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list | update_date
timestamp[s] | authors_parsed
sequence |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
0707.0630 | Oliver Burmeister | A. Bunkowski, O. Burmeister, K. Danzmann, R. Schnabel | Demonstration of 3-port grating phase relations | null | Optics Letters 31, 2384 (2006) | 10.1364/OL.31.002384 | null | physics.optics | null | We experimentally demonstrate the phase relations of 3-port gratings by
investigating 3-port coupled Fabry-Perot cavities. Two different gratings which
have the same 1st order diffraction efficiency but differ substantially in
their 2nd order diffraction efficiency have been designed and manufactured.
Using the gratings as couplers to Fabry-Perot cavities we could validate the
results of an earlier theoretical description of the phases at a three port
grating.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 14:56:29 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Bunkowski",
"A.",
""
],
[
"Burmeister",
"O.",
""
],
[
"Danzmann",
"K.",
""
],
[
"Schnabel",
"R.",
""
]
] |
0707.0631 | Igor Tralle | I. Tralle, W. Pasko | On the environmental decoherence and spin interference in mesoscopic
loop structures | null | Physica E: Low-dimensional systems and nanostructures,
vol.19,pp.336-348 (2003) | 10.1016/S1386-9477(03)00378-3 | null | cond-mat.mes-hall cond-mat.other | null | Mechanisms of 'environmental decoherence' such as surface scattering,
Elliot-Yafet process and precession mechanisms, as well as their influence on
the spin phase relaxation are considered and compared. It is shown that the
'spin ballistic' regime is possible, when the phase relaxation length for the
spin part of the wave function (WF)is much greater than the phase relaxation
length for the 'orbital part'. In the presence of an additional magnetic field,
the spin part of the electron's WF acquires a phase shift due to additional
spin precession about that field. If the structure length is chosen to be
greater than the phase relaxation length for the 'orbital part' and less than
the phase relaxation length for the spin part of WF, it is possible to 'wash
out' the quantum interference related to the phase coherence of the 'orbital
part' of the WF, retaining at the same time that related to the phase coherence
of the spin part and, hence, to reveal corresponding conductance oscillations.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 15:00:27 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Tralle",
"I.",
""
],
[
"Pasko",
"W.",
""
]
] |
0707.0632 | Verena Kleinhaus | Verena Kleinhaus, Michael Buballa, Dominik Nickel, Micaela Oertel | Pseudoscalar Goldstone bosons in the color-flavor locked phase at
moderate densities | 18 pages, 12 figures | Phys.Rev.D76:074024,2007 | 10.1103/PhysRevD.76.074024 | null | hep-ph nucl-th | null | The properties of the pseudoscalar Goldstone bosons in the color-flavor
locked phase at moderate densities are studied within a model of the
Nambu--Jona-Lasinio type. The Goldstone bosons are constructed explicitly by
solving the Bethe-Salpeter equation for quark-quark scattering in random phase
approximation. Main focus of our investigations are (i) the weak decay constant
in the chiral limit, (ii) the masses of the flavored (pseudo-) Goldstone bosons
for non-zero but equal quark masses, (iii) their masses and effective chemical
potentials for non-equal quark masses, and (iv) the onset of kaon condensation.
We compare our results with the predictions of the low-energy effective field
theory. The deviations from results obtained in the weak-coupling limit are
discussed in detail.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 17:02:12 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Kleinhaus",
"Verena",
""
],
[
"Buballa",
"Michael",
""
],
[
"Nickel",
"Dominik",
""
],
[
"Oertel",
"Micaela",
""
]
] |
0707.0633 | Michel Tytgat | Thomas Hambye and Michel H.G. Tytgat | Electroweak Symmetry Breaking induced by Dark Matter | 4 pages, no figure, one table | Phys.Lett.B659:651-655,2008 | 10.1016/j.physletb.2007.11.069 | ULB-TH/07-26 | hep-ph | null | The mechanism behind Electroweak Symmetry Breaking (EWSB) and the nature of
dark matter (DM) are currently among the most important issues in high energy
physics. Since a natural dark matter candidate is a weakly interacting massive
particle or WIMP, with mass around the electroweak scale, it is clearly of
interest to investigate the possibility that DM and EWSB are closely related.
In the context of a very simple extension of the Standard Model, the Inert
Doublet Model, we show that dark matter could play a crucial role in the
breaking of the electroweak symmetry. In this model, dark matter is the
lightest component of an inert scalar doublet. The coupling of the latter with
the Standard Model Higgs doublet breaks the electroweak symmetry at one-loop,
"a la Coleman-Weinberg". The abundance of dark matter, the breaking of the
electroweak symmetry and the constraints from electroweak precision
measurements can all be accommodated by imposing an (exact or approximate)
custodial symmetry.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 15:06:23 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Hambye",
"Thomas",
""
],
[
"Tytgat",
"Michel H. G.",
""
]
] |
0707.0634 | Antoaneta Antonova | A. Antonova, J.G. Doyle, G. Hallinan, A. Golden, C. Koen | Sporadic Long-term Variability in Radio Activity from a Brown Dwarf | 7 pages, 2 figures, 1 table, accepted for publication in A&A Letters | null | 10.1051/0004-6361:20077231 | null | astro-ph | null | Radio activity has been observed in a large variety of stellar objects,
including in the last few years, ultra-cool dwarfs. To explore the extent of
long-term radio activity in ultra-cool dwarfs, we use data taken over an
extended period of 9 hr from the Very Large Array of the source 2MASS
J05233822-1403022 in September 2006, plus data taken in 2004. The observation
taken in September 2006 failed to detect any radio activity at 8.46 GHz. A
closer inspection of earlier data reveals that the source varied from a null
detection on 3 May 2004, to $\approx$95 $\mu$Jy on 17 May 2004, to 230 $\mu$Jy
on 18 June 2004. The lack of detection in September 2006 suggests at least a
factor of ten flux variability at 8.46 GHz. Three short photometric runs did
not reveal any optical variability. In addition to the observed pulsing nature
of the radio flux from another ultra-cool source, the present observations
suggests that ultra-cool dwarfs may not just be pulsing but can also display
long-term sporadic variability in their levels of quiescent radio emission. The
lack of optical photometric variability suggests an absence of large-scale
spots at the time of the latest VLA observations, although small very high
latitude spots combined with a low inclination could cause very low amplitude
rotational modulation which may not be measurable. We discuss this large
variability in the radio emission within the context of both gyrosynchrotron
emission and the electron-cyclotron maser, favoring the latter mechanism.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 15:06:56 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Antonova",
"A.",
""
],
[
"Doyle",
"J. G.",
""
],
[
"Hallinan",
"G.",
""
],
[
"Golden",
"A.",
""
],
[
"Koen",
"C.",
""
]
] |
0707.0635 | E. Canessa | E. Canessa | Possible Connection between Probability, Spacetime Geometry and Quantum
Mechanics | in press | PhysicaA385:185-190,2007 | 10.1016/j.physa.2007.06.006 | null | gr-qc cond-mat.other quant-ph | null | Following our discussion [Physica A, 375 (2007) 123] to associate an
analogous probabilistic description with spacetime geometry in the
Schwarzschild metric from the macro- to the micro-domain, we argue that there
is a possible connection among normalized probabilities, spacetime geometry (in
the form of Schwarzschild radii) and quantum mechanics (in the form of complex
wave functions). We show how this association along different (n)-nested
surfaces --representing curve space due to an inhomogeneous density of matter--
preserves the postulates of quantum mechanics at different geometrical scales.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 15:26:17 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Canessa",
"E.",
""
]
] |
0707.0636 | Luca Silvestrini | UTfit Collaboration: M. Bona, M. Ciuchini, E. Franco, V. Lubicz, G.
Martinelli, F. Parodi, M. Pierini, P. Roudeau, C. Schiavi, L. Silvestrini, V.
Sordini, A. Stocchi, V. Vagnoni | Model-independent constraints on Delta F=2 operators and the scale of
New Physics | 32 pages, 11 figures, 6 tables. v2: error in the implementation of D0
untagged Bs->J/Psi phi correlation matrix corrected. Improved presentation of
the results and discussion of ambiguities in untagged Bs->J/Psi phi. Results
for NP in Bs oscillations changed. Final version to appear in JHEP | JHEP 0803:049,2008 | 10.1088/1126-6708/2008/03/049 | null | hep-ph | null | We update the constraints on new-physics contributions to Delta F=2 processes
from the generalized unitarity triangle analysis, including the most recent
experimental developments. Based on these constraints, we derive upper bounds
on the coefficients of the most general Delta F=2 effective Hamiltonian. These
upper bounds can be translated into lower bounds on the scale of new physics
that contributes to these low-energy effective interactions. We point out that,
due to the enhancement in the renormalization group evolution and in the matrix
elements, the coefficients of non-standard operators are much more constrained
than the coefficient of the operator present in the Standard Model. Therefore,
the scale of new physics in models that generate new Delta F=2 operators, such
as next-to-minimal flavour violation, has to be much higher than the scale of
minimal flavour violation, and it most probably lies beyond the reach of direct
searches at the LHC.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 15:09:14 GMT"
},
{
"version": "v2",
"created": "Fri, 29 Feb 2008 10:36:23 GMT"
}
] | 2011-03-23T00:00:00 | [
[
"UTfit Collaboration",
"",
""
],
[
"Bona",
"M.",
""
],
[
"Ciuchini",
"M.",
""
],
[
"Franco",
"E.",
""
],
[
"Lubicz",
"V.",
""
],
[
"Martinelli",
"G.",
""
],
[
"Parodi",
"F.",
""
],
[
"Pierini",
"M.",
""
],
[
"Roudeau",
"P.",
""
],
[
"Schiavi",
"C.",
""
],
[
"Silvestrini",
"L.",
""
],
[
"Sordini",
"V.",
""
],
[
"Stocchi",
"A.",
""
],
[
"Vagnoni",
"V.",
""
]
] |
0707.0637 | Antti Manninen | Antti Manninen, Anu Karkkainen, Nadine Pesonen, Aarne Oja, and Heikki
Seppa | Microelectromechanical components in electrical metrology | null | A. Manninen, A. Karkkainen, N. Pesonen, A. Oja, and H. Seppa,
Applications des MEMS a la metrologie electrique. Techniques de l Ingenieur,
traite Mesures et Controle, juin 2007. R 1002, 12 pages (in French) | null | null | physics.ins-det | null | Microelectromechanical systems (MEMS) can offer a competitive alternative for
conventional technology in electrical precision measurements. This article
summarises recent work in development of MEMS solutions for electrical
metrology. MEMS-based voltage references, RMS-to-DC converters, high frequency
power sensors, and reference oscillators are discussed. The main principle of
operation of the components is the balance between electrical forces and
mechanical spring forces in micromachined silicon structures. In RMS sensors
and RMS-to-DC converters, the quadratic voltage dependence of the force between
plates of a moving-plate capacitor is utilised, and the operation of the MEMS
voltage reference is based on the pull-in phenomenon of a moving-plate
capacitor. Advantages of MEMS devices compared to more conventional solutions
include small size, low power consumption, low price in mass production, and
stability. The drift caused by electrostatic charging effects has turned out to
be a major problem. This problem has not yet been solved in DC applications,
but it can be circumvented by using AC actuation instead of DC and by
compensating the internal DC voltages of the component. In this way, an AC
voltage reference with relative drift rate below 2 ppm during a three-week test
period has been constructed. Even better stability has been demonstrated with a
MEMS-based reference oscillator: no changes in resonance frequency were
observed at relative uncertainty level of about 0.01 ppm in a measurement which
was continued for more than a month. MEMS components have also been developed
for measuring RF and microwave power up to frequencies of about 40 GHz. Unlike
conventional high frequency power sensors, which measure the absorbed power,
the MEMS device measures the power that is transmitted through the sensor.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 15:18:29 GMT"
}
] | 2007-07-05T00:00:00 | [
[
"Manninen",
"Antti",
""
],
[
"Karkkainen",
"Anu",
""
],
[
"Pesonen",
"Nadine",
""
],
[
"Oja",
"Aarne",
""
],
[
"Seppa",
"Heikki",
""
]
] |
0707.0638 | Valentina Cannelli Dr | V. Cannelli, D. Melini, P. De Michelis, A. Piersanti, F. Florindo | Core-mantle boundary deformations and J2 variations resulting from the
2004 Sumatra earthquake | 14 pages, 8 figures, 1 table. It will appear in Geophysical Journal
International | null | 10.1111/j.1365-246X.2007.03443.x | null | physics.geo-ph | null | The deformation at the core-mantle boundary produced by the 2004 Sumatra
earthquake is investigated by means of a semi-analytic theoretical model of
global coseismic and postseismic deformation, predicting a millimetric
coseismic perturbation over a large portion of the core-mantle boundary.
Spectral features of such deformations are analysed and discussed. The
time-dependent postseismic evolution of the elliptical part of the gravity
field (J2) is also computed for different asthenosphere viscosity models. Our
results show that, for asthenospheric viscosities smaller than 10^18 Pa s, the
postseismic J2 variation in the next years is expected to leave a detectable
signal in geodetic observations.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 15:26:28 GMT"
}
] | 2007-07-05T00:00:00 | [
[
"Cannelli",
"V.",
""
],
[
"Melini",
"D.",
""
],
[
"De Michelis",
"P.",
""
],
[
"Piersanti",
"A.",
""
],
[
"Florindo",
"F.",
""
]
] |
0707.0639 | Francesco Cordero | F. Cordero | Hopping and clustering of oxygen vacancies in SrTiO3 by anelastic
relaxation | 4 pages, 4 figures, submitted to Phys. Rev. Lett | Phys. Rev. B 76, 172106 (2007) | 10.1103/PhysRevB.76.172106 | null | cond-mat.mtrl-sci cond-mat.stat-mech | null | The complex elastic compliance s11(w,T) of SrTiO3-d has been measured as a
function of the O deficiency d < 0.01. The two main relaxation peaks in the
absorption are identified with hopping of isolated O vacancies over a barrier
of 0.60 eV and reorientation of pairs of vacancies involving a barrier of 1 eV.
The pair binding energy is ~0.2 eV and indications for additional clustering,
possibly into chains, is found already at d ~0.004. The anistropic component of
the elastic dipole of an O vacancy is Deltalambda = 0.026.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 15:29:07 GMT"
}
] | 2010-07-23T00:00:00 | [
[
"Cordero",
"F.",
""
]
] |
0707.0640 | Carlos Rascon | A.O. Parry, C. Rascon, N.R. Bernardino, J.M. Romero-Enrique | Derivation of a Non-Local Interfacial Hamiltonian for Short-Ranged
Wetting II: General Diagrammatic Structure | (14 pages, 2 figures) Submitted J. Phys. Condens. Matter | null | 10.1088/0953-8984/19/41/416105 | null | cond-mat.stat-mech cond-mat.soft | null | In our first paper, we showed how a non-local effective Hamiltionian for
short-ranged wetting may be derived from an underlying Landau-Ginzburg-Wilson
model. Here, we combine the Green's function method with standard perturbation
theory to determine the general diagrammatic form of the binding potential
functional beyond the double-parabola approximation for the
Landau-Ginzburg-Wilson bulk potential. The main influence of cubic and quartic
interactions is simply to alter the coefficients of the double parabola-like
zig-zag diagrams and also to introduce curvature and tube-interaction
corrections (also represented diagrammatically), which are of minor importance.
Non-locality generates effective long-ranged many-body interfacial interactions
due to the reflection of tube-like fluctuations from the wall. Alternative wall
boundary conditions (with a surface field and enhancement) and the diagrammatic
description of tricritical wetting are also discussed.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 15:30:51 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Parry",
"A. O.",
""
],
[
"Rascon",
"C.",
""
],
[
"Bernardino",
"N. R.",
""
],
[
"Romero-Enrique",
"J. M.",
""
]
] |
0707.0641 | Sebastien Verel | S\'ebastien Verel (I3S), Philippe Collard (I3S), Manuel Clergue (I3S) | Where are Bottlenecks in NK Fitness Landscapes? | null | Evolutionary Computation, 2003. CEC'03 (08/12/2003) 273--280 | 10.1109/CEC.2003.1299585 | null | cs.NE | null | Usually the offspring-parent fitness correlation is used to visualize and
analyze some caracteristics of fitness landscapes such as evolvability. In this
paper, we introduce a more general representation of this correlation, the
Fitness Cloud (FC). We use the bottleneck metaphor to emphasise fitness levels
in landscape that cause local search process to slow down. For a local search
heuristic such as hill-climbing or simulated annealing, FC allows to visualize
bottleneck and neutrality of landscapes. To confirm the relevance of the FC
representation we show where the bottlenecks are in the well-know NK fitness
landscape and also how to use neutrality information from the FC to combine
some neutral operator with local search heuristic.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 15:30:54 GMT"
}
] | 2007-07-05T00:00:00 | [
[
"Verel",
"Sébastien",
"",
"I3S"
],
[
"Collard",
"Philippe",
"",
"I3S"
],
[
"Clergue",
"Manuel",
"",
"I3S"
]
] |
0707.0642 | Yannick Ponty | Julien Baerenzung (OCA), Helene Politano (OCA), Yannick Ponty (OCA),
Annick Pouquet (NCAR) | Spectral Modeling of Turbulent Flows and the Role of Helicity | null | null | 10.1103/PhysRevE.77.046303 | null | physics.flu-dyn physics.class-ph | null | We present a new version of a dynamical spectral model for Large Eddy
Simulation based on the Eddy Damped Quasi Normal Markovian approximation
\cite{sao,chollet_lesieur}. Three distinct modifications are implemented and
tested. On the one hand, whereas in current approaches, a Kolmogorov-like
energy spectrum is usually assumed in order to evaluate the nonlocal transfer,
in our method the energy spectrum of the subgrid scales adapts itself
dynamically to the large-scale resolved spectrum; this first modification
allows in particular for a better treatment of transient phases and
instabilities, as shown on one specific example. Moreover, the model takes into
account the phase relationships of the small-scales, embodied for example in
strong localized structures such as vortex filaments. To that effect, phase
information is implemented in the treatment of the so-called eddy noise in the
closure model. Finally, we also consider the role that helical small scales may
play in the evaluation of the transfer of energy and helicity, the two
invariants of the primitive equations in the inviscid case; this leads as well
to intrinsic variations in the development of helicity spectra. Therefore, our
model allows for simulations of flows for a variety of circumstances and a
priori at any given Reynolds number. Comparisons with Direct Numerical
Simulations of the three-dimensional Navier-Stokes equation are performed on
fluids driven by an ABC (Beltrami) flow which is a prototype of fully helical
flows. Good agreements are obtained for physical and spectral behavior of the
large scales.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 15:34:21 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Baerenzung",
"Julien",
"",
"OCA"
],
[
"Politano",
"Helene",
"",
"OCA"
],
[
"Ponty",
"Yannick",
"",
"OCA"
],
[
"Pouquet",
"Annick",
"",
"NCAR"
]
] |
0707.0643 | Sebastien Verel | S\'ebastien Verel (I3S), Philippe Collard (I3S), Manuel Clergue (I3S) | Scuba Search : when selection meets innovation | null | Evolutionary Computation, 2004. CEC2004 (23/06/2004) 924 - 931 | 10.1109/CEC.2004.1330960 | null | cs.NE | null | We proposed a new search heuristic using the scuba diving metaphor. This
approach is based on the concept of evolvability and tends to exploit
neutrality in fitness landscape. Despite the fact that natural evolution does
not directly select for evolvability, the basic idea behind the scuba search
heuristic is to explicitly push the evolvability to increase. The search
process switches between two phases: Conquest-of-the-Waters and
Invasion-of-the-Land. A comparative study of the new algorithm and standard
local search heuristics on the NKq-landscapes has shown advantage and limit of
the scuba search. To enlighten qualitative differences between neutral search
processes, the space is changed into a connected graph to visualize the
pathways that the search is likely to follow.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 15:36:35 GMT"
}
] | 2007-07-05T00:00:00 | [
[
"Verel",
"Sébastien",
"",
"I3S"
],
[
"Collard",
"Philippe",
"",
"I3S"
],
[
"Clergue",
"Manuel",
"",
"I3S"
]
] |
0707.0644 | Ali Akhavi | Ali Akhavi (GREYC), C\'eline Moreira (GREYC) | Another view of the Gaussian algorithm | null | Proceedings of Latin'04 (04/2004) 474--487 | null | null | cs.DS cs.DM | null | We introduce here a rewrite system in the group of unimodular matrices,
\emph{i.e.}, matrices with integer entries and with determinant equal to $\pm
1$. We use this rewrite system to precisely characterize the mechanism of the
Gaussian algorithm, that finds shortest vectors in a two--dimensional lattice
given by any basis. Putting together the algorithmic of lattice reduction and
the rewrite system theory, we propose a new worst--case analysis of the
Gaussian algorithm. There is already an optimal worst--case bound for some
variant of the Gaussian algorithm due to Vall\'ee \cite {ValGaussRevisit}. She
used essentially geometric considerations. Our analysis generalizes her result
to the case of the usual Gaussian algorithm. An interesting point in our work
is its possible (but not easy) generalization to the same problem in higher
dimensions, in order to exhibit a tight upper-bound for the number of
iterations of LLL--like reduction algorithms in the worst case. Moreover, our
method seems to work for analyzing other families of algorithms. As an
illustration, the analysis of sorting algorithms are briefly developed in the
last section of the paper.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 15:37:15 GMT"
}
] | 2007-07-05T00:00:00 | [
[
"Akhavi",
"Ali",
"",
"GREYC"
],
[
"Moreira",
"Céline",
"",
"GREYC"
]
] |
0707.0645 | Christophe Denoual | L. Pillon, C. Denoual, Y.-P. Pellegrini | Equation of motion for dislocations with inertial effects | 6 pages, 4 figures, LaTeX | Phys. Rev. B 76, 224105 (2007) | 10.1103/PhysRevB.76.224105 | null | cond-mat.mtrl-sci | null | An approximate equation of motion is proposed for screw and edge
dislocations, which accounts for retardation and for relativistic effects in
the subsonic range. Good quantitative agreement is found, in accelerated or in
decelerated regimes, with numerical results of a more fundamental nature.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 15:39:20 GMT"
}
] | 2008-04-17T00:00:00 | [
[
"Pillon",
"L.",
""
],
[
"Denoual",
"C.",
""
],
[
"Pellegrini",
"Y. -P.",
""
]
] |
0707.0646 | Cacciatori Sergio | Sergio Cacciatori, Francesco Dalla Piazza | Two loop superstring amplitudes and S_6 representations | 10 pages, comments and reference added in the conclusions | Lett.Math.Phys.83:127-138,2008 | 10.1007/s11005-007-0213-8 | null | hep-th | null | In this paper we describe how representation theory of groups can be used to
shorten the derivation of two loop partition functions in string theory, giving
an intrinsic description of modular forms appearing in the results of D'Hoker
and Phong [1]. Our method has the advantage of using only algebraic properties
of modular functions and it can be extended to any genus g.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 15:44:59 GMT"
},
{
"version": "v2",
"created": "Fri, 13 Jul 2007 13:33:54 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Cacciatori",
"Sergio",
""
],
[
"Piazza",
"Francesco Dalla",
""
]
] |
0707.0647 | Tao Xu | Tao Xu, Hai-Qiang Zhang, Ya-Xing Zhang, Juan Li and Bo Tian | Two types of generalized integrable decompositions and new solitary-wave
solutions for the modified Kadomtsev-Petviashvili equation with symbolic
computation | 23 pages | null | 10.1063/1.2825247 | null | math-ph math.MP | null | The modified Kadomtsev-Petviashvili (mKP) equation is shown in this paper to
be decomposable into the first two soliton equations of the 2N-coupled
Chen-Lee-Liu and Kaup-Newell hierarchies by respectively nonlinearizing two
sets of symmetry Lax pairs. In these two cases, the decomposed
(1+1)-dimensional nonlinear systems both have a couple of different Lax
representations, which means that there are two linear systems associated with
the mKP equation under the same constraint between the potential and
eigenfunctions. For each Lax representation of the decomposed (1+1)-dimensional
nonlinear systems, the corresponding Darboux transformation is further
constructed such that a series of explicit solutions of the mKP equation can be
recursively generated with the assistance of symbolic computation. In
illustration, four new families of solitary-wave solutions are presented and
the relevant stability is analyzed.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 15:50:07 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Xu",
"Tao",
""
],
[
"Zhang",
"Hai-Qiang",
""
],
[
"Zhang",
"Ya-Xing",
""
],
[
"Li",
"Juan",
""
],
[
"Tian",
"Bo",
""
]
] |
0707.0648 | Viswanath Nagarajan | Anupam Gupta, MohammadTaghi Hajiaghayi, Viswanath Nagarajan, R. Ravi | Dial a Ride from k-forest | Preliminary version in Proc. European Symposium on Algorithms, 2007 | null | null | null | cs.DS | null | The k-forest problem is a common generalization of both the k-MST and the
dense-$k$-subgraph problems. Formally, given a metric space on $n$ vertices
$V$, with $m$ demand pairs $\subseteq V \times V$ and a ``target'' $k\le m$,
the goal is to find a minimum cost subgraph that connects at least $k$ demand
pairs. In this paper, we give an $O(\min\{\sqrt{n},\sqrt{k}\})$-approximation
algorithm for $k$-forest, improving on the previous best ratio of
$O(n^{2/3}\log n)$ by Segev & Segev.
We then apply our algorithm for k-forest to obtain approximation algorithms
for several Dial-a-Ride problems. The basic Dial-a-Ride problem is the
following: given an $n$ point metric space with $m$ objects each with its own
source and destination, and a vehicle capable of carrying at most $k$ objects
at any time, find the minimum length tour that uses this vehicle to move each
object from its source to destination. We prove that an $\alpha$-approximation
algorithm for the $k$-forest problem implies an
$O(\alpha\cdot\log^2n)$-approximation algorithm for Dial-a-Ride. Using our
results for $k$-forest, we get an $O(\min\{\sqrt{n},\sqrt{k}\}\cdot\log^2 n)$-
approximation algorithm for Dial-a-Ride. The only previous result known for
Dial-a-Ride was an $O(\sqrt{k}\log n)$-approximation by Charikar &
Raghavachari; our results give a different proof of a similar approximation
guarantee--in fact, when the vehicle capacity $k$ is large, we give a slight
improvement on their results.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 16:08:40 GMT"
}
] | 2007-07-05T00:00:00 | [
[
"Gupta",
"Anupam",
""
],
[
"Hajiaghayi",
"MohammadTaghi",
""
],
[
"Nagarajan",
"Viswanath",
""
],
[
"Ravi",
"R.",
""
]
] |
0707.0649 | Albert Guill\'en i F\`abregas | Albert Guillen i Fabregas and Emanuele Viterbo | Sphere Lower Bound for Rotated Lattice Constellations in Fading Channels | accepted for publication at the IEEE Transactions on Wireless
Communications | null | null | null | cs.IT math.IT | null | We study the error probability performance of rotated lattice constellations
in frequency-flat Nakagami-$m$ block-fading channels. In particular, we use the
sphere lower bound on the underlying infinite lattice as a performance
benchmark. We show that the sphere lower bound has full diversity. We observe
that optimally rotated lattices with largest known minimum product distance
perform very close to the lower bound, while the ensemble of random rotations
is shown to lack diversity and perform far from it.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 15:56:03 GMT"
}
] | 2007-07-13T00:00:00 | [
[
"Fabregas",
"Albert Guillen i",
""
],
[
"Viterbo",
"Emanuele",
""
]
] |
0707.0650 | Alexander Bednyakov | A.V. Bednyakov | Running mass of the b-quark in QCD and SUSY QCD | 33 pages, 6 figures, 1 table, typos corrected, added references) | Int.J.Mod.Phys.A22:5245-5277,2007 | 10.1142/S0217751X07038037 | null | hep-ph | null | The running mass of the b-quark defined in DRbar-scheme is one of the
important parameters of SUSY QCD. To find its value it should be related to
some known experimental input. In this paper the b-quark running mass defined
in nonsupersymmetric QCD is chosen for determination of corresponding parameter
in SUSY QCD. The relation between these two quantities is found by considering
five-flavor QCD as an effective theory obtained from its supersymmetric
extension. A numerical analysis of the calculated two-loop relation and its
impact on the MSSM spectrum is discussed. Since for nonsupersymmetric models
MSbar-scheme is more natural than DRbar, we also propose a new procedure that
allows one to calculate relations between MSbar- and DRbar-parameters.
Unphysical epsilon-scalars that give rise to the difference between mentioned
schemes are assumed to be heavy and decoupled in the same way as physical
degrees of freedom. By means of this method it is possible to ``catch two
rabbits'', i.e., decouple heavy particles and turn from DRbar to MSbar, at the
same time. Explicit two-loop example of DRbar -> MSbar transition is given in
the context of QCD. The advantages and disadvantages of the method are briefly
discussed.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 15:57:59 GMT"
},
{
"version": "v2",
"created": "Mon, 11 Feb 2008 09:21:27 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Bednyakov",
"A. V.",
""
]
] |
0707.0651 | Sarzi Marc | M. Sarzi, E. L. Allard, J. H. Knapen, L. M. Mazzuca | Star formation and stellar populations across nuclear rings in galaxies | 15 pages, 10 figures, accepted for publication on MNRAS | null | 10.1111/j.1365-2966.2007.12177.x | null | astro-ph | null | (Abridged) We present a study of the optical spectra of a sample of eight
star-forming nuclear rings and the nuclei of their host galaxies. The spectra
were obtained with the ISIS spectrograph on the William Herschel Telescope and
cover a wide range in wavelength, enabling the measurement of several stellar
absorption features and gas emission lines.
We compared the strength of the absorption lines to a variety of population
synthesis models for the star-formation history in the nuclear rings, including
also the contribution of the older bulge and disc stellar components. We find
that the stars in our sample of nuclear rings have most likely formed over a
prolonged period of time characterised by episodic bursts of star-formation
activity. Constant star formation is firmly ruled out by the data, whereas a
one-off formation event is an unlikely explanation for a common galactic
component such as nuclear rings.
We have used emission-line measurements to constrain the physical conditions
of the ionised gas within the rings. Emission in all nuclear rings originates
from HII-regions with electron densities typical for these kinds of objects,
and that the rings are characterised by values for the gas metallicity ranging
from slightly below to just above solar.
As 20% of nearby spiral galaxies hosts nuclear rings that are currently
forming massive stars, our finding of an episodic star formation history in
nuclear rings implies that a significant population remains to be identified of
young nuclear rings that are not currently in a massive star formation phase.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 15:59:32 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Sarzi",
"M.",
""
],
[
"Allard",
"E. L.",
""
],
[
"Knapen",
"J. H.",
""
],
[
"Mazzuca",
"L. M.",
""
]
] |
0707.0652 | Sebastien Verel | Philippe Collard (I3S), S\'ebastien Verel (I3S), Manuel Clergue (I3S) | How to use the Scuba Diving metaphor to solve problem with neutrality ? | null | ECAI'2004 (27/08/2004) 166-170 | null | null | cs.NE | null | We proposed a new search heuristic using the scuba diving metaphor. This
approach is based on the concept of evolvability and tends to exploit
neutrality which exists in many real-world problems. Despite the fact that
natural evolution does not directly select for evolvability, the basic idea
behind the scuba search heuristic is to explicitly push evolvability to
increase. A comparative study of the scuba algorithm and standard local search
heuristics has shown the advantage and the limitation of the scuba search. In
order to tune neutrality, we use the NKq fitness landscapes and a family of
travelling salesman problems (TSP) where cities are randomly placed on a
lattice and where travel distance between cities is computed with the Manhattan
metric. In this last problem the amount of neutrality varies with the city
concentration on the grid ; assuming the concentration below one, this TSP
reasonably remains a NP-hard problem.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 16:12:17 GMT"
}
] | 2007-07-05T00:00:00 | [
[
"Collard",
"Philippe",
"",
"I3S"
],
[
"Verel",
"Sébastien",
"",
"I3S"
],
[
"Clergue",
"Manuel",
"",
"I3S"
]
] |
0707.0653 | Eric Ragoucy | Luc Frappat (LAPTH), Rafael Nepomechie, Eric Ragoucy (LAPTH) | Complete Bethe Ansatz solution of the open spin-s XXZ chain with general
integrable boundary terms | 23 pages -- Latex2e; misprints in appendix corrected | J.Stat.Mech.0709:P09009,2007 | 10.1088/1742-5468/2007/09/P09009 | null | math-ph hep-th math.MP | null | We consider the open spin-s XXZ quantum spin chain with N sites and general
integrable boundary terms for generic values of the bulk anisotropy parameter,
and for values of the boundary parameters which satisfy a certain constraint.
We derive two sets of Bethe Ansatz equations, and find numerical evidence that
together they give the complete set of $(2s+1)^{N}$ eigenvalues of the transfer
matrix. For the case s=1, we explicitly determine the Hamiltonian, and find an
expression for its eigenvalues in terms of Bethe roots.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 16:14:11 GMT"
},
{
"version": "v2",
"created": "Mon, 9 Jul 2007 12:43:13 GMT"
}
] | 2010-04-08T00:00:00 | [
[
"Frappat",
"Luc",
"",
"LAPTH"
],
[
"Nepomechie",
"Rafael",
"",
"LAPTH"
],
[
"Ragoucy",
"Eric",
"",
"LAPTH"
]
] |
0707.0654 | Osvaldo Chandia | Osvaldo Chandia, Mario Tonin | BRST Anomaly and Superspace Constraints of the Pure Spinor Heterotic
String in a Curved Background | harvmac-big, 18 pages; references added; minor corrections | JHEP 0709:016,2007 | 10.1088/1126-6708/2007/09/016 | DFPD 07/TH/13 | hep-th | null | The pure spinor heterotic string in a generic super Yang-Mills and
supergravity background is considered. We determine the one-loop BRST anomaly
at the cohomological level. We prove that it can be absorbed by consistent
corrections of the classical constraints due to Berkovits and Howe, in
agreement with the Green-Schwarz cancelation mechanism.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 16:14:25 GMT"
},
{
"version": "v2",
"created": "Wed, 11 Jul 2007 18:48:51 GMT"
},
{
"version": "v3",
"created": "Wed, 22 Aug 2007 15:03:56 GMT"
}
] | 2009-04-30T00:00:00 | [
[
"Chandia",
"Osvaldo",
""
],
[
"Tonin",
"Mario",
""
]
] |
0707.0655 | Markus Janousch | B. P. Andreasson, M. Janousch, U. Staub, G. I. Meijer, B. Delley | Resistive Switching in Cr doped SrTiO3: An X-ray Absorption Spectroscopy
study | 14 pages, 4 figures, Proceedings of the E-MRS 2007 spring meeting | null | null | null | cond-mat.mtrl-sci cond-mat.str-el | null | X-ray absorption spectroscopy was used to study the microscopic origin of
conductance and resistive switching in chromium doped strontium titanate
(Cr:SrTiO3). Differences in the x-ray absorption near edge spectroscopy (XANES)
at the Cr K-edge indicate that the valence of Cr changes from 3+ to 4+
underneath the anode of our sample device after the application of an electric
field. Spatially resolved x-ray fluorescence microscopy ($\mu$-XRF) maps show
that the Cr4+ region retracts from the anode-Cr:SrTiO3 interface after a
conducting state has been achieved. This interface region is studied with
extended x-ray absorption fine structure (EXAFS) and the results are compared
with structural parameters obtained from density functional theory (DFT)
calculations. They confirm that oxygen vacancies which are localized at the
octahedron with a Cr at its center are introduced at the interface. It is
proposed that the switching state is not due to a valence change of chromium
but caused by changes of oxygen vacancies at the interface.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 16:16:47 GMT"
}
] | 2007-07-05T00:00:00 | [
[
"Andreasson",
"B. P.",
""
],
[
"Janousch",
"M.",
""
],
[
"Staub",
"U.",
""
],
[
"Meijer",
"G. I.",
""
],
[
"Delley",
"B.",
""
]
] |
0707.0656 | Andreas Muller | Andreas Muller, Edward B. Flagg, Pablo Bianucci, Xiaoyong Wang, Dennis
G. Deppe, Wenquan Ma, Jiayu Zhang, Min Xiao, Gregory J. Salamo, and Chih-Kang
Shih | Resonance fluorescence from a coherently driven semiconductor quantum
dot in a cavity | 5 pages, 4 figures | null | 10.1103/PhysRevLett.99.187402 | null | cond-mat.mtrl-sci cond-mat.other | null | We show that resonance fluorescence, i.e. the resonant emission of a
coherently driven two-level system, can be realized with a semiconductor
quantum dot. The dot is embedded in a planar optical micro-cavity and excited
in a wave-guide mode so as to discriminate its emission from residual laser
scattering. The transition from the weak to the strong excitation regime is
characterized by the emergence of oscillations in the first-order correlation
function of the fluorescence, g(t), as measured by interferometry. The
measurements correspond to a Mollow triplet with a Rabi splitting of up to 13.3
micro eV. Second-order-correlation measurements further confirm non-classical
light emission.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 16:29:49 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Muller",
"Andreas",
""
],
[
"Flagg",
"Edward B.",
""
],
[
"Bianucci",
"Pablo",
""
],
[
"Wang",
"Xiaoyong",
""
],
[
"Deppe",
"Dennis G.",
""
],
[
"Ma",
"Wenquan",
""
],
[
"Zhang",
"Jiayu",
""
],
[
"Xiao",
"Min",
""
],
[
"Salamo",
"Gregory J.",
""
],
[
"Shih",
"Chih-Kang",
""
]
] |
0707.0657 | Aleksandrs Aleksejevs | A. Aleksejevs, S. Barkanova, P. G. Blunden, N. Deg | Electroweak Hard Photon Bremsstrahlung in Electron-Nucleon Scattering | 17 pages, 2 figures, results unchanged, corrected caption for table
#3 | null | null | null | nucl-th | null | One way to treat the infrared divergences of the electroweak
Next-to-Leading-Order (NLO) differential cross sections to parity-violating
(PV) electron-proton scattering is by adding soft-photon emission contribution.
Although more physical, the results are left with a logarithmic dependence on
the photon detector acceptance, which can only be eliminated by considering
Hard Photon Bremsstrahlung (HPB) contribution. Here we present a treatment of
HPB for PV electron-proton scattering. HPB differential cross sections for
electron-proton scattering have been computed using the experimental values of
nucleon form factors. The final results are expressed through kinematic
parameters, making it possible to apply the computed PV HPB differential cross
sections for the analysis of data of a range of current and proposed
experiments.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 16:30:49 GMT"
},
{
"version": "v2",
"created": "Wed, 18 Jul 2007 14:21:40 GMT"
}
] | 2007-07-18T00:00:00 | [
[
"Aleksejevs",
"A.",
""
],
[
"Barkanova",
"S.",
""
],
[
"Blunden",
"P. G.",
""
],
[
"Deg",
"N.",
""
]
] |
0707.0658 | Thomas Vojta | Thomas Vojta and J. A. Hoyos | Quantum Phase Transitions on Percolating Lattices | 10 pages, invited talk at "Recent Progress in Many-Body Theories 14" | null | 10.1142/9789812779885_0030 | null | cond-mat.stat-mech cond-mat.str-el | null | When a quantum many-particle system exists on a randomly diluted lattice, its
intrinsic thermal and quantum fluctuations coexist with geometric fluctuations
due to percolation. In this paper, we explore how the interplay of these
fluctuations influences the phase transition at the percolation threshold.
While it is well known that thermal fluctuations generically destroy long-range
order on the critical percolation cluster, the effects of quantum fluctuations
are more subtle. In diluted quantum magnets with and without dissipation, this
leads to novel universality classes for the zero-temperature percolation
quantum phase transition. Observables involving dynamical correlations display
nonclassical scaling behavior that can nonetheless be determined exactly in two
dimensions.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 16:32:36 GMT"
}
] | 2017-08-23T00:00:00 | [
[
"Vojta",
"Thomas",
""
],
[
"Hoyos",
"J. A.",
""
]
] |
0707.0659 | Yuly Billig | Yuly Billig, Alexander Molev, Ruibin Zhang | Differential equations in vertex algebras and simple modules for the Lie
algebra of vector fields on a torus | null | null | null | null | math.RT | null | We study irreducible representations for the Lie algebra of vector fields on
a 2-dimensional torus constructed using the generalized Verma modules. We show
that for a certain choice of parameters these representations remain
irreducible when restricted to a loop subalgebra in the Lie algebra of vector
fields. We prove this result by studying vertex algebras associated with the
Lie algebra of vector fields on a torus and solving non-commutative
differential equations that we derive using the vertex algebra technique.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 16:44:09 GMT"
}
] | 2007-07-05T00:00:00 | [
[
"Billig",
"Yuly",
""
],
[
"Molev",
"Alexander",
""
],
[
"Zhang",
"Ruibin",
""
]
] |
0707.0660 | Vladimir Vovk | Vladimir Vovk | Strong confidence intervals for autoregression | 7 pages, 2 tables, 2 figures | null | null | null | math.ST stat.ME stat.TH | null | In this short note I apply the methodology of game-theoretic probability to
calculating non-asymptotic confidence intervals for the coefficient of a simple
first order scalar autoregressive model. The most distinctive feature of the
proposed procedure is that with high probability it produces confidence
intervals that always cover the true parameter value when applied sequentially.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 16:44:59 GMT"
}
] | 2011-11-10T00:00:00 | [
[
"Vovk",
"Vladimir",
""
]
] |
0707.0661 | Susana Judith Landau | Mercedes E. Mosquera, Claudia G. Scoccola, Susana J. Landau and Hector
Vucetich | Time variation of the fine structure constant in the early universe and
the Bekenstein model | 13 pages, 8 figures,version accepted to be published in Astronomy and
Astrophysics | Astron.Astrophys. 478 (2008) 675 | 10.1051/0004-6361:20078605 | null | astro-ph gr-qc hep-ph physics.atom-ph | null | We calculate bounds on the variation of the fine structure constant at the
time of primordial nucleosynthesis and at the time of neutral hydrogen
formation. We use these bounds and other bounds from the late universe to test
Bekenstein model. We modify the Kawano code, CAMB and CosmoMC in order to
include the possible variation of the fine structure constant. We use
observational primordial abundances of $\De$, $\He$ and $\Li$, recent data from
the Cosmic Microwave Background and the 2dFGRS power spectrum, to obtain bounds
on the variation of $\alpha$. We calculate a piecewise solution to the scalar
field equation of Bekenstein model in two different regimes; i) matter and
radiation, ii) matter and cosmological constant. We match both solutions with
appropriate boundary conditions. We perform a statistical analysis using the
bounds obtained from the early universe and other bounds from the late universe
to constrain the free parameters of the model. Results are consistent with no
variation of $\alpha$ in the early universe. Limits on $\alpha$ are
inconsistent with the scale length of the theory $l$ being larger than Planck
scale. In order to fit all observational and experimental data, the assumption
$l>L_p$ implied in Bekenstein's model has to be relaxed.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 17:24:45 GMT"
},
{
"version": "v2",
"created": "Thu, 12 Jul 2007 14:12:43 GMT"
},
{
"version": "v3",
"created": "Thu, 8 Nov 2007 19:20:36 GMT"
}
] | 2008-03-07T00:00:00 | [
[
"Mosquera",
"Mercedes E.",
""
],
[
"Scoccola",
"Claudia G.",
""
],
[
"Landau",
"Susana J.",
""
],
[
"Vucetich",
"Hector",
""
]
] |
0707.0662 | Felix Ritort | M. Manosas, J.-D. Wen, P. T. X. Li, S. B. Smith, C. Bustamante, I.
Tinoco, Jr., F. Ritort | Force unfolding kinetics of RNA using optical tweezers. II. Modeling
experiments | PDF file, 32 pages including 9 figures plus supplementary material | Biophysical Journal, 92 (2007) 3010-3021 | 10.1529/biophysj.106.094243 | null | physics.bio-ph cond-mat.soft cond-mat.stat-mech q-bio.BM | null | By exerting mechanical force it is possible to unfold/refold RNA molecules
one at a time. In a small range of forces, an RNA molecule can hop between the
folded and the unfolded state with force-dependent kinetic rates. Here, we
introduce a mesoscopic model to analyze the hopping kinetics of RNA hairpins in
an optical tweezers setup. The model includes different elements of the
experimental setup (beads, handles and RNA sequence) and limitations of the
instrument (time lag of the force-feedback mechanism and finite bandwidth of
data acquisition). We investigated the influence of the instrument on the
measured hopping rates. Results from the model are in good agreement with the
experiments reported in the companion article (1). The comparison between
theory and experiments allowed us to infer the values of the intrinsic
molecular rates of the RNA hairpin alone and to search for the optimal
experimental conditions to do the measurements. We conclude that long handles
and soft laser traps represent the best conditions to extract rate estimates
that are closest to the intrinsic molecular rates. The methodology and
rationale presented here can be applied to other experimental setups and other
molecules.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 15:40:05 GMT"
}
] | 2012-08-27T00:00:00 | [
[
"Manosas",
"M.",
""
],
[
"Wen",
"J. -D.",
""
],
[
"Li",
"P. T. X.",
""
],
[
"Smith",
"S. B.",
""
],
[
"Bustamante",
"C.",
""
],
[
"Tinoco,",
"I.",
"Jr."
],
[
"Ritort",
"F.",
""
]
] |
0707.0663 | Gerd Bergmann | Gerd Bergmann, Yaqi Tao, Jia G. Lu, and Richard S. Thompson | Spacial Modulation of the Magnetization in Cobalt Nanowires | null | null | null | null | cond-mat.mes-hall cond-mat.str-el | null | Cobalt nanowires with a diameter in the range between 50 to 100nm can be
prepared as single-crystal wires with the easy axis (the c-axis) perpendicular
to the wire axis. The competition between the crystal anisotropy and
demagnetization energy frustrates the magnetization direction. A periodic
modulation of the angle between M and the wire axis yields a lower energy.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 16:56:13 GMT"
}
] | 2007-07-05T00:00:00 | [
[
"Bergmann",
"Gerd",
""
],
[
"Tao",
"Yaqi",
""
],
[
"Lu",
"Jia G.",
""
],
[
"Thompson",
"Richard S.",
""
]
] |
0707.0664 | Thomas Prellberg | Peter Cameron, Thomas Prellberg and Dudley Stark | Asymptotic enumeration of 2-covers and line graphs | null | null | null | null | math.CO | null | In this paper we find asymptotic enumerations for the number of line graphs
on $n$-labelled vertices and for different types of related combinatorial
objects called 2-covers.
We find that the number of 2-covers, $s_n$, and proper 2-covers, $t_n$, on
$[n]$ both have asymptotic growth $$ s_n\sim t_n\sim
B_{2n}2^{-n}\exp(-\frac12\log(2n/\log n))= B_{2n}2^{-n}\sqrt{\frac{\log
n}{2n}}, $$ where $B_{2n}$ is the $2n$th Bell number, while the number of
restricted 2-covers, $u_n$, restricted, proper 2-covers on $[n]$, $v_n$, and
line graphs $l_n$, all have growth $$ u_n\sim v_n\sim l_n\sim
B_{2n}2^{-n}n^{-1/2}\exp(-[\frac12\log(2n/\log n)]^2). $$
In our proofs we use probabilistic arguments for the unrestricted types of
2-covers and and generating function methods for the restricted types of
2-covers and line graphs.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 16:59:40 GMT"
}
] | 2007-07-05T00:00:00 | [
[
"Cameron",
"Peter",
""
],
[
"Prellberg",
"Thomas",
""
],
[
"Stark",
"Dudley",
""
]
] |
0707.0665 | Tomas Jungwirth | T. Jungwirth, Jairo Sinova, A. H. MacDonald, B. L. Gallagher, V.
Novak, K. W. Edmonds, A. W. Rushforth, R. P. Campion, C. T. Foxon, L. Eaves,
K. Olejnik, J. Masek, S.-R. Eric Yang, J. Wunderlich, C. Gould, L. W.
Molenkamp, T. Dietl, and H. Ohno | On the character of states near the Fermi level in (Ga,Mn)As: impurity
to valence band crossover | 10 pages, 12 figures | null | 10.1103/PhysRevB.76.125206 | null | cond-mat.mtrl-sci | null | We discuss the character of states near the Fermi level in Mn doped GaAs, as
revealed by a survey of dc transport and optical studies over a wide range of
Mn concentrations. A thermally activated valence band contribution to dc
transport, a mid-infrared peak at energy hbar omega approx 200 meV in the ac-
conductivity, and the hot photoluminescence spectra indicate the presence of an
impurity band in low doped (<<1% Mn) insulating GaAs:Mn materials. Consistent
with the implications of this picture, both the impurity band ionization energy
inferred from the dc transport and the position of the mid-infrared peak move
to lower energies and the peak broadens with increasing Mn concentration. In
metallic materials with > 2% doping, no traces of Mn-related activated
contribution can be identified in dc-transport, suggesting that the impurity
band has merged with the valence band. No discrepancies with this perception
are found when analyzing optical measurements in the high-doped GaAs:Mn. A
higher energy (hbar omega approx 250 meV) mid-infrared feature which appears in
the metallic samples is associated with inter-valence band transitions. Its
red-shift with increased doping can be interpreted as a consequence of
increased screening which narrows the localized-state valence-band tails and
weakens higher energy transition amplitudes. Our examination of the dc and ac
transport characteristics of GaAs:Mn is accompanied by comparisons with its
shallow acceptor counterparts, confirming the disordered valence band picture
of high-doped metallic GaAs:Mn material.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 17:12:23 GMT"
},
{
"version": "v2",
"created": "Thu, 5 Jul 2007 11:13:58 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Jungwirth",
"T.",
""
],
[
"Sinova",
"Jairo",
""
],
[
"MacDonald",
"A. H.",
""
],
[
"Gallagher",
"B. L.",
""
],
[
"Novak",
"V.",
""
],
[
"Edmonds",
"K. W.",
""
],
[
"Rushforth",
"A. W.",
""
],
[
"Campion",
"R. P.",
""
],
[
"Foxon",
"C. T.",
""
],
[
"Eaves",
"L.",
""
],
[
"Olejnik",
"K.",
""
],
[
"Masek",
"J.",
""
],
[
"Yang",
"S. -R. Eric",
""
],
[
"Wunderlich",
"J.",
""
],
[
"Gould",
"C.",
""
],
[
"Molenkamp",
"L. W.",
""
],
[
"Dietl",
"T.",
""
],
[
"Ohno",
"H.",
""
]
] |
0707.0666 | Eva Glasmachers | Eva Glasmachers and Gerhard Knieper | Characterization of geodesic flows on T^2 with and without positive
topological entropy | 19 pages, 8 figures | null | null | null | math.DS math.DG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In the present work we consider the behavior of the geodesic flow on the unit
tangent bundle of the 2-torus $T^2$ for an arbitrary Riemannian metric. A
natural non-negative quantity which measures the complexity of the geodesic
flow is the topological entropy. In particular, positive topological entropy
implies chaotic behavior on an invariant set in the phase space of positive
Hausdorff-dimension (horseshoe). We show that in the case of zero topological
entropy the flow has properties similar to integrable systems. In particular
there exists a non-trivial continuous constant of motion which measures the
direction of geodesics lifted onto the universal covering $\Br^2$. Furthermore,
those geodesics travel in strips bounded by Euclidean lines. Moreover we derive
necessary and sufficient conditions for vanishing topological entropy involving
intersection properties of single geodesics on $T^2$.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 17:15:20 GMT"
},
{
"version": "v2",
"created": "Wed, 10 Feb 2010 19:58:59 GMT"
},
{
"version": "v3",
"created": "Tue, 15 Jun 2010 20:32:20 GMT"
},
{
"version": "v4",
"created": "Wed, 30 Jun 2010 05:55:15 GMT"
}
] | 2010-07-01T00:00:00 | [
[
"Glasmachers",
"Eva",
""
],
[
"Knieper",
"Gerhard",
""
]
] |
0707.0667 | Jorge S\'anchez-Ruiz | Julio I. de Vicente, Silvia Gandy, Jorge S\'anchez-Ruiz | Information entropy of Gegenbauer polynomials of integer parameter | 19 pages, 1 Postscript figure | J. Phys. A: Math. Theor. 40, 8345-8361 (2007) | 10.1088/1751-8113/40/29/010 | null | math-ph math.CA math.MP quant-ph | null | The position and momentum information entropies of $D$-dimensional quantum
systems with central potentials, such as the isotropic harmonic oscillator and
the hydrogen atom, depend on the entropies of the (hyper)spherical harmonics.
In turn, these entropies are expressed in terms of the entropies of the
Gegenbauer (ultraspherical) polynomials $C_n^{(\lambda)}(x)$, the parameter
$\lambda$ being either an integer or a half-integer number. Up to now, however,
the exact analytical expression of the entropy of Gegenbauer polynomials of
arbitrary degree $n$ has only been obtained for the particular values of the
parameter $\lambda=0,1,2$. Here we present a novel approach to the evaluation
of the information entropy of Gegenbauer polynomials, which makes use of
trigonometric representations for these polynomials and complex integration
techniques. Using this method, we are able to find the analytical expression of
the entropy for arbitrary values of both $n$ and $\lambda\in\mathbb{N}$.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 17:22:37 GMT"
}
] | 2007-08-27T00:00:00 | [
[
"de Vicente",
"Julio I.",
""
],
[
"Gandy",
"Silvia",
""
],
[
"Sánchez-Ruiz",
"Jorge",
""
]
] |
0707.0668 | Heng-Yu Chen HYC | Heng-Yu Chen, Nick Dorey and Rui F. Lima Matos | Quantum Scattering of Giant Magnons | 47 pages, 2 figures. References added, to be submitted to JHEP | JHEP 0709:106,2007 | 10.1088/1126-6708/2007/09/106 | DAMTP-07-51 | hep-th | null | We perform a first-principles semi-classical computation of the one-loop
corrections to the dispersion relation and S-matrix of Giant Magnons in AdS_5 x
S^5 string theory. The results agree exactly with expectations based on the
strong coupling expansion of the exact Asymptotic Bethe Ansatz equations. In
particular we reproduce the Hernandez-Lopez term in the dressing phase.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 17:32:04 GMT"
},
{
"version": "v2",
"created": "Tue, 21 Aug 2007 18:53:43 GMT"
}
] | 2009-04-30T00:00:00 | [
[
"Chen",
"Heng-Yu",
""
],
[
"Dorey",
"Nick",
""
],
[
"Matos",
"Rui F. Lima",
""
]
] |
0707.0669 | Jose Edgar Madriz Aguilar | Lucio Fabio P. da Silva and Jose Edgar Madriz Aguilar | Quintessential inflation from 5D warped product spaces on a dynamical
foliation | 7 pages, 1 figure Accepted for publication in Modern Physics Letters
A | Mod.Phys.Lett.A23:1213-1221,2008 | 10.1142/S0217732308025747 | null | gr-qc astro-ph hep-th | null | Assuming the existence of a 5D purely kinetic scalar field on the class of
warped product spaces we investigate the possibility of mimic both an
inflationary and a quintessential scenarios on 4D hypersurfaces, by
implementing a dynamical foliation on the fifth coordinate instead of a
constant one. We obtain that an induced chaotic inflationary scenario with a
geometrically induced scalar potential and an induced quasi-vacuum equation of
state on 4D dynamical hypersurfaces is possible. While on a constant foliation
the universe can be considered as matter dominated today, in a family of 4D
dynamical hypersurfaces the universe can be passing for a period of accelerated
expansion with a deceleration parameter nearly -1. This effect of the dynamical
foliation results negligible at the inflationary epoch allowing for a chaotic
scenario and becomes considerable at the present epoch allowing a
quintessential scenario.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 17:26:25 GMT"
},
{
"version": "v2",
"created": "Wed, 26 Sep 2007 20:18:51 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"da Silva",
"Lucio Fabio P.",
""
],
[
"Aguilar",
"Jose Edgar Madriz",
""
]
] |
0707.0670 | Csaba Toke Dr. | Csaba Toke, Jainendra K. Jain | Theoretical study of even denominator fractions in graphene: Fermi sea
versus paired states of composite fermions | null | PRB 76, 081403 (2007) | 10.1103/PhysRevB.76.081403 | null | cond-mat.mes-hall cond-mat.str-el | null | The physics of the state at even denominator fractional fillings of Landau
levels depends on the Coulomb pseudopotentials, and produces, in different GaAs
Landau levels, a composite fermion Fermi sea, a stripe phase, or, possibly, a
paired composite fermion state. We consider here even denominator fractions in
graphene, which has different pseudopotentials as well as a possible four fold
degeneracy of each Landau level. We test various composite fermion Fermi sea
wave functions (fully polarized, SU(2) singlet, SU(4) singlet) as well as the
paired composite fermion states in the n=0 and $n=1$ Landau levels and predict
that (i) the paired states are not favorable, (ii) CF Fermi seas occur in both
Landau levels, and (iii) an SU(4) singlet composite fermion Fermi sea is
stabilized in the appropriate limit. The results from detailed microscopic
calculations are generally consistent with the predictions of the mean field
model of composite fermions.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 17:32:18 GMT"
},
{
"version": "v2",
"created": "Wed, 22 Aug 2007 10:29:09 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Toke",
"Csaba",
""
],
[
"Jain",
"Jainendra K.",
""
]
] |
0707.0671 | Surya Ramana D | Gyan Prakash and D.S. Ramana | The Large Sieve Inequality for Integer Polynomial Amplitudes | 6 pages | null | null | null | math.NT | null | We obtain a close to the best possible version of the large sieve inequality
with amplitudes given by the values of a polynomial with integer coefficients
of degree $\geq 2$.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 17:32:57 GMT"
}
] | 2007-07-05T00:00:00 | [
[
"Prakash",
"Gyan",
""
],
[
"Ramana",
"D. S.",
""
]
] |
0707.0672 | Davide Fedele | D. Fedele (1,2), M. E. van den Ancker (2), M. G. Petr-Gotzens (2), N.
Ageorges (2) and P. Rafanelli (1) ((1) Universita' di Padova, (2) ESO) | Optical and infrared properties of V1647 Orionis during the 2003-2006
outburst. I The reflection nebula | 8 pages, 7 figures, in press | null | 10.1051/0004-6361:20077724 | null | astro-ph | null | Aims: The recent outburst of the young eruptive star V1647 Orionis has
produced a spectacular appearance of a new reflection nebula in Orion (McNeil's
nebula). We present an optical/near infrared investigation of McNeil's nebula.
This analysis is aimed at determining the morphology, temporal evolution and
nature of the nebula and its connection to the outburst.
Method: We performed multi epoch B, V, R, I, z, and K imaging of McNeil's
nebula and V1647 Ori as well as K_S imaging polarimetry. The multiband imaging
allows us to reconstruct the extinction map inside the nebula. Through
polarimetric observations we attempt to disentangle the emission from the
nebula from that of the accretion disk around V1647 Ori. We also attempt to
resolve the small spatial scale structure of the illuminating source.
Results: The energy distribution and temporal evolution of McNeil's nebula
mimic that of the illuminating source. The extinction map reveals a region of
higher extinction in the direction of V1647 Ori. Excluding foreground
extionction, the optical extinction due to McNeil's nebula in the direction of
V1647 Ori is A_V ~ 6.5 mag. The polarimetric measurement shows a compact high
polarization emission around V1647 Ori. The percentage of K_S band linear
polarization goes from 10 -- 20 %. The vectors are all well aligned with a
position angle of 90 +/- 9 degree East of North. This may correspond to the
orientation of a possible accretion disk around V1647 Ori. These findings
suggest that the appearance of McNeil's nebula is due to reflection of light by
pre-existing material in the surroundings of V1647 Ori. We also report on the
discovery of a new candidate brown dwarf or protostar in the vicinity of V1647
Ori as well as the presence of clumpy structure within HH 22A.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 17:41:13 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Fedele",
"D.",
"",
"Universita' di Padova",
"ESO"
],
[
"Ancker",
"M. E. van den",
"",
"ESO"
],
[
"Petr-Gotzens",
"M. G.",
"",
"ESO"
],
[
"Ageorges",
"N.",
"",
"ESO"
],
[
"Rafanelli",
"P.",
"",
"Universita' di Padova"
]
] |
0707.0673 | Eva Leschinsky | Eva Leschinsky | Minimal geodesics and topological entropy on T^2 | 12 pages | null | null | null | math.DS math.DG | null | Let (T^2, g) be a two-dimensional Riemannian torus. In this paper we prove
that the topological entropy of the geodesic flow restricted to the set of
initial conditions of minimal geodesics vanishes, independent of the choice of
the Riemannian metric.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 17:47:49 GMT"
}
] | 2007-07-05T00:00:00 | [
[
"Leschinsky",
"Eva",
""
]
] |
0707.0674 | Slobodan Vrhovac | I. Lon\v{c}arevi\'c, Lj. Budinski-Petkovi\'c and S. B. Vrhovac | Simulation study of random sequential adsorption of mixtures on a
triangular lattice | 11 figures, 2 tables | null | 10.1140/epje/i2007-10206-4 | null | cond-mat.stat-mech cond-mat.soft | null | Random sequential adsorption of binary mixtures of extended objects on a
two-dimensional triangular lattice is studied numerically by means of Monte
Carlo simulations. The depositing objects are formed by self-avoiding random
walks on the lattice. We concentrate here on the influence of the symmetry
properties of the shapes on the kinetics of the deposition processes in
two-component mixtures. Approach to the jamming limit in the case of mixtures
is found to be exponential, of the form: $\theta(t) \sim
\theta_{jam}-\Delta\theta \exp (-t/\sigma),$ and the values of the parameter
$\sigma$ are determined by the order of symmetry of the less symmetric object
in the mixture. Depending on the local geometry of the objects making the
mixture, jamming coverage of a mixture can be either greater than both
single-component jamming coverages or it can be in between these values.
Results of the simulations for various fractional concentrations of the objects
in the mixture are also presented.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 17:54:15 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Lončarević",
"I.",
""
],
[
"Budinski-Petković",
"Lj.",
""
],
[
"Vrhovac",
"S. B.",
""
]
] |
0707.0675 | Armand Niederberger | Armand Niederberger, Thomas Schulte, Jan Wehr, Maciej Lewenstein,
Laurent Sanchez-Palencia, Krzysztof Sacha | Disorder-Induced Order in Two-Component Bose-Einstein Condensates | 4 pages, 3 figures | Phys. Rev. Lett. 100, 030403 (2008) | 10.1103/PhysRevLett.100.030403 | null | cond-mat.other cond-mat.dis-nn | null | We propose and analyze a general mechanism of disorder-induced order in
two-component Bose-Einstein condensates, analogous to corresponding effects
established for XY spin models. We show that a random Raman coupling induces a
relative phase of pi/2 between two BECs and that the effect is robust. We
demonstrate it in 1D, 2D and 3D at T=0 and present evidence that it persists at
small T>0. Applications to phase control in ultracold spinor condensates are
discussed.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 17:54:37 GMT"
},
{
"version": "v2",
"created": "Wed, 11 Jul 2007 14:35:57 GMT"
},
{
"version": "v3",
"created": "Thu, 21 Feb 2008 17:59:20 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Niederberger",
"Armand",
""
],
[
"Schulte",
"Thomas",
""
],
[
"Wehr",
"Jan",
""
],
[
"Lewenstein",
"Maciej",
""
],
[
"Sanchez-Palencia",
"Laurent",
""
],
[
"Sacha",
"Krzysztof",
""
]
] |
0707.0676 | Jaime Vladimir Torres-Heredia Julca | Jaime Vladimir Torres-Heredia Julca | A geometrical link between the circle and sexagesimal system | 24 pages, 36 figures | null | null | null | math.HO math.GM | null | This paper presents a simple geometrical fact which could relate to the
history of mathematics and astronomy. This fact shows a natural link between
the circle and the multiples of 6 and it makes it possible to obtain a simple
representation of the 12 months of the year, the 24 hours of the day, the 30
days (average number) of the month and the 360 days (approximate number) of the
year, which brings us closer to the sexagesimal division of time. Moreover this
representation reminds one of the movement of the planets around a centre.
Using this fact one will be able also to find geometrically the principal
divisor of number 60, to represent numbers in base 60 with a kind of abacus or
calculation table and to make a division of the circle into 6 and 12 equal
parts. Afterwards one will be able to obtain a division in 360 unequal parts
but relatively close to one another, and the goal isn't precisely to obtain an
optimal division of the circle in 360 equal parts but to prove that the idea to
divide the circle in 360 equal parts can subsequently be suggested by these
geometrical facts that have been showed. In this article the author will not
answer the following questions: a) What is the origin of the sexagesimal
system? b) By which way could one manage to adopt the sexagesimal system
starting from the knowledge of the facts exposed in this article and starting
from the knowledge of the astronomical data? These questions could be treated,
using information of this article, by the readers or later on by the author.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 18:00:02 GMT"
}
] | 2007-07-05T00:00:00 | [
[
"Julca",
"Jaime Vladimir Torres-Heredia",
""
]
] |
0707.0677 | Roman Zwicky | Roman Zwicky | Unparticles at heavy flavour scales: CP violating phenomena | 33 pages, 9 figures | Phys.Rev.D77:036004,2008 | 10.1103/PhysRevD.77.036004 | DCPT/07/58, IPPP/07/29 | hep-ph | null | Coupling the scale invariant unparticle sector to flavour physics and
assuming that it remains scale invariant we investigate its consequences in
heavy flavour physics. A drastic feature of unparticle physics is an unusual
phase leading to novel CP violating phenomena. We consider the CP asymmetry in
the leptonic decay B^+ -> tau^+ nu and the hadronic decay B_d -> D^+D^-, taking
into account constraints of branching ratios and time dependent CP asymmetries.
Generic plots are shown and it turns out that there exist parameters for which
the CP violation is maximal. A prediction of a large CP asymmetry in B_d ->
D^+D^- is difficult to achieve in other models without contradicting the
current data in other channels. The prediction of a CP asymmetry in leptonic
decays, such as B^+ -> tau^+ nu, is novel. We identify the CP compensating mode
due to the unparticles and show explicitly that it exactly cancels the CP
asymmetry of B^+ -> tau^+ nu as demanded by CPT invariance. Building up on
earlier works we investigate the breaking of scale invaricance, due to the
coupling to the Higgs and the size of the effects in the weak sector resorting
to a dimensional analysis. An enhancement is observed on the grounds of the
relevance of the unparticle interaction operator as compared to the weak
four-Fermi term.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 18:25:34 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Zwicky",
"Roman",
""
]
] |
0707.0678 | Tim Roemer | Aldo Conca, Tim Roemer | Generic initial ideals and fibre products | 13 pages | Osaka J. Math. 47 (2010), no. 1, 17-32 | null | null | math.AC math.CO | null | We study the behavior of generic initial ideals with respect to fibre
products. In our main result we determine the generic initial ideal of the
fibre product with respect to the reverse lexicographic order. As an
application we compute the symmetric algebraic shifted complex of two disjoint
simplicial complexes as was conjectured by Kalai. This result is the symmetric
analogue of a theorem of Nevo who determined the exterior algebraic shifted
complex of two disjoint simplicial complexes as predicted by Kalai.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 18:34:27 GMT"
}
] | 2021-05-18T00:00:00 | [
[
"Conca",
"Aldo",
""
],
[
"Roemer",
"Tim",
""
]
] |
0707.0679 | Avi Shporer | B. Loeillet, A. Shporer, F. Bouchy, F. Pont, T. Mazeh, J.L. Beuzit, I.
Boisse, X. Bonfils, R. Da Silva, X. Delfosse, M. Desort, A. Ecuvillon, T.
Forveille, F. Galland, A. Gallenne, G. Hebrard, A. M. Lagrange, C. Lovis, M.
Mayor, C. Moutou, F. Pepe, C. Perrier, D. Queloz, D. Segransan, J.P. Sivan,
N. C. Santos, Y. Tsodikovich, S. Udry, A. Vidal-Madjar | Refined parameters and spectroscopic transit of the super-massive planet
HD147506b | Submitted to A&A; V2: Replaced by accepted version | null | 10.1051/0004-6361:20078167 | null | astro-ph | null | In this paper, we report a refined determination of the orbital parameters
and the detection of the Rossiter-McLaughlin effect of the recently discovered
transiting exoplanet HD147506b (HAT-P-2b). The large orbital eccentricity at
the short orbital period of this exoplanet is unexpected and is distinguishing
from other known transiting exoplanets. We performed high-precision radial
velocity spectroscopic observations of HD147506 (HAT-P-2) with the new
spectrograph SOPHIE, mounted on the 1.93 m telescope at the Haute-Provence
observatory (OHP). We obtained 63 new measurements, including 35 on May 14 and
20 on June 11, when the planet was transiting its parent star. The radial
velocity (RV) anomaly observed illustrates that HAT-P-2b orbital motion is set
in the same direction as its parent star spin. The sky-projected angle between
the normal of the orbital plane and the stellar spin axis, \lambda = 0.2 +12.2
-12.5 deg, is consistent with zero. The planetary and stellar radii were
re-determined, yielding R_p = 0.951 +0.039 -0.053 R_Jup, R_s = 1.416 +0.040
-0.062 R_Sun. The mass M_p = 8.62 +0.39 -0.55 M_Jup and radius of HAT-P-2b
indicate a density of 12.5 +2.6 -3.6 g cm^{-3}, suggesting an object in between
the known close-in planets with typical density of the order of 1 g cm^{-3},
and the very low-mass stars, with density greater than 50 g cm^{-3}.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 18:43:21 GMT"
},
{
"version": "v2",
"created": "Thu, 21 Feb 2008 17:07:37 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Loeillet",
"B.",
""
],
[
"Shporer",
"A.",
""
],
[
"Bouchy",
"F.",
""
],
[
"Pont",
"F.",
""
],
[
"Mazeh",
"T.",
""
],
[
"Beuzit",
"J. L.",
""
],
[
"Boisse",
"I.",
""
],
[
"Bonfils",
"X.",
""
],
[
"Da Silva",
"R.",
""
],
[
"Delfosse",
"X.",
""
],
[
"Desort",
"M.",
""
],
[
"Ecuvillon",
"A.",
""
],
[
"Forveille",
"T.",
""
],
[
"Galland",
"F.",
""
],
[
"Gallenne",
"A.",
""
],
[
"Hebrard",
"G.",
""
],
[
"Lagrange",
"A. M.",
""
],
[
"Lovis",
"C.",
""
],
[
"Mayor",
"M.",
""
],
[
"Moutou",
"C.",
""
],
[
"Pepe",
"F.",
""
],
[
"Perrier",
"C.",
""
],
[
"Queloz",
"D.",
""
],
[
"Segransan",
"D.",
""
],
[
"Sivan",
"J. P.",
""
],
[
"Santos",
"N. C.",
""
],
[
"Tsodikovich",
"Y.",
""
],
[
"Udry",
"S.",
""
],
[
"Vidal-Madjar",
"A.",
""
]
] |
0707.0680 | Dionisio Bazeia | D. Bazeia, F.A. Brito, F.G. Costa | First-order framework and domain-wall/brane-cosmology correspondence | Revtex4, 10 pages, 7 figures; version to appear in PLB | Phys.Lett.B661:179-185,2008 | 10.1016/j.physletb.2008.02.016 | null | hep-th | null | We address the possibility of finding domain wall solutions from cosmological
solutions in brane cosmology. We find first-order equations for corresponding
cosmology/domain wall solutions induced on 3-branes. The quadratic term of
energy density in the induced Friedmann equation plays a non-standard role and
we discuss the way the standard cosmological and domain wall models are
recovered as the brane tension becomes large and show how they can be described
by four-dimensional supergravity action in such a limit. Finally, we show that
gravity on the 3-brane is locally localized as one moves away from the
two-dimensional domain walls living on the brane.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 18:42:21 GMT"
},
{
"version": "v2",
"created": "Fri, 27 Jul 2007 15:14:08 GMT"
},
{
"version": "v3",
"created": "Wed, 16 Jan 2008 18:16:21 GMT"
},
{
"version": "v4",
"created": "Mon, 11 Feb 2008 19:06:07 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Bazeia",
"D.",
""
],
[
"Brito",
"F. A.",
""
],
[
"Costa",
"F. G.",
""
]
] |
0707.0681 | Valerii Dryuma sem | Valerii Dryuma | On the Equations of Nonstationary Transonic Gas Flows | 8 pages | null | null | null | nlin.SI | null | The method of point transformation of the functions and variables for
construction of particular solutions of the Equations of Nonstationary
Transonic Gas Flows is used.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 19:18:16 GMT"
}
] | 2007-07-05T00:00:00 | [
[
"Dryuma",
"Valerii",
""
]
] |
0707.0682 | Francisco (Paco) Guinea | F. Guinea, M. I. Katsnelson, and M. A. H. Vozmediano | Midgap states and charge inhomogeneities in corrugated graphene | null | Phys. Rev. B, vol. 77, 075422 (2008) | 10.1103/PhysRevB.77.075422 | null | cond-mat.mes-hall cond-mat.mtrl-sci | null | We study the changes induced by the effective gauge field due to ripples on
the low energy electronic structure of graphene. We show that zero energy
Landau levels will form, associated to the smooth deformation of the graphene
layer, when the height corrugation, $h$, and the length of the ripple, $l$, are
such that $h^2 / (l a) \gtrsim 1$, where $a$ is the lattice constant. The
existence of localized levels gives rise to a large compressibility at zero
energy, and to the enhancement of instabilities arising from electron-electron
interactions including electronic phase separation. The combined effect of the
ripples and an external magnetic field breaks the valley symmetry of graphene
leading to the possibility of valley selection.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 19:21:08 GMT"
},
{
"version": "v2",
"created": "Wed, 19 Dec 2007 12:03:38 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Guinea",
"F.",
""
],
[
"Katsnelson",
"M. I.",
""
],
[
"Vozmediano",
"M. A. H.",
""
]
] |
0707.0683 | Gianni Manno | Ricardo Alonso Blanco, Gianni Manno, Fabrizio Pugliese | Normal forms for parabolic Monge-Ampere equations | 18 pages | null | null | null | math.DG math.AP | null | We find normal forms for parabolic Monge-Ampere equations. Of these, the most
general one holds for any equation admitting a complete integral. Moreover, we
explicitly give the determining equation for such integrals; restricted to the
analytic case, this equation is shown to have solutions. The other normal forms
exhaust the different classes of parabolic Monge-Ampere equations with symmetry
properties, namely, the existence of classical or nonholonomic intermediate
integrals. Our approach is based on the equivalence between parabolic
Monge-Ampere equations and particular distributions on a contact manifold, and
involves a classification of vector fields lying in the contact structure.
These are divided into three types and described in terms of the simplest ones
(characteristic fields of first order PDE's).
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 19:25:50 GMT"
},
{
"version": "v2",
"created": "Thu, 16 Aug 2007 19:53:39 GMT"
},
{
"version": "v3",
"created": "Sat, 15 Sep 2007 14:14:47 GMT"
}
] | 2007-09-15T00:00:00 | [
[
"Blanco",
"Ricardo Alonso",
""
],
[
"Manno",
"Gianni",
""
],
[
"Pugliese",
"Fabrizio",
""
]
] |
0707.0684 | Stefan Noll | S. Noll, D. Pierini, M. Pannella, S. Savaglio | Presence of dust with a UV bump in massive, star-forming galaxies at 1 <
z < 2.5 | 19 pages, 15 figures, accepted for publication in A&A | null | 10.1051/0004-6361:20077067 | null | astro-ph | null | Fundamental properties of the extinction curve, like the slope in the
rest-frame ultraviolet (UV) and the presence/absence of a broad absorption
excess centred at 2175 A (the UV bump), are investigated for a sample of 108
massive, star-forming galaxies at 1 < z < 2.5, selected from the FDF
Spectroscopic Survey, the K20 survey, and the GDDS. These characteristics are
constrained from a parametric description of the UV spectral energy
distribution (SED) of a galaxy, as enforced by combined stellar population and
radiative transfer models for different geometries, dust/stars configurations
and dust properties. In at least one third of the sample, there is a robust
evidence for extinction curves with at least a moderate UV bump. The presence
of the carriers of the UV bump is more evident in galaxies with UV SEDs
suffering from heavy reddening. We interpret these results as follows. The
sample objects possess different mixtures of dust grains and molecules
producing extinction curves in between the average ones of the Small and Large
Magellanic Cloud, where the UV bump is absent or modest, respectively. Most of
the dust embeds the UV-emitting stellar populations or is distributed out of
the galaxy mid-plane. Alternatively, even dust with a pronounced UV bump, as
for the average Milky-Way extinction curve, can be present and distributed in
the galaxy mid-plane. In this case, variations of the continuum scattering
albedo with wavelength or an age-dependent extinction are not sufficient to
explain the previous trend with reddening. Hence, additional extraplanar dust
has to be invoked. The data suggest that the carriers of the UV bump are
associated with intermediate-age stellar populations, while they survive in the
harshest UV-radiation fields owing to dust self-shielding. [abridged]
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 19:53:50 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Noll",
"S.",
""
],
[
"Pierini",
"D.",
""
],
[
"Pannella",
"M.",
""
],
[
"Savaglio",
"S.",
""
]
] |
0707.0685 | Joseph V. Emerson | Joseph Emerson, Marcus Silva, Osama Moussa, Colm Ryan, Martin
Laforest, Jonathan Baugh, David G. Cory, Raymond Laflamme | Symmetrised Characterisation of Noisy Quantum Processes | About 12 pages, 5 figures | Science 317, 1893-1896 (2007). | 10.1126/science.1145699 | null | quant-ph | null | A major goal of developing high-precision control of many-body quantum
systems is to realise their potential as quantum computers. Probably the most
significant obstacle in this direction is the problem of "decoherence": the
extreme fragility of quantum systems to environmental noise and other control
limitations. The theory of fault-tolerant quantum error correction has shown
that quantum computation is possible even in the presence of decoherence
provided that the noise affecting the quantum system satisfies certain
well-defined theoretical conditions. However, existing methods for noise
characterisation have become intractable already for the systems that are
controlled in today's labs. In this paper we introduce a technique based on
symmetrisation that enables direct experimental characterisation of key
properties of the decoherence affecting a multi-body quantum system. Our method
reduces the number of experiments required by existing methods from exponential
to polynomial in the number of subsystems. We demonstrate the application of
this technique to the optimisation of control over nuclear spins in the solid
state.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 19:55:30 GMT"
}
] | 2007-10-30T00:00:00 | [
[
"Emerson",
"Joseph",
""
],
[
"Silva",
"Marcus",
""
],
[
"Moussa",
"Osama",
""
],
[
"Ryan",
"Colm",
""
],
[
"Laforest",
"Martin",
""
],
[
"Baugh",
"Jonathan",
""
],
[
"Cory",
"David G.",
""
],
[
"Laflamme",
"Raymond",
""
]
] |
0707.0686 | Luc Bouten | Luc Bouten and Andrew Silberfarb | Adiabatic elimination in quantum stochastic models | 17 pages, no figures, corrected mistakes | Commun. Math. Phys. 283, 491-505 (2008) | 10.1007/s00220-008-0513-6 | null | math-ph math.MP quant-ph | null | We consider a physical system with a coupling to bosonic reservoirs via a
quantum stochastic differential equation. We study the limit of this model as
the coupling strength tends to infinity. We show that in this limit the
solution to the quantum stochastic differential equation converges strongly to
the solution of a limit quantum stochastic differential equation. In the
limiting dynamics the excited states are removed and the ground states couple
directly to the reservoirs.
| [
{
"version": "v1",
"created": "Thu, 5 Jul 2007 10:38:38 GMT"
},
{
"version": "v2",
"created": "Wed, 22 Aug 2007 23:13:04 GMT"
},
{
"version": "v3",
"created": "Tue, 2 Oct 2007 21:40:44 GMT"
},
{
"version": "v4",
"created": "Thu, 6 Dec 2007 20:27:31 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Bouten",
"Luc",
""
],
[
"Silberfarb",
"Andrew",
""
]
] |
0707.0687 | Moshe Gai | Moshe Gai (Yale and UConn-LNS at Avery Point) | The Dissociation of 8B in the Coulomb Field and the Validity of the CD
Method | Invited Talk, Spring Seminar on Nuclear Physics, May 20 - 24, 2007,
Vico Equense, Italy. Work Supported by USDOE grant No. DE-FG02-94ER40870 | null | 10.1142/9789812779038_0059 | null | nucl-ex astro-ph nucl-th | null | The GSI1, GSI2 (as well as the RIKEN2 and the corrected GSI2) measurements of
the Coulomb Dissociation (CD) of 8B are in good agreement with the most recent
Direct Capture (DC) 7Be(p,g)8B reaction measurement performed at Weizmann and
in agreement with the Seattle result. Yet it was claimed that the CD and DC
results are sufficiently different and need to be reconciled. We show that
these statements arise from a misunderstanding (as well as misrepresentation)
of CD experiments. We recall a similar strong statement questioning the
validity of the CD method due to an invoked large E2 component that was also
shown to arise from a misunderstanding of the CD method. In spite of the good
agreement between DC and CD data the slope of the astrophysical cross section
factor (S17) can not be extracted with high accuracy due to a discrepancy
between the recent DC data as well as a discrepancy of the three reports of the
GSI CD data. The slope is directly related to the d-wave component that
dominates at higher energies and must be subtracted from measured data to
extrapolate to zero energy. Hence the uncertainty of the measured slope leads
to an additional uncertainty of the extrapolated zero energy cross section
factor, S17(0). This uncertainty must be alleviated by future experiments to
allow a precise determination of S17(0), a goal that so far has not be achieved
in spite of strong statement(s) that appeared in the literature.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 20:20:33 GMT"
}
] | 2017-08-23T00:00:00 | [
[
"Gai",
"Moshe",
"",
"Yale and UConn-LNS at Avery Point"
]
] |
0707.0688 | Samarth Chandra | Samarth Chandra | Dependence of ground state energy of classical n-vector spins on n | 6 pages, 2 figures, submitted to Physical Review E | null | 10.1103/PhysRevE.77.021125 | null | cond-mat.stat-mech | null | We study the ground state energy E_G(n) of N classical n-vector spins with
the hamiltonian H = - \sum_{i>j} J_ij S_i.S_j where S_i and S_j are n-vectors
and the coupling constants J_ij are arbitrary. We prove that E_G(n) is
independent of n for all n > n_{max}(N) = floor((sqrt(8N+1)-1) / 2) . We show
that this bound is the best possible. We also derive an upper bound for E_G(m)
in terms of E_G(n), for m<n. We obtain an upper bound on the frustration in the
system, as measured by F(n), which is defined to be (\sum_{i>j} |J_ij| +
E_G(n)) / (\sum_{i>j} |J_ij|). We describe a procedure for constructing a set
of J_ij's such that an arbitrary given state, {S_i}, is the ground state.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 20:54:47 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Chandra",
"Samarth",
""
]
] |
0707.0689 | Gabriele Ghisellini | G. Ghisellini, G. Ghirlanda, F. Tavecchio (INAF-Osservatorio
Astronomico di Brera) | Did we observe the supernova shock breakout in GRB 060218? | 5 pages, 2 figures, revised version, MNRAS Letters, in press | null | 10.1111/j.1745-3933.2007.00396.x | null | astro-ph | null | If the early optical data of GRB 060218 up to 1e5 s are interpreted as the
black-body flux associated with the supernova shock breakout, we can derive
lower limits to the bolometric luminosity and energetics of this black-body
component. These limits are more severe for the very early data that imply
energetics of order of 1e51 erg. These values, puzzlingly large, are rather
independent of the assumed time profile of the emitting surface, provided that
the corresponding radius does not increase superluminally. Another concern is
the luminosity of the black-body component observed in the X-rays, that is
large and appears to be produced by an approximately constant temperature and a
surface area increasing only slowly in time. Although it has been suggested
that the long X-ray black-body duration is consistent with the supernova shock
breakout if anisotropy is assumed, the nearly constant emitting surface
requires some fine tuning, allowing and suggesting an alternative
interpretation, i.e. emission from late dissipation of the fireball bulk
kinetic energy. This in turn requires a small value of the bulk Lorentz factor.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 20:00:35 GMT"
},
{
"version": "v2",
"created": "Mon, 17 Sep 2007 08:24:31 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Ghisellini",
"G.",
"",
"INAF-Osservatorio\n Astronomico di Brera"
],
[
"Ghirlanda",
"G.",
"",
"INAF-Osservatorio\n Astronomico di Brera"
],
[
"Tavecchio",
"F.",
"",
"INAF-Osservatorio\n Astronomico di Brera"
]
] |
0707.0690 | Jos\'e Prieto | Jose L. Prieto, Krzysztof Z. Stanek, John F. Beacom (Ohio State) | Characterizing Supernova Progenitors via the Metallicities of their Host
Galaxies, from Poor Dwarfs to Rich Spirals | ApJ accepted, 26 pages, 5 figures, 1 table. Updated catalogs are
available at http://www.astronomy.ohio-state.edu/~prieto/snhosts/ | Astrophys.J.673:999-1008,2008 | 10.1086/524654 | null | astro-ph | null | We investigate how the different types of supernovae are relatively affected
by the metallicity of their host galaxy. We match the SAI Supernova Catalog to
the SDSS-DR4 catalog of star-forming galaxies with measured metallicities.
These supernova host galaxies span a range of oxygen abundance from 12 +
log(O/H) = 7.9 to 9.3 (~ 0.1 to 2.7 solar) and a range in absolute magnitude
from MB = -15.2 to -22.2. To reduce the various observational biases, we select
a subsample of well-characterized supernovae in the redshift range from 0.01 to
0.04, which leaves us with 58 SN II, 19 Ib/c, and 38 Ia. We find strong
evidence that SN Ib/c are occurring in higher-metallicity host galaxies than SN
II, while we see no effect for SN Ia relative to SN II. We note some extreme
and interesting supernova-host pairs, including the metal-poor (~ 1/4 solar)
host of the recent SN Ia 2007bk, where the supernova was found well outside of
this dwarf galaxy. To extend the luminosity range of supernova hosts to even
fainter galaxies, we also match all the historical supernovae with z < 0.3 to
the SDSS-DR6 sky images, resulting in 1225 matches. This allows us to identify
some even more extreme cases, such as the recent SN Ic 2007bg, where the likely
host of this hypernova-like event has an absolute magnitude MB ~ -12, making it
one of the least-luminous supernova hosts ever observed. This low-luminosity
host is certain to be very metal poor (~ 1/20 solar), and therefore this
supernova is an excellent candidate for association with an off-axis GRB. The
two catalogs that we have constructed are available online and will be updated
regularly. Finally, we discuss various implications of our findings for
understanding supernova progenitors and their host galaxies.
| [
{
"version": "v1",
"created": "Thu, 5 Jul 2007 16:22:48 GMT"
},
{
"version": "v2",
"created": "Wed, 17 Oct 2007 19:04:16 GMT"
}
] | 2010-11-11T00:00:00 | [
[
"Prieto",
"Jose L.",
"",
"Ohio State"
],
[
"Stanek",
"Krzysztof Z.",
"",
"Ohio State"
],
[
"Beacom",
"John F.",
"",
"Ohio State"
]
] |
0707.0691 | Fr\'ed\'eric Dupuis | Simon Pierre Desrosiers and Fr\'ed\'eric Dupuis | Quantum entropic security and approximate quantum encryption | Corrected mistakes in the proofs of Theorems 3 and 6; results
unchanged. To appear in IEEE Transactions on Information Theory. | null | 10.1109/TIT.2010.2048488 | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We present full generalisations of entropic security and entropic
indistinguishability to the quantum world where no assumption but a limit on
the knowledge of the adversary is made. This limit is quantified using the
quantum conditional min-entropy as introduced by Renato Renner. A proof of the
equivalence between the two security definitions is presented. We also provide
proofs of security for two different cyphers in this model and a proof for a
lower bound on the key length required by any such cypher. These cyphers
generalise existing schemes for approximate quantum encryption to the entropic
security model.
| [
{
"version": "v1",
"created": "Thu, 5 Jul 2007 13:53:22 GMT"
},
{
"version": "v2",
"created": "Thu, 15 Apr 2010 13:06:10 GMT"
}
] | 2010-04-16T00:00:00 | [
[
"Desrosiers",
"Simon Pierre",
""
],
[
"Dupuis",
"Frédéric",
""
]
] |
0707.0692 | Sergei Bashinsky | Sergei Bashinsky (Los Alamos) | Mapping Cosmological Observables to the Dark Kinetics | 20 pages, 6 figures, submitted to ApJ | null | null | LA-UR-07-2136 | astro-ph gr-qc hep-ph hep-th | null | We study systematically which features in the cosmic microwave background
(CMB) and large-scale structure (LSS) probe various inhomogeneous properties of
the dark sectors (including neutrinos, dark matter, and dark energy). We
stress, and quantify by simple formulas, that the primary CMB anisotropies are
very susceptible to the gravitational potentials during horizon entry, less at
recombination. The CMB thus allows us to scan \Phi+\Psi and the underlying dark
kinetics for all redshifts z~1-10^5. LSS, on the other hand, responds strongest
to \Phi at low redshifts. Dark perturbations are often parameterized by the
anisotropic stress and effective sound speed (stiffness). We find that the dark
anisotropic stress and stiffness influence the visible species at the
correspondingly early and late stages of horizon entry, and affect stronger
respectively the CMB and LSS. The CMB yet remains essential to probing the
stiff perturbations of light neutrinos and dark energy, detectable only during
horizon entry. The clustering of dark species and large propagation speed of
their inhomogeneities also map to distinctive features in the CMB and LSS. -Any
parameterization of the signatures of dark kinetics that assumes general
relativity can effectively accommodate any modified gravity (MG) that retains
the equivalence principle for the visible sectors. This implies that formally
the nonstandard structure growth or \Phi/\Psi ratio, while indicative, are not
definitive MG signatures. The definitive signatures of MG may include the
strong dependence of the apparent dark dynamics on visible species, its
superluminality, and the nonstandard phenomenology of gravitational waves.
| [
{
"version": "v1",
"created": "Thu, 5 Jul 2007 18:49:06 GMT"
}
] | 2007-07-11T00:00:00 | [
[
"Bashinsky",
"Sergei",
"",
"Los Alamos"
]
] |
0707.0693 | John Grimes | J. P. Grimes, T. Heckman, D. Strickland, W. V. Dixon, K. Sembach, R.
Overzier, C. Hoopes, A. Aloisi, and A. Ptak | Feedback in the local LBG Analog Haro 11 as probed by far-UV and X-ray
observations | Accepted for publication in ApJ, 40 pages, 17 figures | null | 10.1086/521353 | null | astro-ph | null | We have re-analyzed FUSE data and obtained new Chandra observations of Haro
11, a local (D_L=88 Mpc) UV luminous galaxy. Haro 11 has a similar far-UV
luminosity (10^10.3 L_\odot), UV surface brightness (10^9.4 L_\odot kpc^-2),
SFR, and metallicity to that observed in Lyman Break Galaxies (LBGs). We show
that Haro 11 has extended, soft thermal (kT~0.68 keV) X-ray emission with a
luminosity and size which scales with the physical properties (e.g. SFR,
stellar mass) of the host galaxy. An enhanced alpha/Fe, ratio of ~4 relative to
solar abundance suggests significant supernovae enrichment. These results are
consistent with the X-ray emission being produced in a shock between a
supernovae driven outflow and the ambient material. The FUV spectra show strong
absorption lines similar to those observed in LBG spectra. A blueshifted
absorption component is identified as a wind outflowing at ~200-280 km/s.
OVI\lambda\lambda1032,1038 emission, the dominant cooling mechanism for coronal
gas at T~10^5.5 K is also observed. If associated with the outflow, the
luminosity of the OVI emission suggests that <20% of the total mechanical
energy from the supernovae and solar winds is being radiated away. This implies
that radiative cooling through OVI is not significantly inhibiting the growth
of the outflowing gas. In contradiction to the findings of Bergvall et al 2006,
we find no convincing evidence of Lyman continuum leakage in Haro 11. We
conclude that the wind has not created a `tunnel' allowing the escape of a
significant fraction of Lyman continuum photons and place a limit on the escape
fraction of f_{esc}<2%. Overall, both Haro 11 and a previously observed LBG
analogue VV 114, provide an invaluable insight into the X-ray and FUV
properties of high redshift LBGs.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 20:09:35 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Grimes",
"J. P.",
""
],
[
"Heckman",
"T.",
""
],
[
"Strickland",
"D.",
""
],
[
"Dixon",
"W. V.",
""
],
[
"Sembach",
"K.",
""
],
[
"Overzier",
"R.",
""
],
[
"Hoopes",
"C.",
""
],
[
"Aloisi",
"A.",
""
],
[
"Ptak",
"A.",
""
]
] |
0707.0694 | Yakiv Pavlenko V. | Ya.V.Pavlenko (UH, MAO NASU), H.R.A.Jones (UH), E.L.Martin (IAC, Univ.
Centr. Florida), E.Guenther (Turinger Sternwarte), M.A. Kenworthy (CAAO),
M.R.Zapatero Osorio (IAC) | Lithium in LP 944-20 | 14 pages, 17 figs, accepted by MNRAS (upgraded version) | null | 10.1111/j.1365-2966.2007.12182.x | null | astro-ph | null | We present a new estimate of the lithium abundance in the atmosphere of the
brown dwarf LP 944-20. Our analysis is based on a self-consistent analysis of
low, intermediate and high resolution optical and near-infrared spectra. We
obtain log N(Li) = 3.25 +/-0.25 using fits of our synthetic spectra to the Li I
resonance line doublet profiles observed with VLT/UVES and AAT/SPIRAL. This
lithium abundance is over two orders of magnitude larger than previous
estimates in the literature. In order to obtain good fits of the resonance
lines of K I and Rb I and better fits to the TiO molecular absorption around
the Li I resonance line, we invoke a semi-empirical model atmosphere with the
dusty clouds located above the photosphere. The lithium abundance, however, is
not changed by the effects of the dusty clouds. We discuss the implications of
our estimate of the lithium abundance in LP 944-20 for the understanding of the
properties of this benchmark brown dwarf.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 20:12:22 GMT"
},
{
"version": "v2",
"created": "Sat, 14 Jul 2007 19:01:23 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Pavlenko",
"Ya. V.",
"",
"UH, MAO NASU"
],
[
"Jones",
"H. R. A.",
"",
"UH"
],
[
"Martin",
"E. L.",
"",
"IAC, Univ.\n Centr. Florida"
],
[
"Guenther",
"E.",
"",
"Turinger Sternwarte"
],
[
"Kenworthy",
"M. A.",
"",
"CAAO"
],
[
"Osorio",
"M. R. Zapatero",
"",
"IAC"
]
] |
0707.0695 | Daniel Podolsky | Daniel Podolsky, Shailesh Chandrasekharan, and Ashvin Vishwanath | Phase Transitions of S=1 Spinor Condensates in an Optical Lattice | 9 pages, 7 figures; v4 - Expanded manuscript | Phys. Rev. B 80, 214513 (2009) | 10.1103/PhysRevB.80.214513 | null | cond-mat.stat-mech cond-mat.str-el hep-lat | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the phase diagram of spin-one polar condensates in a two dimensional
optical lattice with magnetic anisotropy. We show that the topological binding
of vorticity to nematic disclinations allows for a rich variety of phase
transitions. These include Kosterlitz-Thouless-like transitions with a
superfluid stiffness jump that can be experimentally tuned to take a continuous
set of values, and a new cascaded Kosterlitz-Thouless transition, characterized
by two divergent length scales. For higher integer spin bosons S, the thermal
phase transition out of the planar polar phase is strongly affected by the
parity of S.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 20:48:16 GMT"
},
{
"version": "v2",
"created": "Tue, 18 Nov 2008 18:51:05 GMT"
},
{
"version": "v3",
"created": "Thu, 3 Sep 2009 15:56:47 GMT"
},
{
"version": "v4",
"created": "Wed, 4 Nov 2009 16:10:40 GMT"
}
] | 2013-05-29T00:00:00 | [
[
"Podolsky",
"Daniel",
""
],
[
"Chandrasekharan",
"Shailesh",
""
],
[
"Vishwanath",
"Ashvin",
""
]
] |
0707.0696 | Vasilisa Shramchenko | Vasilisa Shramchenko | Riemann-Hilbert problem associated to Frobenius manifold structures on
Hurwitz spaces: irregular singularity | 41 page, 11 figures | Duke Math. J. 144, no. 1, 1-52 (2008) | null | null | math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Solutions to the Riemann-Hilbert problems with irregular singularities
naturally associated to semisimple Frobenius manifold structures on Hurwitz
spaces (moduli spaces of meromorphic functions on Riemann surfaces) are
constructed. The solutions are given in terms of meromorphic bidifferentials
defined on the underlying Riemann surface. The relationship between different
classes of Frobenius manifold structures on Hurwitz spaces (real doubles,
deformations) is described on the level of the corresponding Riemann-Hilbert
problems.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 20:19:39 GMT"
},
{
"version": "v2",
"created": "Mon, 22 Sep 2008 19:42:30 GMT"
}
] | 2008-09-22T00:00:00 | [
[
"Shramchenko",
"Vasilisa",
""
]
] |
0707.0697 | Evgueni Goudzovski | J.R. Batley, et al | Search for direct CP violating charge asymmetries in
$K^\pm\to\pi^\pm\pi^+\pi^-$ and $K^\pm\to\pi^\pm\pi^0\pi^0$ decays | 29 pages, 9 figures. An updated version accepted by the EPJC | Eur.Phys.J.C52:875-891,2007 | 10.1140/epjc/s10052-007-0456-7 | CERN-PH-EP/2007-021 | hep-ex | null | A measurement of the direct CP violating charge asymmetries of the Dalitz
plot linear slopes $A_g=(g^+-g^-)/(g^++g^-)$ in $K^\pm\to\pi^\pm\pi^+\pi^-$ and
$K^\pm\to\pi^\pm\pi^0\pi^0$ decays by the NA48/2 experiment at CERN SPS is
presented. A new technique of asymmetry measurement involving simultaneous
$K^+$ and $K^-$ beams and a large data sample collected allowed a result of an
unprecedented precision. The charge asymmetries were measured to be
$A^c_g=(-1.5\pm2.2)\times10^{-4}$ with $3.11\times 10^9$
$K^{\pm}\to\pi^\pm\pi^+\pi^-$ decays, and $A^n_g=(1.8\pm1.8)\times10^{-4}$ with
$9.13\times 10^7$ $K^{\pm}\to\pi^\pm\pi^0\pi^0$ decays. The precision of the
results is limited mainly by the size of the data sample.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 21:37:23 GMT"
},
{
"version": "v2",
"created": "Wed, 17 Oct 2007 13:16:52 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Batley",
"J. R.",
""
]
] |
0707.0698 | Hans Vernaeve | Hans Vernaeve | Ideals in the ring of Colombeau generalized numbers | null | Comm. Alg. (2010) 38 (6): 2199-2228 | null | null | math.RA | null | In this paper, the structure of the ideals in the ring of Colombeau
generalized numbers is investigated. Connections with the theories of exchange
rings, Gelfand rings and lattice-ordered rings are given. Characterizations for
prime, projective, pure and topologically closed ideals are given, answering in
particular the questions about prime ideals in [Aragona-Juriaans]. Also
z-ideals in the sense of [Mason] are characterized. The quotient rings modulo
maximal ideals are shown to be canonically isomorphic with nonstandard fields
of asymptotic numbers. Finally, a detailed study of the ideals allows us to
prove that (under some set-theoretic assumption) the Hahn-Banach extension
property does not hold for a large class of topological modules over the ring
of Colombeau generalized numbers.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 21:20:22 GMT"
}
] | 2014-04-01T00:00:00 | [
[
"Vernaeve",
"Hans",
""
]
] |
0707.0699 | Jordan Bell | Leonhard Euler | A double demonstration of a theorem of Newton, which gives a relation
between the coefficient of an algebraic equation and the sums of the powers
of its roots | 9 pages | null | null | null | math.HO math.CA math.GM | null | Translation from the Latin original, "Demonstratio gemina theorematis
Neutoniani, quo traditur relatio inter coefficientes cuiusvis aequationis
algebraicae et summas potestatum radicum eiusdem" (1747). E153 in the Enestrom
index. In this paper Euler gives two proofs of Newton's identities, which
express the sums of powers of the roots of a polynomial in terms of its
coefficients. The first proof takes the derivative of a logarithm. The second
proof uses induction and the fact that in a polynomial of degree $n$, the
coefficient of $x^{n-k}$ is equal to the sum of the products of $k$ roots,
times $(-1)^k$.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 21:37:45 GMT"
}
] | 2007-07-06T00:00:00 | [
[
"Euler",
"Leonhard",
""
]
] |
0707.0700 | Joao Strapasson E | Jos\'e C. Cifuente, Jo\~ao E. Strapasson, Ana C. Corr\^ea and
Patr\'icia M. Kitani | The Ring of Integers in the Canonical Structures of the Planes | 9 pages | null | null | null | math.RA math.AC | null | The \emph{canonical structures of the plane} are those that result, up to
isomorphism, from the rings that have the form $\mathds{R}[x]/(ax^2+bx+c)$ with
$a\neq 0$.That ring is isomorphic to $\mathds{R}[\theta]$, where $\theta$ is
the equivalence class of x, which satisfies $\theta^2 = (-\dfrac{c}{a}) +
\theta (-\dfrac{b}{a})$. On the other hand, it is known that, up to
isomorphism, there are only three canonical structures: the corresponding to
$\theta^2 = -1$ (the complex numbers), $\theta^2 = 1$ (the perplex or
hyperbolic numbers) and $\theta^2 = 0$ (the parabolic numbers). This article
copes with the algebraic structure of the rings of integers
$\mathds{Z}[\theta]$ in the perplex and parabolic cases by \emph{analogy} to
the complex cases: the ring of Gaussian integers. For those rings a
\emph{division algorithm} is proved and it is obtained, as a consequence, the
characterization of the prime and irreducible elements.
| [
{
"version": "v1",
"created": "Thu, 5 Jul 2007 14:48:29 GMT"
}
] | 2007-07-06T00:00:00 | [
[
"Cifuente",
"José C.",
""
],
[
"Strapasson",
"João E.",
""
],
[
"Corrêa",
"Ana C.",
""
],
[
"Kitani",
"Patrícia M.",
""
]
] |
0707.0701 | Alexandre d'Aspremont | Ronny Luss, Alexandre d'Aspremont | Clustering and Feature Selection using Sparse Principal Component
Analysis | More experiments | null | null | null | cs.AI cs.LG cs.MS | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | In this paper, we study the application of sparse principal component
analysis (PCA) to clustering and feature selection problems. Sparse PCA seeks
sparse factors, or linear combinations of the data variables, explaining a
maximum amount of variance in the data while having only a limited number of
nonzero coefficients. PCA is often used as a simple clustering technique and
sparse factors allow us here to interpret the clusters in terms of a reduced
set of variables. We begin with a brief introduction and motivation on sparse
PCA and detail our implementation of the algorithm in d'Aspremont et al.
(2005). We then apply these results to some classic clustering and feature
selection problems arising in biology.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 21:53:11 GMT"
},
{
"version": "v2",
"created": "Wed, 8 Oct 2008 18:41:53 GMT"
}
] | 2008-10-08T00:00:00 | [
[
"Luss",
"Ronny",
""
],
[
"d'Aspremont",
"Alexandre",
""
]
] |
0707.0702 | Alex Lazarian | Alex Lazarian | Diffusion Processes in Turbulent Magnetic Fields | 3 figures, 11 pages, to be published in AIP volume of "Turbulence and
Non-linear Processes in Astrophysical Plasmas" | AIPConf.Proc.932:58-68,2007 | 10.1063/1.2778946 | null | astro-ph | null | We study of the effect of turbulence on diffusion processes within magnetized
medium. While we exemplify our treatment with heat transfer processes, our
results are quite general and are applicable to different processes, e.g.
diffusion of heavy elements. Our treatment is also applicable to describing the
diffusion of cosmic rays arising from magnetic field wandering. In particular,
we find that when the energy injection velocity is smaller than the Alfven
speed the heat transfer is partially suppressed, while in the opposite regime
the effects of turbulence depend on the intensity of driving. In fact, the
scale $l_A$ at which the turbulent velocity is equal the Alfven velocity is a
new important parameter. When the electron mean free path $\lambda$ is larger
than $l_A$, the stronger the the turbulence, the lower thermal conductivity by
electrons is. The turbulent motions, however, induces their own advective
transport, that can provide effective diffusivity. For clusters of galaxies, we
find that the turbulence is the most important agent for heat transfer. We also
show that the domain of applicability of the subdiffusion concept is rather
limited.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 21:58:24 GMT"
},
{
"version": "v2",
"created": "Thu, 5 Jul 2007 20:50:16 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Lazarian",
"Alex",
""
]
] |
0707.0703 | Julian Milano | J. Milano, L. B. Steren, A. H. V. Repetto Llamazares, V. Garcia, M.
Marangolo, M. Eddrief, V. H. Etgens | Detection of the magneto-structural phase coexistence in MnAs epilayers
at a very early stage | 8 pages, 5 figures | Applied Physics Letters Volume 92, Issue 3, 2008, Article number
032503 | 10.1063/1.2837178 | null | cond-mat.mtrl-sci | null | We report on the appearance of magnetic stripes in MnAs/GaAs(100) epilayers
at temperatures well below the ferromagnetic transition of the system. The
study has been performed by ferromagnetic resonance experiments (FMR) on MnAs
epilayers grown on (100) and (111) GaAs substrates. The FMR spectra of the
MnAs/GaAs(100) samples at 180 K reveal the appearance of zones of different
magnetic behavior with respect to the low-temperature homogeneous ferromagnetic
phase. The angular and the temperature dependence of the spectra serve us to
detect the inter-growth of the non-magnetic phase into the ferromagnetic phase
at a very early stage of the process. The experimental data show that the new
phase nucleates in a self-arranged array of stripes in MnAs/GaAs(100) thin
films while it grows randomly in the same films grown on GaAs(111).
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 22:09:34 GMT"
}
] | 2014-02-26T00:00:00 | [
[
"Milano",
"J.",
""
],
[
"Steren",
"L. B.",
""
],
[
"Llamazares",
"A. H. V. Repetto",
""
],
[
"Garcia",
"V.",
""
],
[
"Marangolo",
"M.",
""
],
[
"Eddrief",
"M.",
""
],
[
"Etgens",
"V. H.",
""
]
] |
0707.0704 | Alexandre d'Aspremont | Onureena Banerjee, Laurent El Ghaoui, Alexandre d'Aspremont | Model Selection Through Sparse Maximum Likelihood Estimation | null | null | null | null | cs.AI cs.LG | null | We consider the problem of estimating the parameters of a Gaussian or binary
distribution in such a way that the resulting undirected graphical model is
sparse. Our approach is to solve a maximum likelihood problem with an added
l_1-norm penalty term. The problem as formulated is convex but the memory
requirements and complexity of existing interior point methods are prohibitive
for problems with more than tens of nodes. We present two new algorithms for
solving problems with at least a thousand nodes in the Gaussian case. Our first
algorithm uses block coordinate descent, and can be interpreted as recursive
l_1-norm penalized regression. Our second algorithm, based on Nesterov's first
order method, yields a complexity estimate with a better dependence on problem
size than existing interior point methods. Using a log determinant relaxation
of the log partition function (Wainwright & Jordan (2006)), we show that these
same algorithms can be used to solve an approximate sparse maximum likelihood
problem for the binary case. We test our algorithms on synthetic data, as well
as on gene expression and senate voting records data.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 22:13:42 GMT"
}
] | 2007-07-06T00:00:00 | [
[
"Banerjee",
"Onureena",
""
],
[
"Ghaoui",
"Laurent El",
""
],
[
"d'Aspremont",
"Alexandre",
""
]
] |
0707.0705 | Alexandre d'Aspremont | Alexandre d'Aspremont, Francis Bach, Laurent El Ghaoui | Optimal Solutions for Sparse Principal Component Analysis | Revised journal version. More efficient optimality conditions and new
examples in subset selection and sparse recovery. Original version is in ICML
proceedings | null | null | null | cs.AI cs.LG | null | Given a sample covariance matrix, we examine the problem of maximizing the
variance explained by a linear combination of the input variables while
constraining the number of nonzero coefficients in this combination. This is
known as sparse principal component analysis and has a wide array of
applications in machine learning and engineering. We formulate a new
semidefinite relaxation to this problem and derive a greedy algorithm that
computes a full set of good solutions for all target numbers of non zero
coefficients, with total complexity O(n^3), where n is the number of variables.
We then use the same relaxation to derive sufficient conditions for global
optimality of a solution, which can be tested in O(n^3) per pattern. We discuss
applications in subset selection and sparse recovery and show on artificial
examples and biological data that our algorithm does provide globally optimal
solutions in many cases.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 22:28:28 GMT"
},
{
"version": "v2",
"created": "Fri, 3 Aug 2007 22:30:22 GMT"
},
{
"version": "v3",
"created": "Fri, 24 Aug 2007 00:49:31 GMT"
},
{
"version": "v4",
"created": "Fri, 9 Nov 2007 17:27:11 GMT"
}
] | 2011-11-10T00:00:00 | [
[
"d'Aspremont",
"Alexandre",
""
],
[
"Bach",
"Francis",
""
],
[
"Ghaoui",
"Laurent El",
""
]
] |
0707.0706 | Owen Pavel Fernandez Piedra | Owen Pavel Fernandez Piedra and Alejandro Cabo Montes de Oca | Quantization of massive scalar fields over static black string
backgrounds | 4 pages | Phys.Rev.D75:107501,2007 | 10.1103/PhysRevD.75.107501 | null | gr-qc | null | The renormalized mean value of the corresponding components of the
Energy-Momentum tensor for massive scalar fields coupled to an arbitrary
gravitational field configuration having cylindrical symmetry are analytically
evaluated using the Schwinger-DeWitt approximation, up to second order in the
inverse mass value. The general results are employed to explicitly derive
compact analytical expressions for the Energy-Momentum tensor in the particular
background of the Black-String spacetime. In the case of the Black String
considered in this work, we proof that a violation of the weak energy condition
occur at the horizon of the space-time for values of the coupling constant,
that include as particular cases the most interesting of minimal and conformal
coupling.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 22:37:56 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Piedra",
"Owen Pavel Fernandez",
""
],
[
"de Oca",
"Alejandro Cabo Montes",
""
]
] |
0707.0707 | Andreas Heider | Andreas Heider | Two results from Morita theory of stable model categories | 69 pages | null | null | null | math.AT | null | We prove two results from Morita theory of stable model categories. Both can
be regarded as topological versions of recent algebraic theorems. One is on
recollements of triangulated categories, which have been studied in the
algebraic case by J{\o}rgensen. We give a criterion which answers the following
question: When is there a recollement for the derived category of a given
symmetric ring spectrum in terms of two other symmetric ring spectra? The other
result is on well generated triangulated categories in the sense of Neeman.
Porta characterizes the algebraic well generated categories as localizations of
derived categories of DG categories. We prove a topological analogon: a
topological triangulated category is well generated if and only if it is
triangulated equivalent to a localization of the derived category of a
symmetric ring spectrum with several objects. Here `topological' means
triangulated equivalent to the homotopy category of a spectral model category.
Moreover, we show that every well generated spectral model category is Quillen
equivalent to a Bousfield localization of a category of modules via a single
Quillen functor.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 23:00:17 GMT"
}
] | 2007-07-06T00:00:00 | [
[
"Heider",
"Andreas",
""
]
] |
0707.0708 | Owen Pavel Fernandez Piedra | Owen Pavel Fernandez Piedra and Alejandro Cabo Montes de Oca | Vacuum polarization of massive spinor fields in static black-string
backgrounds | 15 pages, few corrections are done in this version | Phys.Rev.D77:024044,2008 | 10.1103/PhysRevD.77.024044 | null | gr-qc | null | The renormalized mean value of the quantum Lagrangian and the corresponding
components of the Energy-Momentum tensor for massive spinor fields coupled to
an arbitrary gravitational field configuration having cylindrical symmetry are
analytically evaluated using the Schwinger-DeWitt approximation, up to second
order in the inverse mass value. The general results are employed to explicitly
derive compact analytical expressions for the quantum mean Lagrangian and
Energy- Momentum tensor in the particular background of the Black-String
space-time.
| [
{
"version": "v1",
"created": "Wed, 4 Jul 2007 22:55:23 GMT"
},
{
"version": "v2",
"created": "Sun, 2 Sep 2007 15:54:02 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Piedra",
"Owen Pavel Fernandez",
""
],
[
"de Oca",
"Alejandro Cabo Montes",
""
]
] |
0707.0709 | Shai Ronen | Shai Ronen and John Bohn | Dipolar Bose-Einstein condensates at Finite temperature | 9 figures | null | 10.1103/PhysRevA.76.043607 | null | cond-mat.stat-mech | null | We study a Bose-Einstein condensate (BEC) of a dilute gas with dipolar
interactions, at finite temperature, using the Hartree-Fock-Bogoliubov (HFB)
theory within the Popov approximation. An additional approximation involving
the dipolar exchange interaction is made to facilitate the computation. We
calculate the temperature dependence of the condensate fraction of a condensate
confined in a cylindrically symmetric harmonic trap. We show that the
bi-concave shaped condensates found in Ref. \cite{Ronen07} in certain pancake
traps at zero temperature, are also stable at finite temperature. Surprisingly,
the dip in the central density of these structured condensates is actually
enhanced at low finite temperatures. We explain this effect.
| [
{
"version": "v1",
"created": "Thu, 5 Jul 2007 00:16:23 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Ronen",
"Shai",
""
],
[
"Bohn",
"John",
""
]
] |
0707.0710 | Gargi Chaudhuri | G. Chaudhuri, S. Das Gupta, W. G. Lynch, M. Mocko, and M. B. Tsang | Cross-sections of neutron rich nuclei from projectile fragmentation:
canonical thermodynamic model estimates | 10 pages, 4 figures | Phys.Rev.C76:067601,2007 | 10.1103/PhysRevC.76.067601 | null | nucl-th | null | A remarkably simple dependence of fragmentation cross-section on average
binding energy has been established in experimental data. This dependence was
empirically parametrised leading to a very useful formula for extrapolation. We
find that the canonical thermodynamic model, which has been used in the past
for successful computations of many observables resulting from
multifragmentation, reproduces the salient fetures of fragmentation
cross-sections of very neutron rich nuclei very well. This helps towards a
theoretical understanding of the observed data.
| [
{
"version": "v1",
"created": "Thu, 5 Jul 2007 01:13:08 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Chaudhuri",
"G.",
""
],
[
"Gupta",
"S. Das",
""
],
[
"Lynch",
"W. G.",
""
],
[
"Mocko",
"M.",
""
],
[
"Tsang",
"M. B.",
""
]
] |
0707.0711 | Ilya Mandel | Ilya Mandel | Spin distribution following minor mergers and the effect of spin on the
detection range for low-mass-ratio inspirals | 18 pages, 5 figures | null | null | null | astro-ph gr-qc | null | We compute the probability distribution for the spin of a black hole
following a series of minor mergers with isotropically distributed,
non-spinning, inspiraling compact objects. By solving the Fokker-Planck
equation governing this stochastic process, we obtain accurate analytical fits
for the evolution of the mean and standard deviation of the spin distribution
in several parameter regimes. We complement these analytical fits with
numerical Monte-Carlo simulations in situations when the Fokker-Planck analysis
is not applicable. We find that a ~150 solar-mass intermediate-mass black hole
that gained half of its mass through minor mergers with neutron stars will have
dimensionless spin parameter chi=a/M~0.2 \pm 0.08. We estimate the effect of
the spin of the central black hole on the detection range for
intermediate-mass-ratio inspiral (IMRI) detections by Advanced LIGO and
extreme-mass-ratio inspiral(EMRI) detections by LISA. We find that for
realistic black hole spins, the inclination-averaged Advanced-LIGO IMRI
detection range may be increased by up to 10% relative to the range for IMRIs
into non-spinning intermediate-mass black holes. For LISA, we find that the
detection range for EMRIs into 10^5 solar-mass massive black holes (MBHs) is
not significantly affected by MBH spin, the range for EMRIs into 10^6
solar-mass MBHs is affected at the ~ 10% level, and EMRIs into maximally
spinning 10^7 solar-mass MBHs are detectable to a distance ~25 times greater
than EMRIs into non-spinning black holes. The resulting bias in favor of
detecting EMRIs into rapidly spinning MBHs will play a role when extracting the
MBH spin distribution from EMRI statistics.
| [
{
"version": "v1",
"created": "Thu, 5 Jul 2007 01:16:07 GMT"
}
] | 2007-07-06T00:00:00 | [
[
"Mandel",
"Ilya",
""
]
] |
0707.0712 | Christopher J. Hillar | Christopher J. Hillar, Charles R. Johnson | On the Positivity of the Coefficients of a Certain Polynomial Defined by
Two Positive Definite Matrices | 7 pages, J. Statistical Physics | null | null | null | math-ph math.MP math.OC | null | It is shown that the polynomial \[p(t) = \text{Tr}[(A+tB)^m]\] has positive
coefficients when $m = 6$ and $A$ and $B$ are any two 3-by-3 complex Hermitian
positive definite matrices. This case is the first that is not covered by
prior, general results. This problem arises from a conjecture raised by Bessis,
Moussa and Villani in connection with a long-standing problem in theoretical
physics. The full conjecture, as shown recently by Lieb and Seiringer, is
equivalent to $p(t)$ having positive coefficients for any $m$ and any two
$n$-by-$n$ positive definite matrices. We show that, generally, the question in
the real case reduces to that of singular $A$ and $B$, and this is a key part
of our proof.
| [
{
"version": "v1",
"created": "Thu, 5 Jul 2007 03:09:22 GMT"
}
] | 2007-07-06T00:00:00 | [
[
"Hillar",
"Christopher J.",
""
],
[
"Johnson",
"Charles R.",
""
]
] |
0707.0713 | Hoshang Heydari | Hoshang Heydari | Algebraic structures of multipartite quantum systems | 7 pages | International Journal of Quantum Information (IJQI), Vol. 6, No. 6
(2008) 1149 - 1154 | null | null | quant-ph | null | We investigate the relation between multilinear mappings and multipartite
states. We show that the isomorphism between multilinear mapping and tensor
product completely characterizes decomposable multipartite states in a
mathematically well-defined manner.
| [
{
"version": "v1",
"created": "Thu, 5 Jul 2007 03:18:47 GMT"
}
] | 2009-01-02T00:00:00 | [
[
"Heydari",
"Hoshang",
""
]
] |
0707.0714 | Israel Quiros | Israel Quiros | Time-like vs Space-like Extra Dimensions | 5 pages, no figures | null | null | null | gr-qc hep-ph | null | Higher-dimensional theories with time-like and space-like extra dimensions
are compared both from the conceptual and from the phenomenological points of
view. In this context causality and unitarity are discussed. It is shown that
additional time-like dimensions allow to recover four-dimensional phenomenology
without invoking neither Kaluza-Klein compactification procedure nor brane
world construct. It is shown, also, that contrary to scenarios with space-like
extra dimensions, in higher-dimensional space-times with additional time-like
dimensions the cosmological constant problem can be safely solved.
| [
{
"version": "v1",
"created": "Thu, 5 Jul 2007 04:30:53 GMT"
}
] | 2007-07-11T00:00:00 | [
[
"Quiros",
"Israel",
""
]
] |
0707.0715 | Neda Zoltan | Robert Deak, Zoltan Neda, Peter B. Barna | An improved kinetic Monte Carlo approach for epitaxial submonolayer
growth | 12 pages, 6 figures | null | null | null | cond-mat.soft cond-mat.mtrl-sci | null | Two-component submonolayer growth on triangular lattice is qualitatively
studied by kinetic Monte Carlo techniques. The hopping barrier governing
surface diffusion of the atoms is estimated with an improved formula and using
realistic pair interaction potentials. Realistic degrees of freedoms enhancing
the surface diffusion of atoms are also introduced. The main advantages of the
presented technique are the reduced number of free parameters and the clear
diffusion activated mechanism for the segregation of different types of atoms.
The potential of this method is exemplified by reproducing (i) vacancy and
stacking fault related phase-boundary creation and dynamics; (ii) a special
co-deposition and segregation process where the segregated atoms of the second
component surrounds the islands formed by the first type of atoms.
| [
{
"version": "v1",
"created": "Thu, 5 Jul 2007 14:48:42 GMT"
}
] | 2007-07-06T00:00:00 | [
[
"Deak",
"Robert",
""
],
[
"Neda",
"Zoltan",
""
],
[
"Barna",
"Peter B.",
""
]
] |
0707.0716 | Jong-Chul Park | Hae Young Cho and Jong-Chul Park | Dynamical $U(1)_R$ Breaking in the Metastable Vacua | 1+13pages, 2figures; references added, minor changes, conclusions
unchanged; Matches published version | JHEP0709:122,2007 | 10.1088/1126-6708/2007/09/122 | null | hep-ph | null | In the Intriligator-Seiberg-Shih model, we parametrize spontaneous breaking
of $U(1)_R$ symmetry with two gauge singlets with R-charges 1 and --1. These
singlets can play the role of the messengers. The messenger scale is
dynamically generated, and hence there is no hierarchy problem between the
supersymmetry breaking scale and the messenger scale. In the gauge mediation
scenario, supersymmetry breaking scale turns out to be around
$\mathcal{O}(10^6)\textrm{GeV}$.
| [
{
"version": "v1",
"created": "Thu, 5 Jul 2007 05:23:08 GMT"
},
{
"version": "v2",
"created": "Tue, 2 Oct 2007 07:12:27 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Cho",
"Hae Young",
""
],
[
"Park",
"Jong-Chul",
""
]
] |
0707.0717 | Jesper Rasmussen | Jesper Rasmussen, Trevor J. Ponman (University of Birmingham, UK) | Temperature and abundance profiles of hot gas in galaxy groups - I.
Results and statistical analysis | 21 pages, 11 figures, accepted for publication in MNRAS | null | 10.1111/j.1365-2966.2007.12191.x | null | astro-ph | null | The distribution of metals in groups of galaxies holds important information
about the chemical enrichment history of the Universe. Here we present radial
profiles of temperature and the abundance of iron and silicon of the hot
intragroup medium for a sample of 15 nearby groups of galaxies observed by
Chandra, selected for their regular X-ray morphology. All but one group display
a cool core, the size of which is found to correlate with the mean temperature
of the group derived outside this core. When scaled to this mean temperature,
the temperature profiles are remarkably similar, being analogous to those of
more massive clusters at large radii but significantly flatter inwards of the
temperature peak. The Fe abundance generally shows a central excess followed by
a radial decline, reaching a typical value of 0.1 solar within r_500, a factor
of two lower than corresponding results for clusters. Si shows less systematic
radial variation, on average displaying a less pronounced decline than Fe and
showing evidence for a flattening at large radii. Off-centre abundance peaks
are seen both for Fe and Si in a number of groups with well-resolved cores.
Derived abundance ratios indicate that supernovae type Ia are responsible for
80 per cent of the Fe in the group core, but the type II contribution increases
with radius and completely dominates at r_500. We present fitting formulae for
the radial dependence of temperature and abundances, to facilitate comparison
to results of numerical simulations of group formation and evolution. In a
companion paper, we discuss the implications of these results for feedback and
enrichment in galaxy groups.
| [
{
"version": "v1",
"created": "Thu, 5 Jul 2007 14:50:53 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Rasmussen",
"Jesper",
"",
"University of Birmingham, UK"
],
[
"Ponman",
"Trevor J.",
"",
"University of Birmingham, UK"
]
] |
0707.0718 | Nils-Peter Skoruppa | Nils-Peter Skoruppa | Jacobi Forms of Critical Weight and Weil Representations | null | null | null | null | math.NT | null | Jacobi forms can be considered as vector valued modular forms, and Jacobi
forms of critical weight correspond to vector valued modular forms of weight
$\frac12$. Since the only modular forms of weight $\frac12$ on congruence
subgroups of $\SL$ are theta series the theory of Jacobi forms of critical
weight is intimately related to the theory of Weil representations of finite
quadratic modules. This article explains this relation in detail, gives an
account of various facts about Weil representations which are useful in this
context, and it gives some applications of the theory developed herein by
proving various vanishing theorems and by proving a conjecture on Jacobi forms
of weight one on $\SL$ with character.
| [
{
"version": "v1",
"created": "Thu, 5 Jul 2007 05:52:53 GMT"
}
] | 2007-07-06T00:00:00 | [
[
"Skoruppa",
"Nils-Peter",
""
]
] |
0707.0719 | Kourosh Nozari | Kourosh Nozari | Embedding of FRW Cosmology in DGP Scenario with a Non-Minimally Coupled
Scalar Field on the Brane | 14 pages, no figure | Phys.Lett.B652:159-164,2007 | 10.1016/j.physletb.2007.07.015 | null | hep-th | null | We construct a DGP inspired braneworld scenario where a scalar field
non-minimally coupled to the induced Ricci curvature is present on the brane.
We show that this model allows for an embedding of the standard Friedmann
cosmology in the sense that the cosmological evolution of the background metric
on the brane can be described by the standard Friedmann equation. The relation
between our framework and the dark-energy formalism is explored.
| [
{
"version": "v1",
"created": "Thu, 5 Jul 2007 05:59:20 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Nozari",
"Kourosh",
""
]
] |
0707.0720 | S N Sandhya | S. N.Sandhya | Non-classical photon pair generation in atomic vapours | 18 pages, 7 figures | Phys. Rev. A 76 013802 (2007) | 10.1103/PhysRevA.76.013802 | null | quant-ph | null | A scheme for the generation of non-classical pairs of photons in atomic
vapours is proposed. The scheme exploits the fact that the cross correlation of
the emission of photons from the extreme transitions of a four-level cascade
system shows anti-bunching which has not been reported earlier and which is
unlike the case of the three level cascade emission which shows bunching. The
Cauchy-Schwarz inequality which is the ratio of cross-correlation to the auto
correlation function in this case is estimated to be $10^3-10^6$ for
controllable time delay, and is one to four orders of magnitude larger compared
to previous experiments. The choice of Doppler free geometry in addition to the
fact that at three photon resonance the excitation/deexcitation processes occur
in a very narrow frequency band, ensures cleaner signals.
| [
{
"version": "v1",
"created": "Thu, 5 Jul 2007 06:03:37 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Sandhya",
"S. N.",
""
]
] |
0707.0721 | Cosimo Bambi | Cosimo Bambi | Primordial antimatter in the contemporary universe | 8 pages. Talk presented at "SciNeGHE07", 18 - 20 June 2007, Frascati,
Rome, Italy | Frascati Phys. Ser. 45, 129 (2007) | null | null | hep-ph | null | In some baryogenesis scenarios, the universe acquires a non-vanishing average
baryonic charge, but the baryon to photon ratio is not spatially constant and
can be even negative in some space regions. This allows for existence of lumps
of antimatter in our neighborhood and the possibility that very compact
antimatter objects make a part of cosmological dark matter. Here I discuss the
peculiar signatures which may be observed in a near future.
| [
{
"version": "v1",
"created": "Thu, 5 Jul 2007 06:26:00 GMT"
},
{
"version": "v2",
"created": "Wed, 11 Jul 2007 20:25:04 GMT"
}
] | 2008-05-14T00:00:00 | [
[
"Bambi",
"Cosimo",
""
]
] |
0707.0722 | Damian Swift | Damian C. Swift | X-ray diffraction from shock-loaded polycrystals | null | Review of Scientific Instruments, vol 79, no 1, 013906 (2008) | 10.1063/1.2833824 | LA-UR-04-8534 | cond-mat.other cond-mat.mtrl-sci | null | X-ray diffraction was demonstrated from shock-compressed polycrystalline
metal on nanosecond time scales. Laser ablation was used to induce shock waves
in polycrystalline foils of Be, 25 to 125 microns thick. A second laser pulse
was used to generate a plasma x-ray source by irradiation of a Ti foil. The
x-ray source was collimated to produce a beam of controllable diameter, and the
beam was directed at the Be sample. X-rays were diffracted from the sample, and
detected using films and x-ray streak cameras. The diffraction angle was
observed to change with shock pressure. The diffraction angles were consistent
with the uniaxial (elastic) and isotropic (plastic) compressions expected for
the loading conditions used. Polycrystalline diffraction will be used to
measure the response of the crystal lattice to high shock pressures and through
phase changes.
| [
{
"version": "v1",
"created": "Thu, 5 Jul 2007 06:27:56 GMT"
}
] | 2008-01-23T00:00:00 | [
[
"Swift",
"Damian C.",
""
]
] |
0707.0723 | Yasutaka Taniguchi | Yasutaka Taniguchi, Masaaki Kimura, Yoshiko Kanada-En'yo and Hisashi
Horiuchi | Clustering and Triaxial Deformations of $^{40}$Ca | 11pages, 9 figures | Phys.Rev.C76:044317,2007 | 10.1103/PhysRevC.76.044317 | null | nucl-th | null | We have studied the positive-parity states of $^{40}$Ca using antisymmetrized
molecular dynamics (AMD) and the generator coordinate method (GCM). Imposing
two different kinds of constraints on the variational calculation, we have
found various kinds of $^{40}{\rm Ca}$ structures such as a deformed-shell
structure, as well as $\alpha$-$^{36}$Ar and $^{12}$C-$^{28}$Si cluster
structures. After the GCM calculation, we obtained a normal-deformed band and a
superdeformed band together with their side bands associated with triaxial
deformation. The calculated $B(E2)$ values agreed well with empirical data. It
was also found that the normal-deformed and superdeformed bands have a
non-negligible $\alpha$-$^{36}$Ar cluster component and $^{12}$C-$^{28}$Si
cluster component, respectively. This leads to the presence of an
$\alpha$-$^{36}$Ar higher-nodal band occurring above the normal-deformed band.
| [
{
"version": "v1",
"created": "Thu, 5 Jul 2007 06:33:03 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Taniguchi",
"Yasutaka",
""
],
[
"Kimura",
"Masaaki",
""
],
[
"Kanada-En'yo",
"Yoshiko",
""
],
[
"Horiuchi",
"Hisashi",
""
]
] |
0707.0724 | Damien Chablat | Daniel Kanaan (IRCCyN), Philippe Wenger (IRCCyN), Damien Chablat
(IRCCyN) | Workspace Analysis of the Parallel Module of the VERNE Machine | null | Problems of Mechanics 25, 4 (01/12/2006) 26-42 | null | null | cs.RO physics.class-ph | null | The paper addresses geometric aspects of a spatial three-degree-of-freedom
parallel module, which is the parallel module of a hybrid serial-parallel
5-axis machine tool. This parallel module consists of a moving platform that is
connected to a fixed base by three non-identical legs. Each leg is made up of
one prismatic and two pairs of spherical joint, which are connected in a way
that the combined effects of the three legs lead to an over-constrained
mechanism with complex motion. This motion is defined as a simultaneous
combination of rotation and translation. A method for computing the complete
workspace of the VERNE parallel module for various tool lengths is presented.
An algorithm describing this method is also introduced.
| [
{
"version": "v1",
"created": "Thu, 5 Jul 2007 06:43:49 GMT"
}
] | 2007-07-06T00:00:00 | [
[
"Kanaan",
"Daniel",
"",
"IRCCyN"
],
[
"Wenger",
"Philippe",
"",
"IRCCyN"
],
[
"Chablat",
"Damien",
"",
"IRCCyN"
]
] |
0707.0725 | Peihao Huang | Peihao Huang and H. Zheng | Quantum dynamics of a qubit coupled with structured bath | 25 pages, 11 figures | J. Phys.: Condens. Matter 20 (2008) 395233 | 10.1088/0953-8984/20/39/395233 | null | cond-mat.dis-nn cond-mat.mes-hall | null | The dynamics of an unbiased spin-boson model with Lorentzian spectral density
is investigated theoretically in terms of the perturbation theory based on a
unitary transformation. The non-equilibrium correlation function $P(t)$ and
susceptibility $\chi^{\prime\prime}(\omega)$ are calculated for both the
off-resonance case $\Delta\lesssim 0.5\Omega$ and the on-resonance case
$\Delta\sim \Omega$. The approach is checked by the Shiba's relation and the
sum rule. Besides, the coherent-incoherent transition point $\alpha_c$ can be
determined, which has not been demonstrated for the structured bath by previous
authors up to our knowledge.
| [
{
"version": "v1",
"created": "Thu, 5 Jul 2007 07:04:29 GMT"
},
{
"version": "v2",
"created": "Sun, 8 Jul 2007 12:51:49 GMT"
},
{
"version": "v3",
"created": "Fri, 26 Oct 2007 09:36:07 GMT"
}
] | 2008-11-30T00:00:00 | [
[
"Huang",
"Peihao",
""
],
[
"Zheng",
"H.",
""
]
] |
0707.0726 | Carsten Gundlach | David Garfinkle, Carsten Gundlach, David Hilditch | Comments on Bona-Masso type slicing conditions in long-term black hole
evolutions | 14 pages, LaTex, psfrag | Class.Quant.Grav.25:075007,2008 | 10.1088/0264-9381/25/7/075007 | null | gr-qc | null | We review in generality why time-independent endstates can be reached in
black hole and collapse simulations, with and without excision. We characterise
the Killing states of the Bona-Masso slicing condition with time derivative
along the normals to the slice ("BMn") as solutions of a mixed
elliptic/hyperbolic differential equation on the slice. We show numerically
that these steady states can be reached as end states from typical initial data
with excision but can be reached with the puncture method only if the puncture
is not numerically well resolved. During the evolution, BMn slicings often form
gauge shocks. It may be that these are not seen in current 3D simulations only
through lack of resolution, although we expect that they can be avoided with
some care. Finally we point out that excision with BMn as currently implemented
is ill-posed and therefore not expected to converge; this can be cured. In
technical appendixes, we derive the equations of pure gauge systems on a fixed
spacetime, and bring the BSSN/NOR equations into 3-dimensional tensor form
suitable for multiple coordinate patches or spherical polar coordinates.
| [
{
"version": "v1",
"created": "Thu, 5 Jul 2007 07:36:32 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Garfinkle",
"David",
""
],
[
"Gundlach",
"Carsten",
""
],
[
"Hilditch",
"David",
""
]
] |
0707.0727 | Giovanni Alessandrini | Giovanni Alessandrini, Vincenzo Nesi | Beltrami operators, non--symmetric elliptic equations and quantitative
Jacobian bounds | 27 pages | Ann. Acad. Sci. Fenn. Math. 34, 2009, 47-67 | null | null | math.AP | null | In recent studies on the G-convergence of Beltrami operators, a number of
issues arouse concerning injectivity properties of families of quasiconformal
mappings. Bojarski, D'Onofrio, Iwaniec and Sbordone formulated a conjecture
based on the existence of a so-called primary pair. Very recently, Bojarski
proved the existence of one such pair. We provide a general, constructive,
procedure for obtaining a new rich class of such primary pairs. This proof is
obtained as a slight adaptation of previous work by the authors concerning the
nonvanishing of the Jacobian of pairs of solutions of elliptic equations in
divergence form in the plane. It is proven here that the results previously
obtained when the coefficient matrix is symmetric also extend to the
non-symmetric case. We also prove a much stronger result giving a quantitative
bound for the Jacobian determinant of the so-called \emph{periodic}
$\sigma$-harmonic sense preserving homeomorphisms of $\mathbb C$ onto itself.
| [
{
"version": "v1",
"created": "Thu, 5 Jul 2007 07:50:37 GMT"
}
] | 2010-11-09T00:00:00 | [
[
"Alessandrini",
"Giovanni",
""
],
[
"Nesi",
"Vincenzo",
""
]
] |
0707.0728 | Iosif Galanakis | K. Ozdogan, E. Sasioglu, and I. Galanakis | Engineering the electronic, magnetic and gap-related properties of the
quinternary half-metallic Heusler alloys | 17 pages, 10 figures | Journal of Applied Physics 103, 023503 (2008 | 10.1063/1.2831224 | null | cond-mat.mtrl-sci | null | We review the electronic and magnetic properties of the quinternary full
Heusler alloys of the type Co$_2$[Cr$_{1-x}$Mn$_x$][Al$_{1-y}$Si$_y$] employing
three different approaches : (i) the coherent potential approximation (CPA),
(ii) the virtual crystal approximation (VCA), and (iii) supercell calculations
(SC). All three methods give similar results and the local environment
manifested itself only for small details of the density of states. All alloys
under study are shown to be half-metals and their total spin moments follow the
so-called Slater-Pauling behavior of the ideal half-metallic systems. We
especially concentrate on the properties related to the minority-spin band-gap.
We present the possibility to engineer the properties of these alloys by
changing the relative concentrations of the low-valent transition metal and
$sp$ atoms in a continuous way. Our results show that for realistic
applications, ideal are the compounds rich in Si and Cr since they combine
large energy gaps (around 0.6 eV), robust half-metallicity with respect to
defects (the Fermi level is located near the middle of the gap) and high values
of the majority-spin density of states around the Fermi level which are needed
for large values of the perfectly spin-polarized current in spintronic devices
like spin-valves or magnetic tunnel junctions.
| [
{
"version": "v1",
"created": "Thu, 5 Jul 2007 07:54:00 GMT"
}
] | 2015-05-13T00:00:00 | [
[
"Ozdogan",
"K.",
""
],
[
"Sasioglu",
"E.",
""
],
[
"Galanakis",
"I.",
""
]
] |
0707.0729 | Yue Chongxing | Chong-Xing Yue, Nan Zhang, Shi-Hai Zhu | Pair production of the heavy leptons in future high energy linear
e^{+}e^{-} colliders | Discussions added, typos and references corrected | Eur.Phys.J.C53:215-219,2008 | 10.1140/epjc/s10052-007-0455-8 | null | hep-ph | null | The littlest Higgs model with T-parity predicts the existence of the T-odd
particles, which can only be produced in pair. We consider pair production of
the T-odd leptons in future high energy linear $e^{+}e^{-}$ collider ($ILC$).
Our numerical results show that, as long as the T-odd leptons are not too
heavy, they can be copiously produced and their possible signals might be
detected via the processes $e^{+}e^{-}\to \bar{L}_{i}L_{j}$ in future $ILC$
experiments.
| [
{
"version": "v1",
"created": "Thu, 5 Jul 2007 07:57:09 GMT"
},
{
"version": "v2",
"created": "Fri, 3 Aug 2007 13:19:10 GMT"
},
{
"version": "v3",
"created": "Sat, 15 Sep 2007 23:51:51 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Yue",
"Chong-Xing",
""
],
[
"Zhang",
"Nan",
""
],
[
"Zhu",
"Shi-Hai",
""
]
] |
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