRevD.76.035003 | YITP-SB-07-07 | hep-ph | null | We calculate the Z boson propagator correction, as described by the S
parameter, in technicolor theories with extended technicolor interactions
included. Our method is to solve the Bethe-Salpeter equation for the requisite
current-current correlation functions. Our results suggest that the inclusion
of extended technicolor interactions has a relatively small effect on S.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 07:06:41 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Kurachi",
"Masafumi",
""
],
[
"Shrock",
"Robert",
""
],
[
"Yamawaki",
"Koichi",
""
]
] |
0704.3482 | Sagar Chakraborty Mr. | Sagar Chakraborty, Partha Guha | On the MHD load and the MHD metage | Some issues in the paper are yet to be addressed. Constructive
critisicms are most welcome | Phys. Plasmas 15, 012112 (2008) | 10.1063/1.2836617 | null | physics.plasm-ph physics.flu-dyn | null | In analogy with the load and the metage in hydrodynamics, we define
magnetohydrodynamic load and magnetohydrodynamic metage in the case of
magnetofluids. They can be used to write the magnetic field in MHD in Clebsch's
form. We show how these two concepts can be utilised to derive the magnetic
analogue of the Ertel's theorem and also, how in the presence of non-trivial
topology of the magnetic field in the magnetofluid one may associate the
linking number of the magnetic field lines with the invariant MHD loads. The
paper illustrates that the symmetry translation of the MHD metage in the
corresponding label space generates the conservation of cross helicity.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 07:15:16 GMT"
}
] | 2015-05-13T00:00:00 | [
[
"Chakraborty",
"Sagar",
""
],
[
"Guha",
"Partha",
""
]
] |
0704.3483 | Arup Banerjee | Arup Banerjee | Collective oscillations of a Bose-Fermi mixture: Effect of unequal mass
of Bose and Fermi particles | 15 pages, 4 figures | null | 10.1103/PhysRevA.76.023611 | null | cond-mat.other cond-mat.mes-hall | null | We investigate the effect of different mass of a Bose- and a Fermi-particle
on the collective oscillations of the degenerate boson-fermion mixtures. In
particular we consider the monopole and the quadrupole modes of the
oscillations and study their characters and the frequencies by using
variational-sum-rule approach. We find that for both the modes there exists a
critical value of the ratio of boson-fermion mass below and above which the
character and the frequency of the respective modes are significantly
different.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 07:18:31 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Banerjee",
"Arup",
""
]
] |
0704.3484 | Chethan Krishnan | Jarah Evslin, Chethan Krishnan, Stanislav Kuperstein | Cascading Quivers from Decaying D-branes | 11 pages, 1 figure; v2: references added | JHEP0708:020,2007 | 10.1088/1126-6708/2007/08/020 | null | hep-th | null | We use an argument analogous to that of Kachru, Pearson and Verlinde to argue
that cascades in L^{a,b,c} quiver gauge theories always preserve the form of
the quiver, and that all gauge groups drop at each step by the number M of
fractional branes. In particular, we demonstrate that an NS5-brane that sweeps
out the S^3 of the base of L^{a,b,c} destroys M D3-branes.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 10:06:05 GMT"
},
{
"version": "v2",
"created": "Mon, 7 May 2007 16:08:53 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Evslin",
"Jarah",
""
],
[
"Krishnan",
"Chethan",
""
],
[
"Kuperstein",
"Stanislav",
""
]
] |
0704.3485 | Xing-Hao Ye | Xing-Hao Ye, Qiang Lin | A Simple Optical Analysis of Gravitational Lensing | 4 pages, 6 figures | null | 10.1080/09500340701618395 | null | gr-qc | null | We analyzed the influence of static gravitational field on the vacuum and
proposed the concept of inhomogeneous vacuum. According to the corresponding
Fermat's principle in the general relativity, we derived a graded refractive
index of vacuum in a static gravitational field. We found that the light
deflection in a gravitational field can be calculated correctly with the use of
this refractive index and therefore the gravitational lensing can be treated
conveniently with the optical method. For illustration, we simulated the
imaging of gravitational lensing, figured out the time delay between the two
images and calculated the lens mass in a conventional optical way.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 12:07:47 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Ye",
"Xing-Hao",
""
],
[
"Lin",
"Qiang",
""
]
] |
0704.3486 | Tilo Wettig | J. Bloch, A. Frommer, B. Lang, T. Wettig | An iterative method to compute the sign function of a non-Hermitian
matrix and its application to the overlap Dirac operator at nonzero chemical
potential | 11 pages, 4 figures; minor changes, as published in Comput. Phys.
Commun. | Comput.Phys.Commun.177:933-943,2007 | null | null | hep-lat | null | The overlap Dirac operator in lattice QCD requires the computation of the
sign function of a matrix. While this matrix is usually Hermitian, it becomes
non-Hermitian in the presence of a quark chemical potential. We show how the
action of the sign function of a non-Hermitian matrix on an arbitrary vector
can be computed efficiently on large lattices by an iterative method. A Krylov
subspace approximation based on the Arnoldi algorithm is described for the
evaluation of a generic matrix function. The efficiency of the method is
spoiled when the matrix has eigenvalues close to a function discontinuity. This
is cured by adding a small number of critical eigenvectors to the Krylov
subspace, for which we propose two different deflation schemes. The ensuing
modified Arnoldi method is then applied to the sign function, which has a
discontinuity along the imaginary axis. The numerical results clearly show the
improved efficiency of the method. Our modification is particularly effective
when the action of the sign function of the same matrix has to be computed many
times on different vectors, e.g., if the overlap Dirac operator is inverted
using an iterative method.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 19:56:21 GMT"
},
{
"version": "v2",
"created": "Fri, 19 Oct 2007 14:27:13 GMT"
}
] | 2016-02-09T00:00:00 | [
[
"Bloch",
"J.",
""
],
[
"Frommer",
"A.",
""
],
[
"Lang",
"B.",
""
],
[
"Wettig",
"T.",
""
]
] |
0704.3487 | Charles M. Marcus | J. R. Williams, L. DiCarlo, C. M. Marcus | Quantum Hall Effect in a Graphene p-n Junction | related papers at http://marcuslab.harvard.edu. Fixed a factor of 2
in Eq. 1 and 2 | Science 317, 638 (2007) | null | null | cond-mat.mes-hall cond-mat.mtrl-sci | null | We report on the fabrication and transport studies of a single-layer graphene
p-n junction. Carrier type and density in two adjacent regions are individually
controlled by electrostatic gating using a local top gate and a global back
gate. A functionalized Al203 oxide that adheres to graphene and does not
significantly affect its electronic properties is described. Measurements in
the quantum Hall regime reveal new plateaus of two-terminal conductance across
the junction at 1 and 3/2 times the quantum of conductance, e2/h, consistent
with theory.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 19:57:15 GMT"
},
{
"version": "v2",
"created": "Tue, 28 Aug 2007 17:18:04 GMT"
}
] | 2007-08-28T00:00:00 | [
[
"Williams",
"J. R.",
""
],
[
"DiCarlo",
"L.",
""
],
[
"Marcus",
"C. M.",
""
]
] |
0704.3488 | R.J. Vanderbei | R.J. Vanderbei, N.J. Kasdin, E. Cady | Optimal Occulter Design for Finding Extrasolar Planets | 14 pages, 4 figures, 15 subfigures | Astrophys.J.665:794-798,2007 | 10.1086/519452 | null | astro-ph | null | One proposed method for finding terrestrial planets around nearby stars is to
use two spacecraft--a telescope and a specially shaped occulter that is
specifically designed to prevent all but a tiny fraction of the starlight from
diffracting into the telescope. As the cost and observing cadence for such a
mission will be driven largely by the separation between the two spacecraft, it
is critically important to design an occulter that can meet the observing goals
while flying as close to the telescope as possible. In this paper, we explore
this tradeoff between separation and occulter diameter. More specifically, we
present a method for designing the shape of the outer edge of an occulter that
is as small as possible and gives a shadow that is deep enough and large enough
for a 4m telescope to survey the habitable zones of many stars for Earth-like
planets. In particular, we show that in order for a 4m telescope to detect in
broadband visible light a planet 0.06 arcseconds from a star shining $10^{10}$
times brighter than the planet requires a specially-shaped occulter 50m in
diameter positioned about $72,000$ km in front of the telescope.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 07:49:09 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Vanderbei",
"R. J.",
""
],
[
"Kasdin",
"N. J.",
""
],
[
"Cady",
"E.",
""
]
] |
0704.3489 | Pascal Degiovanni | Valentin Bonzom (Phys-ENS), Hichem Bouzidi (Phys-ENS), Pascal
Degiovanni (Phys-ENS, BU-PHYS) | Dissipative dynamics of circuit-QED in the mesoscopic regime | 10 figures, 1 table | European Physical Journal D 1, 47 (2008) 133 | 10.1140/epjd/e2008-00039-9 | null | quant-ph cond-mat.mes-hall | null | We investigate the behavior of a circuit QED device when the resonator is
initially populated with a mesoscopic coherent field. The strong coupling
between the cavity and the qubit produces an entangled state involving
mesoscopic quasi-pointer states with respect to cavity dissipation. The overlap
of the associated field components results in collapse and revivals for the
Rabi oscillation. Although qubit relaxation and dephasing do not preserve these
states, a simple analytical description of the dissipative dynamics of the
circuit QED device including cavity relaxation as well as qubit dissipation is
obtained from the Monte-Carlo approach. Explicit predictions for the
spontaneous and induced Rabi oscillation signals are derived and sucessfully
compared with exact calculations. We show that these interesting effects could
be observed with a 10 photon field in forthcoming circuit QED experiments.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 07:57:20 GMT"
}
] | 2008-04-16T00:00:00 | [
[
"Bonzom",
"Valentin",
"",
"Phys-ENS"
],
[
"Bouzidi",
"Hichem",
"",
"Phys-ENS"
],
[
"Degiovanni",
"Pascal",
"",
"Phys-ENS, BU-PHYS"
]
] |
0704.3490 | Rossella Cassano | R. Cassano, G. Brunetti, G. Setti, F. Govoni, K. Dolag | New scaling relations in cluster radio halos and the re-acceleration
model | 11 pages, 12 figures, accepted for publication in MNRAS | Mon.Not.Roy.Astron.Soc.378:1565-1574,2007 | 10.1111/j.1365-2966.2007.11901.x | null | astro-ph | null | In this paper we derive new expected scaling relations for clusters with
giant radio halos in the framework of the re-acceleration scenario in a
simplified, but physically motivated, form, namely: radio power (P_R) vs size
of the radio emitting region (R_H), and P_R vs total cluster mass (M_H)
contained in the emitting region and cluster velocity dispersion (sigma_H) in
this region.
We search for these correlations by analyzing the most recent radio and X-ray
data available in the literature for a well known sample of clusters with giant
radio halos. In particular we find a good correlation between P_R and R_H and a
very tight ``geometrical'' scaling between M_H and R_H. From these correlations
P_R is also expected to scale with M_H and sigma_H and this is confirmed by our
analysis. We show that all the observed trends can be well reconciled with
expectations in the case of a slight variation of the mean magnetic field
strength in the radio halo volume with M_H. A byproduct correlation between R_H
and sigma_H is also found, and can be further tested by optical studies. In
addition, we find that observationally R_H scales non-linearly with the virial
radius of the host cluster, and this immediately means that the fraction of the
cluster volume which is radio emitting increases with cluster mass and thus
that the non-thermal component in clusters is not self-similar.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 07:59:10 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Cassano",
"R.",
""
],
[
"Brunetti",
"G.",
""
],
[
"Setti",
"G.",
""
],
[
"Govoni",
"F.",
""
],
[
"Dolag",
"K.",
""
]
] |
0704.3491 | Masanori Iye Prof. | M.Iye, M.Tanaka, M.Yanagisawa, N.Ebizuka, K.Ohnishi, C.Hirose,
N.Asami, Y.Komiyama, and H.Furusawa | SuprimeCam Observation of Sporadic Meteors during Perseids 2004 | 14 pages, 13 figures, 5 tables, submitted to PASJ | null | 10.1093/pasj/59.4.841 | null | astro-ph | null | We report the serendipitous findings of 13 faint meteors and 44 artificial
space objects by Subaru SuprimeCam imaging observations during 11-16 August
2004. The meteors, at about 100km altitude, and artificial satellites/debris in
orbit, at 500km altitude or higher, were clearly discriminated by their
apparent defocused image sizes. CCD photometry of the 13 meteors, including 1
Perseid, 1 Aquarid, and 11 sporadic meteors, was performed. We defined a peak
video-rate magnitude by comparing the integrated photon counts from the
brightest portion of the track traversed within 33ms to those from a 0-mag star
during the same time duration. This definition gives magnitudes in the range
4.0< V_{vr} <6.4 and 4.1< I_{vr}<5.9 for these 13 meteors. The corresponding
magnitude for virtual naked-eye observers could be somewhat fainter especially
for the V-band observation, in which the [OI] 5577 line lasting about 1 sec as
an afterglow could contribute to the integrated flux of the present 5-10 min
CCD exposures. Although the spatial resolution is insufficient to resolve the
source size of anything smaller than about 1 m, we developed a new estimate of
the collisionally excited column diameter of these meteors. A diameter as small
as a few mm was derived from their collisionally excited photon rates, meteor
speed, and the volume density of the oxygen atoms at the 100km altitude. The
actual column diameter of the radiating zone, however, could be as large as few
100m because the excited atoms travel that distance before they emit forbidden
lines in 0.7 sec of its average lifetime. Among the 44 artificial space
objects, we confirmed that 17 were cataloged satellites/space debris.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 07:59:24 GMT"
}
] | 2015-05-13T00:00:00 | [
[
"Iye",
"M.",
""
],
[
"Tanaka",
"M.",
""
],
[
"Yanagisawa",
"M.",
""
],
[
"Ebizuka",
"N.",
""
],
[
"Ohnishi",
"K.",
""
],
[
"Hirose",
"C.",
""
],
[
"Asami",
"N.",
""
],
[
"Komiyama",
"Y.",
""
],
[
"Furusawa",
"H.",
""
]
] |
0704.3492 | Roberto Caimmi | R. Caimmi | Holes within galaxies: the egg or the hen? | 60 pages, 6 Figures, improved version with additional computations (2
new figures) related to a generalized hole-dark halo mass relation, appendix
c new, and additional references | New Astron.13:261-284,2008 | 10.1016/j.newast.2007.10.005 | null | astro-ph | null | Unsustained matter distributions unescapely collapse unless fragmentation and
centrifugal or pressure support take place. Starting from the above evidence,
supermassive compact objects at the centre of large-mass galaxies are conceived
as the end-product of the gravitational collapse of local density maxima around
which overdensities are located. At the beginning of evolution, local density
maxima are idealized as homogeneous peaks, while the surrounding envelopes are
described by a power-law density profile. The dependence of the density profile
on a second parameter, chosen to be the ratio between peak and total mass, is
analysed. Overdensity evolution is discussed in the context of quintessence
cosmological models and further investigation is devoted to a special case with
the aim to describe the central collapse. An empirical relation between hole
and dark halo mass is translated into a dependence of the fractional hole mass
on the overdensity mass. Computations are performed up to the end of central
collapse, and density profiles of related configurations are determined
together with additional parameters. The central collapse is completed in early
times, no longer than a few hundredths of Gyr, which implies hole formation
when proto-haloes, proto-bulges, and proto-disks are still expanding or
contracting. No appreciable change in evolution is found with regard to
different mean peak heights related to equal masses. On the other hand, it is
recognized that homogeneous peaks collapse ``faster'' with respect to
surroundings envelopes, in low-mass than in large-mass overdensities. In
conclusion, it is inferred that gravitational collapse of homogeneous peaks
within overdensities may be a viable mechanism for hole generation.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 08:02:53 GMT"
},
{
"version": "v2",
"created": "Tue, 21 Aug 2007 08:32:47 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Caimmi",
"R.",
""
]
] |
0704.3493 | Lei Liu | Lei Liu, Gang Bao, Wei-Tou Ni, D N A Shaul | Simulation of ASTROD I test mass charging due to solar energetic
particles | 10 pages,8 figures, COSPAR2006 H0.1-1, submitted | null | null | null | astro-ph | null | As ASTROD I travels through space, its test mass will accrue charge due to
galactic cosmic-rays and solar energetic particles incident on the spacecraft.
This test mass charge will result in Coulomb forces between the test mass and
the surrounding electrodes. In earlier work using the GEANT4 toolkit, we
predicted a net charging rate of nearly 9.0 +e/s from cosmic-ray protons
between 0.1 and 1000 GeV at solar maximum, and rising to 26.5 +e/s at solar
minimum. Here we use GEANT4 to simulate the charging process due to solar
energetic particle events and to estimate the magnitude of acceleration noise
due to this charging. The predicted charging rates range from 2840 to 64300
+e/s, at peak intensity, for the 4 largest SEP events in September and October
1989. For the 2 larger events, the acceleration disturbances due to charging
exceeds the ASTROD I acceleration noise budget requirement. Continuous
discharge should be considered for suppressing this charging noise. The
acceleration noise during the 2 small events is well below the design target,
although during these events, the net charging rate will be dominated by these
solar fluxes.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 08:07:55 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Liu",
"Lei",
""
],
[
"Bao",
"Gang",
""
],
[
"Ni",
"Wei-Tou",
""
],
[
"Shaul",
"D N A",
""
]
] |
0704.3494 | Victor Ginzburg | Michael Finkelberg and Victor Ginzburg | Cherednik algebras for algebraic curves | final version | null | null | null | math.RT math.QA | null | For any smooth algebraic curve C, Pavel Etingof introduced a `global'
Cherednik algebra as a natural deformation of the cross product of the algebra
of differential operators on C^n and the symmetric group. We provide a
construction of the global Cherednik algebra in terms of quantumn Hamiltonian
reduction. We study a category of character D-modules on a representation
scheme associated to C and define a Hamiltonian reduction functor from that
category to category O for the global Cherednik algebra.
In the special case where the curve C is the multiplicative group, the global
Cherednik algebra reduces to the trigonometric Cherednik algebra of type A, and
our character D-modules become holonomic D-modules on GL_n \times C^n. The
corresponding perverse sheaves are reminiscent of (and include as special
cases) Lusztig's character sheaves.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 08:10:04 GMT"
},
{
"version": "v2",
"created": "Tue, 28 Aug 2007 17:43:58 GMT"
},
{
"version": "v3",
"created": "Wed, 16 Apr 2008 16:48:05 GMT"
}
] | 2008-04-16T00:00:00 | [
[
"Finkelberg",
"Michael",
""
],
[
"Ginzburg",
"Victor",
""
]
] |
0704.3495 | Ting-Wai Chiu | TWQCD Collaboration: Ting-Wai Chiu, Tung-Han Hsieh | Bs and Bc mesons in lattice QCD with exact chiral symmetry | 7 pages, an update of the published version in the Proceedings of
Lattice 2006, Tucson, Arizona, July 23-28, 2006 | PoS LAT2006:180,2007 | null | NTUTH-07-505B | hep-lat hep-ph | null | We determine the masses and decay constants of the pseudoscalar mesons Bs and
Bc, and also the masses of the vector mesons Bs^* and Bc^*, in quenched lattice
QCD with exact chiral symmetry. For 100 gauge configurations generated with
single-plaquette action at beta = 7.2 on the 32^3 x 60 lattice, we compute
point-to-point quark propagators for 33 quark masses in the range [0.01, 0.85],
and measure the time-correlation functions of pseudoscalar and vector mesons.
The inverse lattice spacing and the charm quark bare mass are determined using
the mass and decay constant of eta_c(2980). The bare masses of s and b quarks
are chosen such that the masses of the corresponding vector mesons are in good
agreement with phi(1020), and Upsilon(9460) respectively. Our results are:
m_{Bs} = 5385(27)(17) MeV, f_{Bs} = 253(8)(7) MeV, m_{Bc} = 6278(6)(4) MeV,
f_{Bc} = 489(4)(3) MeV, m_{Bs^*} = 5424(28)(19) MeV, and m_{Bc^*} = 6315(6)(5)
MeV.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 08:19:37 GMT"
},
{
"version": "v2",
"created": "Sun, 29 Apr 2007 06:23:33 GMT"
}
] | 2011-02-16T00:00:00 | [
[
"TWQCD Collaboration",
"",
""
],
[
"Chiu",
"Ting-Wai",
""
],
[
"Hsieh",
"Tung-Han",
""
]
] |
0704.3496 | Frank Gurski | Frank Gurski | Polynomial algorithms for protein similarity search for restricted mRNA
structures | 10 Pages | null | null | null | cs.DS cs.CC | null | In this paper we consider the problem of computing an mRNA sequence of
maximal similarity for a given mRNA of secondary structure constraints,
introduced by Backofen et al. in [BNS02] denoted as the MRSO problem. The
problem is known to be NP-complete for planar associated implied structure
graphs of vertex degree at most 3. In [BFHV05] a first polynomial dynamic
programming algorithms for MRSO on implied structure graphs with maximum vertex
degree 3 of bounded cut-width is shown. We give a simple but more general
polynomial dynamic programming solution for the MRSO problem for associated
implied structure graphs of bounded clique-width. Our result implies that MRSO
is polynomial for graphs of bounded tree-width, co-graphs, $P_4$-sparse graphs,
and distance hereditary graphs. Further we conclude that the problem of
comparing two solutions for MRSO is hard for the class of problems which can be
solved in polynomial time with a number of parallel queries to an oracle in NP.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 08:30:14 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Gurski",
"Frank",
""
]
] |
0704.3497 | Andrzej Opanowicz Dr | A. Opanowicz | Analysis of thermally stimulated luminescence and conductivity without
quasiequilibrium approximation | null | null | 10.1088/0022-3727/40/16/034 | null | nlin.SI | null | Thermally stimulated luminescence (TSL) and conductivity (TSC) are considered
using the classical insulator model that assumes one kind of the active trap,
one kind of inactive deep trap, and one kind of the recombination center.
Kinetic equations describing the model are solved numerically without and with
the use of the quasiequilibrium (QE) approximation. The QE state parameter qI,,
the relative recombination probability g, and a new parameter called
quasi-stationary (QS) state parameter q*=qIg are used for the analysis of the
TSL and TSC. The TSL and TSC curves and the temperature dependences of qI, q*,
g, the recombination lifetime, and the occupancies of active traps and
recombination centers are numerically calculated for five sets of kinetic
parameters and different heating rates. These calculation results show that:
(1) the upper limit of the heating rate for presence of the QS state appears at
higher heating rate than that for the QE state when the retrapping process is
present, and (2) the TSL (TSC) curves in the QS state have the properties
similar to those for the TSL (TSC) curves in the QE state. Approximate formulas
for calculation of the parameters qI and q* in the initial range of the TSL and
TSC curves are derived and used in the heating-rate methods, proposed in this
work, for determination of those parameters from the calculated TSL curves.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 15:19:45 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Opanowicz",
"A.",
""
]
] |
0704.3498 | Alexander E. Dorokhov | Alexander E. Dorokhov, Mikhail A. Ivanov | Rare decay pi0 -> e+e-: theory confronts KTeV data | 7 pages, 1 figure | Phys.Rev.D75:114007,2007 | 10.1103/PhysRevD.75.114007 | null | hep-ph hep-ex | null | Within the dispersive approach to the amplitude of the rare decay pi0 -> e+e-
the nontrivial dynamics is contained only in the subtraction constant. We
express this constant, in the leading order in (m_e/\Lambda)^2 perturbative
series, in terms of the inverse moment of the pion transition form factor given
in symmetric kinematics. By using the CELLO and CLEO data on the pion
transition form factor given in asymmetric kinematics the lower bound on the
decay branching ratio is found. The restrictions following from QCD allow us to
make a quantitative prediction for the branching B(pi0 -> e+e-) =(6.2\pm
0.1)*10^{-8} which is 3\sigma below the recent KTeV measurement. We confirm our
prediction by using the quark models and phenomenological approaches based on
the vector meson dominance. The decays \eta -> l^+l^- are also discussed.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 09:09:35 GMT"
},
{
"version": "v2",
"created": "Fri, 25 May 2007 12:43:02 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Dorokhov",
"Alexander E.",
""
],
[
"Ivanov",
"Mikhail A.",
""
]
] |
0704.3499 | Francois Labourie | Thomas Delzant (IRMA), Olivier Guichard (LM-Orsay), Fran\c{c}ois
Labourie (LM-Orsay), Shahar Mozes | Well displacing representations and orbit maps | null | null | null | null | math.GT math.GR | null | We discuss in this article a property of action of groups by isometries
called "well displacing". An action is said to be well displacing, if the
displacement function is equivalent to the the displacement function for the
action on the Cayley graph. We relate this property with the fact that orbit
maps are quasi-isometric embeddings. We first describe countrexamples that
shows this two notions are unrelated in general. On the other hand we explain
that for a certain class of groups -- in particular hyperbolic groups -- these
two properties are equivalent. In the course of our discussion, we introduce an
intrinsic property of the group -- that we called the U-property -- which says
quantitatively how the norm an element is controlled by the translation length
of finitely many related conjugacy classes. This property play a central role
in our discussion.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 09:01:22 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Delzant",
"Thomas",
"",
"IRMA"
],
[
"Guichard",
"Olivier",
"",
"LM-Orsay"
],
[
"Labourie",
"François",
"",
"LM-Orsay"
],
[
"Mozes",
"Shahar",
""
]
] |
0704.3500 | Jerome Darmont | Zhen He, J\'er\^ome Darmont (ERIC) | Une plate-forme dynamique pour l'\'evaluation des performances des bases
de donn\'ees \`a objets | 20 pages | 19\`emes Journ\'ees de Bases de Donn\'ees Avanc\'ees (BDA 03),
Lyon (20/10/2003) 423-442 | null | null | cs.DB | null | In object-oriented or object-relational databases such as multimedia
databases or most XML databases, access patterns are not static, i.e.,
applications do not always access the same objects in the same order
repeatedly. However, this has been the way these databases and associated
optimisation techniques such as clustering have been evaluated up to now. This
paper opens up research regarding this issue by proposing a dynamic object
evaluation framework (DOEF). DOEF accomplishes access pattern change by
defining configurable styles of change. It is a preliminary prototype that has
been designed to be open and fully extensible. Though originally designed for
the object-oriented model, it can also be used within the object-relational
model with few adaptations. Furthermore, new access pattern change models can
be added too. To illustrate the capabilities of DOEF, we conducted two
different sets of experiments. In the first set of experiments, we used DOEF to
compare the performances of four state of the art dynamic clustering
algorithms. The results show that DOEF is effective at determining the
adaptability of each dynamic clustering algorithm to changes in access pattern.
They also led us to conclude that dynamic clustering algorithms can cope with
moderate levels of access pattern change, but that performance rapidly degrades
to be worse than no clustering when vigorous styles of access pattern change
are applied. In the second set of experiments, we used DOEF to compare the
performance of two different object stores: Platypus and SHORE. The use of DOEF
exposed the poor swapping performance of Platypus.
| [
{
"version": "v1",
"created": "Thu, 26 Apr 2007 09:10:41 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"He",
"Zhen",
"",
"ERIC"
],
[
"Darmont",
"Jérôme",
"",
"ERIC"
]
] |
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