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list | update_date
timestamp[s] | authors_parsed
sequence |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
0704.2201 | Hassan Satori | H. Satori, M. Harti and N. Chenfour | Arabic Speech Recognition System using CMU-Sphinx4 | 5 pages, 3 figures and 2 tables, in French | null | null | null | cs.CL cs.AI | null | In this paper we present the creation of an Arabic version of Automated
Speech Recognition System (ASR). This system is based on the open source
Sphinx-4, from the Carnegie Mellon University. Which is a speech recognition
system based on discrete hidden Markov models (HMMs). We investigate the
changes that must be made to the model to adapt Arabic voice recognition.
Keywords: Speech recognition, Acoustic model, Arabic language, HMMs,
CMUSphinx-4, Artificial intelligence.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 17:04:26 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Satori",
"H.",
""
],
[
"Harti",
"M.",
""
],
[
"Chenfour",
"N.",
""
]
] |
0704.2202 | Patrick Rinke | Jorg Behler, Karten Reuter and Matthias Scheffler | Non-adiabatic Effects in the Dissociation of Oxygen Molecules at the
Al(111) Surface | 17 pages including 11 figures; related publications can be found at
http://www.fhi-berlin.mpg.de/th/th.html | null | 10.1103/PhysRevB.77.115421 | null | cond-mat.mtrl-sci | null | The measured low initial sticking probability of oxygen molecules at the
Al(111) surface that had puzzled the field for many years was recently
explained in a non-adiabatic picture invoking spin-selection rules [J. Behler
et al., Phys. Rev. Lett. 94, 036104 (2005)]. These selection rules tend to
conserve the initial spin-triplet character of the free O2 molecule during the
molecule's approach to the surface. A new locally-constrained
density-functional theory approach gave access to the corresponding
potential-energy surface (PES) seen by such an impinging spin-triplet molecule
and indicated barriers to dissociation which reduce the sticking probability.
Here, we further substantiate this non-adiabatic picture by providing a
detailed account of the employed approach. Building on the previous work, we
focus in particular on inaccuracies in present-day exchange-correlation
functionals. Our analysis shows that small quantitative differences in the
spin-triplet constrained PES obtained with different gradient-corrected
functionals have a noticeable effect on the lowest kinetic energy part of the
resulting sticking curve.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 17:04:34 GMT"
},
{
"version": "v2",
"created": "Fri, 7 Dec 2007 18:16:49 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Behler",
"Jorg",
""
],
[
"Reuter",
"Karten",
""
],
[
"Scheffler",
"Matthias",
""
]
] |
0704.2203 | Kevin Jennings | Kevin Jennings | On Abelian Difference Sets with Parameters of 3-dimensional Projective
Geometries | 12 pages | null | null | null | math.CO | null | A difference set is said to have classical parameters if $ (v,k, \lambda) =
(\frac{q^d-1}{q-1}, \frac{q^{d-1}-1}{q-1}, \frac{q^{d-2}-1}{q-1}).$ The case
$d=3$ corresponds to planar difference sets. We focus here on the family of
abelian difference sets with $d=4$. The only known examples of such difference
sets correspond to the projective geometries $PG(3,q)$. We consider an
arbitrary difference set with the parameters of $PG(3,q)$ in an abelian group
and establish constraints on its structure. In particular, we discern embedded
substructures.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 17:25:41 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Jennings",
"Kevin",
""
]
] |
0704.2204 | Bryce Croll | Gordon A.H. Walker, Bryce Croll, Rainer Kuschnig, Andrew Walker,
Slavek M. Rucinski, Jaymie M. Matthews, David B. Guenther, Anthony F.J.
Moffat, Dimitar Sasselov, Werner W. Weiss | The Differential Rotation of Kappa1 Ceti as Observed by MOST | 16 pages, 7 Figures, published in ApJ | Astrophys.J.659:1611-1622,2007 | 10.1086/511851 | null | astro-ph | null | We first reported evidence for differential rotation of Kappa1 Ceti in Paper
I. In this paper we demonstrate that the differential rotation pattern closely
matches that for the Sun. This result is based on additional MOST
(Microvariability & Oscillations of STars) observations in 2004 and 2005, to
complement the 2003 observations discussed in Paper I. Using StarSpotz, a
program developed specifically to analyze MOST photometry, we have solved for
k, the differential rotation coefficient, and P_{EQ}, the equatorial rotation
period using the light curves from all three years. The spots range in latitude
from 10 to 75 degrees and k = 0.090^{+0.006}_{-0.005} -- less than the solar
value but consistent with the younger age of the star. k is also well
constrained by the independent spectroscopic estimate of vsini. We demonstrate
independently that the pattern of differential rotation with latitude in fact
conforms to solar.
Details are given of the parallel tempering formalism used in finding the
most robust solution which gives P_{EQ} = 8.77^{+0.03}_{-0.04} days -- smaller
than that usually adopted, implying an age < 750 My. Our values of P_{EQ} and k
can explain the range of rotation periods determined by others by spots or
activity at a variety of latitudes. Historically, Ca II activity seems to occur
consistently between latitudes 50 and 60 degrees which might indicate a
permanent magnetic feature. Knowledge of k and P_{EQ} are key to understanding
the dynamo mechanism and rotation structure in the convective zone as well
assessing age for solar-type stars. We recently published values of k and
P_{EQ} for epsilon Eri based on MOST photometry and expect to analyze MOST
light curves for several more spotted, solar-type stars.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 17:55:29 GMT"
}
] | 2010-11-05T00:00:00 | [
[
"Walker",
"Gordon A. H.",
""
],
[
"Croll",
"Bryce",
""
],
[
"Kuschnig",
"Rainer",
""
],
[
"Walker",
"Andrew",
""
],
[
"Rucinski",
"Slavek M.",
""
],
[
"Matthews",
"Jaymie M.",
""
],
[
"Guenther",
"David B.",
""
],
[
"Moffat",
"Anthony F. J.",
""
],
[
"Sasselov",
"Dimitar",
""
],
[
"Weiss",
"Werner W.",
""
]
] |
0704.2205 | Maurizio Piai | Maurizio Piai | Vector mesons from AdS/TC to the LHC | 24 pages, 5 figures | null | null | null | hep-ph | null | With the use of the AdS/CFT dictionary, a five-dimensional effective
description of dynamical electro-weak symmetry breaking with walking behavior
is constructed. The minimal model contains only two new parameters, the
confinement scale and the effective coupling of the new strong sector. This
parameter space is restricted by the precision electro-weak constraints and by
the requirement that the five-dimensional coupling be perturbative
(corresponding to the large-N regime in four-dimensional language). The
lightest observable new states are a set of four nearly degenerate spin-1
states with the same quantum numbers as the standard-model electro-weak gauge
bosons, and masses in the few TeV range. Their decay rate is dominated by
two-fermion final states. The number of pp -> mu mu and pp -> mu nu events is
studied as a function of the LHC integrated luminosity and of the two free
parameters. Discovery at the LHC is possible over a significant part of the
allowed parameter space up to masses of 4 TeV already with 10/fm of integrated
luminosity.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 17:50:12 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Piai",
"Maurizio",
""
]
] |
0704.2206 | Immanuel Halupczok | Immanuel Halupczok | Motives for perfect PAC fields with pro-cyclic Galois group | 15 pages, to appear in JSL; minor corrections and one proof replaced
by a sketch of proof and a reference | J. Symbolic Logic, 73 (2008), pp. 1036-1050 | null | null | math.LO math.AG | null | Denef and Loeser defined a map from the Grothendieck ring of sets definable
in pseudo-finite fields to the Grothendieck ring of Chow motives, thus enabling
to apply any cohomological invariant to these sets. We generalize this to
perfect, pseudo algebraically closed fields with pro-cyclic Galois group. In
addition, we define some maps between different Grothendieck rings of definable
sets which provide additional information, not contained in the associated
motive. In particular we infer that the map of Denef-Loeser is not injective.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 17:44:34 GMT"
},
{
"version": "v2",
"created": "Mon, 21 Jan 2008 09:37:05 GMT"
}
] | 2008-06-27T00:00:00 | [
[
"Halupczok",
"Immanuel",
""
]
] |
0704.2207 | David Ellerman | David Ellerman | Adjoint Functors and Heteromorphisms | 28 pages | null | null | null | math.CT math.LO | null | Category theory has foundational importance because it provides conceptual
lenses to characterize what is important in mathematics. Originally the main
lenses were universal mapping properties and natural transformations. In recent
decades, the notion of adjoint functors has moved to center-stage as category
theory's primary tool to characterize what is important in mathematics. Our
focus here is to present a theory of adjoint functors. The basis for the theory
is laid by first showing that the object-to-object "heteromorphisms" between
the objects of different categories (e.g., insertion of generators as a set to
group map) can be rigorously treated within category theory. The heteromorphic
theory shows that all adjunctions arise from the birepresentations of the
heteromorphisms between the objects of different categories.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 17:52:10 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Ellerman",
"David",
""
]
] |
0704.2208 | P. J. C. Spreij | Lorenzo Finesso and Peter Spreij | Factor Analysis and Alternating Minimization | null | in Modeling, Estimation and Control, Festschrift in Honor of
Giorgio Picci on the Occasion of his Sixty-Fifth Birthday (2007) | 10.1007/978-3-540-73570-0 | null | math.PR math.OC | null | In this paper we make a first attempt at understanding how to build an
optimal approximate normal factor analysis model. The criterion we have chosen
to evaluate the distance between different models is the I-divergence between
the corresponding normal laws. The algorithm that we propose for the
construction of the best approximation is of an the alternating minimization
kind.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 17:57:31 GMT"
}
] | 2023-02-27T00:00:00 | [
[
"Finesso",
"Lorenzo",
""
],
[
"Spreij",
"Peter",
""
]
] |
0704.2209 | Barbara Catinella | Barbara Catinella, Martha P. Haynes, Riccardo Giovanelli | Rotational Widths for Use in the Tully-Fisher Relation. II. The Impact
of Surface Brightness | 13 pages, 8 figures. To appear in the Astronomical Journal (August
2007) | Astron.J.134:334-343,2007 | 10.1086/518827 | null | astro-ph | null | Using a large sample of spiral galaxies for which 21 cm single-dish and/or
long-slit optical spectra are available, we make a detailed comparison between
various estimates of rotational widths. Different optical width estimators are
considered and their limitations discussed, with emphasis on biases associated
with rotation curve properties (shape and extent) and disk central surface
brightness. The best match with HI rotational velocities is obtained with
Polyex widths, which are measured at the optical radius (encompassing a fixed
fraction of the total light of the galaxy) from a model fit to the rotation
curve. In contrast with Polyex widths, optical rotational velocities measured
at 2.15 disk scale lengths r_d deviate from HI widths by an amount that
correlates with the central surface brightness of the disk. This bias occurs
because the rotation curves of galaxies are in general still rising at 2.15
r_d, and the fraction of total mass contained within this radius decreases with
increasing disk surface brightness. Statistical corrections, parameterized by
the radial extent of the observed rotation curve, are provided to reduce Polyex
and HI width measurements into a homogeneous system. This yields a single
robust estimate of rotational velocity to be used for applications of disk
scaling relations.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 17:58:41 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Catinella",
"Barbara",
""
],
[
"Haynes",
"Martha P.",
""
],
[
"Giovanelli",
"Riccardo",
""
]
] |
0704.2210 | Steven Willner | Sophia A. Khan, Richard A. Shafer, Stephen Serjeant, S. P.Willner,
Chris P. Pearson, Dominic J. Benford, Johannes G. Staguhn, S. Harvey Moseley,
Timothy J. Sumner, Matthew L. N. Ashby, Colin K. Borys, Pierre Chanial, David
L. Clements, C. Darren Dowell, Eli Dwek, Giovanni G. Fazio, Attila Kov\'acs,
Emeric Le Floc'h, Robert F.Silverberg | First Constraints on Source Counts at 350 Microns | accepted for publication in The Astrophysical Journal | Astrophys.J.665:973-979,2007 | 10.1086/519239 | null | astro-ph | null | We have imaged a $\sim$6 arcminute$^2$ region in the Bo\"otes Deep Field
using the 350 $\mu$m-optimised second generation Submillimeter High Angular
Resolution Camera (SHARC II), achieving a peak 1$\sigma$ sensitivity of $\sim$5
mJy. We detect three sources above 3$\sigma$, and determine a spurious source
detection rate of 1.09 in our maps. In the absence of $5\sigma$ detections, we
rely on deep 24 $\mu$m and 20 cm imaging to deduce which sources are most
likely to be genuine, giving two real sources. From this we derive an integral
source count of 0.84$^{+1.39}_{-0.61}$ sources arcmin$^{-2}$ at $S>13$ mJy,
which is consistent with 350 $\mu$m source count models that have an
IR-luminous galaxy population evolving with redshift. We use these constraints
to consider the future for ground-based short-submillimetre surveys.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 17:59:23 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Khan",
"Sophia A.",
""
],
[
"Shafer",
"Richard A.",
""
],
[
"Serjeant",
"Stephen",
""
],
[
"Willner",
"S. P.",
""
],
[
"Pearson",
"Chris P.",
""
],
[
"Benford",
"Dominic J.",
""
],
[
"Staguhn",
"Johannes G.",
""
],
[
"Moseley",
"S. Harvey",
""
],
[
"Sumner",
"Timothy J.",
""
],
[
"Ashby",
"Matthew L. N.",
""
],
[
"Borys",
"Colin K.",
""
],
[
"Chanial",
"Pierre",
""
],
[
"Clements",
"David L.",
""
],
[
"Dowell",
"C. Darren",
""
],
[
"Dwek",
"Eli",
""
],
[
"Fazio",
"Giovanni G.",
""
],
[
"Kovács",
"Attila",
""
],
[
"Floc'h",
"Emeric Le",
""
],
[
"Silverberg",
"Robert F.",
""
]
] |
0704.2211 | Allan Widom | Soack Dae Yoon, Vincent G. Harris, Carmine Vittoria, Allan Widom | Electronic Transport in the Oxygen Deficient Ferromagnetic
Semiconducting TiO$_{2-\delta}$ | RevTeX4, Four pages, Four Figures in ^.eps format | null | 10.1088/0953-8984/19/32/326202 | null | cond-mat.other | null | TiO$_{2-\delta}$ films were deposited on (100) Lanthanum aluminates
LaAlO$_{3}$ substrates at a very low oxygen chamber pressure $P\approx 0.3$
mtorr employing a pulsed laser ablation deposition technique. In previous work,
it was established that the oxygen deficiency in these films induced
ferromagnetism. In this work it is demonstrated that this same oxygen
deficiency also gives rise to semiconductor titanium ion impurity donor energy
levels. Transport resistivity measurements in thin films of TiO$_{2-\delta}$
are presented as a function of temperature and magnetic field. Magneto- and
Hall- resistivity is explained in terms of electronic excitations from the
titanium ion donor levels into the conduction band.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 18:01:59 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Yoon",
"Soack Dae",
""
],
[
"Harris",
"Vincent G.",
""
],
[
"Vittoria",
"Carmine",
""
],
[
"Widom",
"Allan",
""
]
] |
0704.2212 | Serhiy Zhuk M. | Serhiy Zhuk, Serhiy Demidenko, Alexander Nakonechniy | Minimax State Observation in Linear One Dimensional 2-Point Boundary
Value Problems | 3 pages, 2 figs, to be presented at Int.conf. PDMU-2007
(http://www.unicyb.kiev.ua/ConfPDMU2007) | null | null | null | math.OC | null | In this paper we study observation problem for linear 2-point BVP Dx=Bf
assuming that information about system input f and random noise \eta in system
state observation model y=Hx+\eta$ is incomplete (f and M\eta\eta' are some
arbitrary elements of given sets). A criterion of guaranteed (minimax)
estimation error finiteness is proposed. Representations of minimax estimations
are obtained in terms of 2-point BVP solutions. It is proved that in general
case we can only estimate a projection of system state onto some linear
manifold $F$. In particular, $F=L_2$ if $dim N(D H) = 0$. Also we propose a
procedure which decides if given linear functional belongs to $F$.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 18:09:29 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Zhuk",
"Serhiy",
""
],
[
"Demidenko",
"Serhiy",
""
],
[
"Nakonechniy",
"Alexander",
""
]
] |
0704.2213 | Lucian M. Ionescu | Lucian M. Ionescu | From Lie Theory to Deformation Theory and Quantization | AMSLaTeX, v.1 11 pages, v.2 18p., submitted to SIGMA, special issue
on deformation theory and quantization | null | null | null | math.QA math-ph math.MP | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Deformation Theory is a natural generalization of Lie Theory, from Lie groups
and their linearization, Lie algebras, to differential graded Lie algebras and
their higher order deformations, quantum groups.
The article focuses on two basic constructions of deformation theory: the
universal solution of Maurer-Cartan Equation (MCE), which plays the role of the
exponential of Lie Theory, and its inverse, the Kuranishi functor, as the
logarithm.
The deformation functor is the gauge reduction of MCE, corresponding to a
Hodge decomposition associated to the strong deformation retract data.
The above comparison with Lie Theory leads to a better understanding of
Deformation Theory and its applications, e.g. the relation between quantization
and Connes-Kreimer renormalization, quantum doubles and Birkhoff decomposition.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 18:37:15 GMT"
},
{
"version": "v2",
"created": "Thu, 9 Oct 2008 16:24:18 GMT"
}
] | 2008-10-09T00:00:00 | [
[
"Ionescu",
"Lucian M.",
""
]
] |
0704.2214 | Martin Olsson | William Fulton and Martin Olsson | The Picard group of $M_{1,1}$ | 14 pages | null | null | null | math.AG | null | We compute the Picard group of the moduli stack of elliptic curves and its
canonical compactification over general base schemes.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 18:45:47 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Fulton",
"William",
""
],
[
"Olsson",
"Martin",
""
]
] |
0704.2215 | Steven Simon | M. J. Manfra, R. de Picciotto, Z. Jiang, S. H. Simon, L. N. Pfeiffer,
K. W. West, and A. M. Sergent | Impact of spin-orbit coupling on quantum Hall nematic phases | 4 pages, 4 figures | null | 10.1103/PhysRevLett.98.206804 | null | cond-mat.mes-hall cond-mat.str-el | null | Anisotropic charge transport is observed in a two-dimensional (2D) hole
system in a perpendicular magnetic field at filling factors nu=7/2, nu=11/2,
and nu=13/2 at low temperature. In stark contrast, the transport at nu=9/2 is
isotropic for all temperatures. Isotropic hole transport at nu=7/2 is restored
for sufficiently low 2D densities or an asymmetric confining potential. The
density and symmetry dependences of the observed anisotropies suggest that
strong spin-orbit coupling in the hole system contributes to the unusual
transport behavior.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 18:50:23 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Manfra",
"M. J.",
""
],
[
"de Picciotto",
"R.",
""
],
[
"Jiang",
"Z.",
""
],
[
"Simon",
"S. H.",
""
],
[
"Pfeiffer",
"L. N.",
""
],
[
"West",
"K. W.",
""
],
[
"Sergent",
"A. M.",
""
]
] |
0704.2216 | Mounir Nisse | Mounir Nisse | Maximally Sparse Polynomials have Solid Amoebas | 29 pages, 26 figures | null | null | null | math.AG math.GT | null | Let $f$ be an ordinary polynomial in $\mathbb{C}[z_1,..., z_n]$ with no
negative exponents and with no factor of the form $z_1^{\alpha_1}...
z_n^{\alpha_n}$ where $\alpha_i$ are non zero natural integer. If we assume in
addicting that $f$ is maximally sparse polynomial (that its support is equal to
the set of vertices of its Newton polytope), then a complement component of the
amoeba $\mathscr{A}_f$ in $\mathbb{R}^n$ of the algebraic hypersurface
$V_f\subset (\mathbb{C}^*)^n$ defined by $f$, has order lying in the support of
$f$, which means that $\mathscr{A}_f$ is solid. This gives an affirmative
answer to Passare and Rullg\aa rd question in [PR2-01].
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 18:56:51 GMT"
},
{
"version": "v2",
"created": "Wed, 6 Feb 2008 16:30:52 GMT"
}
] | 2015-03-13T00:00:00 | [
[
"Nisse",
"Mounir",
""
]
] |
0704.2217 | Alejandra Kandus | Alejandra Kandus | Analysis of the Effect of a Mean Velocity Field on Mean Field Dynamo | 9 pages, 10 figures, accepted for publication in MNRAS | null | 10.1111/j.1365-2966.2007.11863.x | null | physics.plasm-ph astro-ph physics.flu-dyn | null | We study semi-analytically and in a consistent manner, the generation of a
mean velocity field $\bar{\mathbf{U}}$ by helical MHD turbulence, and the
effect that this field can have on a Mean Field Dynamo. Assuming a prescribed,
maximally helical small scale velocity field, we show that large scale flows
can be generated in MHD turbulent flows, via small scale Lorentz force. These
flows back-react on the mean electromotive force of a Mean Field Dynamo through
new terms, leaving the original $\alpha $ and $\beta $ terms explicitly
unmodified. Cross-helicity plays the key role in interconnecting all the
effects. In the minimal $\tau$ closure that we chose to work with, the effects
are stronger for large relaxation times.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 19:06:22 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Kandus",
"Alejandra",
""
]
] |
0704.2218 | Giacomo Marmorini | Minoru Eto, Jarah Evslin, Kenichi Konishi, Giacomo Marmorini, Muneto
Nitta, Keisuke Ohashi, Walter Vinci, Naoto Yokoi | On the moduli space of semilocal strings and lumps | 1+48 pages, 5 fig. v2 several changes to secton 6.3, sections 6.4 and
6.5 added | Phys.Rev.D76:105002,2007 | 10.1103/PhysRevD.76.105002 | null | hep-th | null | We study BPS non-abelian semilocal vortices in U(Nc) gauge theory with Nf
flavors, Nf > Nc, in the Higgs phase. The moduli space for arbitrary winding
number is described using the moduli matrix formalism. We find a relation
between the moduli spaces of the semilocal vortices in a Seiberg-like dual
pairs of theories, U(Nc) and U(Nf-Nc). They are two alternative regularizations
of a "parent" non-Hausdorff space, which tend to the same moduli space of
sigma-model lumps in the infinite gauge coupling limits. We examine the
normalizability of the zero-modes and find the somewhat surprising phenomenon
that the number of normalizable zero-modes, dynamical fields in the effective
action, depends on the point of the moduli space we are considering. We find,
in the lump limit, an effective action on the vortex worldsheet, which we
compare to that found by Shifman and Yung.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 19:56:29 GMT"
},
{
"version": "v2",
"created": "Thu, 28 Jun 2007 19:08:03 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Eto",
"Minoru",
""
],
[
"Evslin",
"Jarah",
""
],
[
"Konishi",
"Kenichi",
""
],
[
"Marmorini",
"Giacomo",
""
],
[
"Nitta",
"Muneto",
""
],
[
"Ohashi",
"Keisuke",
""
],
[
"Vinci",
"Walter",
""
],
[
"Yokoi",
"Naoto",
""
]
] |
0704.2219 | Mikhail V. Ioffe | F. Cannata, M.V. Ioffe, D.N. Nishnianidze | Pseudo-Hermiticity of an Exactly Solvable Two-Dimensional Model | 14 pages | Phys.Lett.A369:9-15,2007 | 10.1016/j.physleta.2007.04.056 | null | hep-th math-ph math.MP quant-ph | null | We study a two-dimensional exactly solvable non-Hermitian $PT-$non-symmetric
quantum model with real spectrum, which is not amenable to separation of
variables, by supersymmetrical methods. Here we focus attention on the property
of pseudo-Hermiticity, biorthogonal expansion and pseudo-metric operator. To
our knowledge this is the first time that pseudo-Hermiticity is realized
explicitly for a nontrivial two-dimensional case. It is shown that the
Hamiltonian of the model is not diagonalizable.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 19:07:15 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Cannata",
"F.",
""
],
[
"Ioffe",
"M. V.",
""
],
[
"Nishnianidze",
"D. N.",
""
]
] |
0704.2220 | Guillermo Gonzalez | Guillermo Gonzalez, Chris Laws | Parent Stars of Extrasolar Planets. VIII. Chemical Abundances for 18
Elements in 31 Stars | to be published in MNRAS; 16 pages; contains 8 figures and 8 tables | Mon.Not.Roy.Astron.Soc.378:1141-1152,2007 | 10.1111/j.1365-2966.2007.11867.x | null | astro-ph | null | We present the results of detailed spectroscopic abundance analyses for 18
elements in 31 nearby stars with planets. The resulting abundances are combined
with other similar studies of nearby stars with planets and compared to a
sample of nearby stars without detected planets. We find some evidence for
abundance differences between these two samples for Al, Si and Ti. Some of our
results are in conflict with a recent study of stars with planets in the SPOCS
database. We encourage continued study of the abundance patterns of stars with
planets to resolve these discrepancies.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 19:16:05 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Gonzalez",
"Guillermo",
""
],
[
"Laws",
"Chris",
""
]
] |
0704.2221 | Dazhi Liu | Dazhi Liu, Yang Zhang, Chia-Cheng Chen, Chung-Yuan Mou, Peter H Poole,
Sow-Hsin Chen | Observation of the Density Minimum in Deeply Supercooled Confined Water | null | null | 10.1073/pnas.0701352104 | null | cond-mat.soft | null | Small angle neutron scattering (SANS) is used to measure the density of heavy
water contained in 1-D cylindrical pores of mesoporous silica material
MCM-41-S-15, with pores of diameter of 15+-1 A. In these pores the homogenous
nucleation process of bulk water at 235 K does not occur and the liquid can be
supercooled down to at least 160 K. The analysis of SANS data allows us to
determine the absolute value of the density of D2O as a function of
temperature. We observe a density minimum at 210+-5 K with a value of
1.041+-0.003 g/cm3. We show that the results are consistent with the
predictions of molecular dynamics simulations of supercooled bulk water. This
is the first experimental report of the existence of the density minimum in
supercooled water.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 19:22:43 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Liu",
"Dazhi",
""
],
[
"Zhang",
"Yang",
""
],
[
"Chen",
"Chia-Cheng",
""
],
[
"Mou",
"Chung-Yuan",
""
],
[
"Poole",
"Peter H",
""
],
[
"Chen",
"Sow-Hsin",
""
]
] |
0704.2222 | Michael Kroyter | Ehud Fuchs, Michael Kroyter, Robertus Potting | Marginal deformations in string field theory | 23 pages. v2: Some paragraphs improved, typos corrected, ref added | JHEP0709:101,2007 | 10.1088/1126-6708/2007/09/101 | AEI-2007-023 | hep-th | null | We describe a method for obtaining analytic solutions corresponding to exact
marginal deformations in open bosonic string field theory. For the photon
marginal deformation we have an explicit analytic solution to all orders. Our
construction is based on a pure gauge solution where the gauge field is not in
the Hilbert space. We show that the solution itself is nevertheless perfectly
regular. We study its gauge transformations and calculate some coefficients
explicitly. Finally, we discuss how our method can be implemented for other
marginal deformations.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 19:45:56 GMT"
},
{
"version": "v2",
"created": "Fri, 28 Sep 2007 19:09:57 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Fuchs",
"Ehud",
""
],
[
"Kroyter",
"Michael",
""
],
[
"Potting",
"Robertus",
""
]
] |
0704.2223 | John Coleman | A. John Coleman | Whitehead's Trilogy and the Curvature of Spacetime | null | null | null | null | physics.gen-ph physics.hist-ph | null | My object in the present paper is to: (1) introduce physicists to the life
and work of Whitehead; (2) outline the content of his book "The Principle of
Relativity"; (3) present Whitehead's basic criticism of the General Theory of
Relativity which, to my mind, has never been rebutted or properly appreciated,
even by GTR specialists; (4) propose a significant relevant research problem;
and (5) summarize some of the rather radical implications of the acceptance of
Whitehead's observations, including that spacetime is not curved.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 19:25:17 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Coleman",
"A. John",
""
]
] |
0704.2224 | Enrique Moreno | G. S. Lozano, D. Marques, E. F. Moreno and F. A. Schaposnik | Non-Abelian Chern-Simons Vortices | 12 pages, 3 figures. Shortened version, published in Phys. Lett. B | Phys.Lett.B654:27-34,2007 | 10.1016/j.physletb.2007.08.036 | null | hep-th | null | We consider the bosonic sector of a N=2 supersymmetric Chern-Simons-Higgs
theory in 2+1 dimensions. The gauge group is U(1)xU(N) and has N_f flavors of
fundamental matter fields. The model supports non-Abelian (axially symmetric)
vortices when N_f\geq N, which have internal (orientational) moduli. When N_f >
N, the solutions acquire additional collective coordinates parameterizing their
transverse size. We solve the BPS equations numerically and obtain local (N_f =
N) and semi-local (N_f > N) string solutions.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 19:27:44 GMT"
},
{
"version": "v2",
"created": "Mon, 24 Sep 2007 14:13:02 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Lozano",
"G. S.",
""
],
[
"Marques",
"D.",
""
],
[
"Moreno",
"E. F.",
""
],
[
"Schaposnik",
"F. A.",
""
]
] |
0704.2225 | Cesar Seoanez | C. Seoanez, F. Guinea, A. H. Castro Neto | Dissipation in graphene and nanotube resonators | Published version with updated references | Phys. Rev. B 76, 125427 (2007) | 10.1103/PhysRevB.76.125427 | null | cond-mat.mes-hall cond-mat.mtrl-sci | null | Different damping mechanisms in graphene nanoresonators are studied: charges
in the substrate, ohmic losses in the substrate and the graphene sheet,
breaking and healing of surface bonds (Velcro effect), two level systems,
attachment losses, and thermoelastic losses. We find that, for realistic
structures and contrary to semiconductor resonators, dissipation is dominated
by ohmic losses in the graphene layer and metallic gate. An extension of this
study to carbon nanotube-based resonators is presented.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 19:28:40 GMT"
},
{
"version": "v2",
"created": "Sat, 7 Jul 2007 18:15:34 GMT"
},
{
"version": "v3",
"created": "Fri, 21 Sep 2007 08:50:23 GMT"
}
] | 2011-11-09T00:00:00 | [
[
"Seoanez",
"C.",
""
],
[
"Guinea",
"F.",
""
],
[
"Neto",
"A. H. Castro",
""
]
] |
0704.2226 | Tim Davidge | Sidney van den Bergh | The Luminosity Distribution of Globular Clusters in Dwarf Galaxies | Astronomical Journal, in press | Astron.J.134:344-345,2007 | 10.1086/518868 | null | astro-ph | null | The majority of the globular clusters associated with the Sagittarius dwarf
galaxy are faint. In this respect it differs significantly from the globular
cluster systems surrounding typical giant galaxies. The observation that most
of globular clusters in the outer halo of the Galaxy are also sub-luminous may
be understood by assuming that these clusters once also belonged to faint
cluster-rich dwarf systems that were subsequently captured and destroyed by the
Milky Way System.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 19:32:17 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Bergh",
"Sidney van den",
""
]
] |
0704.2227 | J\'er\^ome B\"urki | J. B\"urki | Front propagation into unstable metal nanowires | 6 pages, 4 figures | Phys. Rev. E 76, 026317 (2007) | 10.1103/PhysRevE.76.026317 | null | cond-mat.mes-hall | null | Long, cylindrical metal nanowires have recently been observed to form and be
stable for seconds at a time at room temperature. Their stability and
structural dynamics is well described by a continuum model, the nanoscale
free-electron model, which predicts cylinders in certain intervals of radius to
be linearly unstable. In this paper, I study how a small, localized
perturbation of such an unstable wire grows exponentially and propagates along
the wire with a well-defined front. The front is found to be pulled, and forms
a coherent pattern behind it. It is well described by a linear marginal
stability analysis of front propagation into an unstable state. In some cases,
nonlinearities of the wire dynamics are found to trigger an invasive mode that
pushes the front. Experimental procedures that could lead to the observation of
this phenomenon are suggested.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 19:40:52 GMT"
}
] | 2008-07-09T00:00:00 | [
[
"Bürki",
"J.",
""
]
] |
0704.2228 | Sinue Serra | Eduard Salvador-Sol\'e, Sinue Serra, Rosa Dom\'inguez-Tenreiro,
Alberto Manrique | The Density Profile of Local Ellipticals as Violently Relaxed,
Collisionless, Dissipationless Systems | 4 pages, 2 figures | null | null | null | astro-ph | null | In a series of recent papers, a new formalism has been developed that
explains the inner structure of dark matter halos as collisionless,
dissipationless systems assembled through mergers and accretion at the typical
cosmological rate. Nearby ellipticals are also collisionless, dissipationless
systems assembling their mass through mergers, but contrarily to the former
structures they do not continuously accrete external matter because they are
shielded by their host halos. Here we explore the idea that the infall of their
own matter ejected within the halo on the occasion of a violent merger can play
a role similar to external accretion in halos. The predicted stellar mass
density profile fits the observed one, and the empirical total mass density
profile is also recovered.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 20:04:04 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Salvador-Solé",
"Eduard",
""
],
[
"Serra",
"Sinue",
""
],
[
"Domínguez-Tenreiro",
"Rosa",
""
],
[
"Manrique",
"Alberto",
""
]
] |
0704.2229 | Stefan Vandoren | Frank Saueressig and Stefan Vandoren | Conifold singularities, resumming instantons and non-perturbative mirror
symmetry | 14 pages, 1 figure | JHEP 0707:018,2007 | 10.1088/1126-6708/2007/07/018 | null | hep-th | null | We determine the instanton corrected hypermultiplet moduli space in type IIB
compactifications near a Calabi-Yau conifold point where the size of a
two-cycle shrinks to zero. We show that D1-instantons resolve the conifold
singularity caused by worldsheet instantons. Furthermore, by resumming the
instanton series, we reproduce exactly the results obtained by Ooguri and Vafa
on the type IIA side, where membrane instantons correct the hypermultiplet
moduli space. Our calculations therefore establish that mirror symmetry holds
non-perturbatively in the string coupling.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 18:19:31 GMT"
},
{
"version": "v2",
"created": "Thu, 26 Apr 2007 10:19:30 GMT"
}
] | 2010-02-03T00:00:00 | [
[
"Saueressig",
"Frank",
""
],
[
"Vandoren",
"Stefan",
""
]
] |
0704.2230 | Petr Horava | Petr Horava, Cynthia A. Keeler | Strings on AdS_2 and the High-Energy Limit of Noncritical M-Theory | 31 pages; references added | JHEP 0706:031,2007 | 10.1088/1126-6708/2007/06/031 | null | hep-th | null | Noncritical M-theory in 2+1 dimensions has been defined as a double-scaling
limit of a nonrelativistic Fermi liquid on a flat two-dimensional plane. Here
we study this noncritical M-theory in the limit of high energies, analogous to
the \alpha'\to\infty limit of string theory. In the related case of
two-dimensional Type 0A strings, it has been argued that the conformal
\alpha'\to\infty limit leads to AdS_2 with a propagating fermion whose mass is
set by the value of the RR flux. Here we provide evidence that in the
high-energy limit, the natural ground state of noncritical M-theory similarly
describes the AdS_2\times S^1 spacetime, with a massless propagating fermion.
We argue that the spacetime effective theory in this background is captured by
a topological higher-spin extension of conformal Chern-Simons gravity in 2+1
dimensions, consistently coupled to a massless Dirac field. Intriguingly, the
two-dimensional plane populated by the original nonrelativistic fermions is
essentially the twistor space associated with the symmetry group of the
AdS_2\times S^1 spacetime; thus, at least in the high-energy limit, noncritical
M-theory can be nonperturbatively described as a "Fermi liquid on twistor
space."
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 18:40:40 GMT"
},
{
"version": "v2",
"created": "Mon, 28 May 2007 21:14:36 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Horava",
"Petr",
""
],
[
"Keeler",
"Cynthia A.",
""
]
] |
0704.2231 | Jorge Quintanilla | J. Quintanilla, C. Hooley, B. J. Powell, A. J. Schofield and M. Haque | Pomeranchuk instability: symmetry breaking and experimental signatures | corrected typos, added and updated references, better-resolution
figures | Physica B: Condensed Matter 403, 1279-1281 (2008) [Proceedings of
SCES'07] | 10.1016/j.physb.2007.10.126 | null | cond-mat.str-el | null | We discuss the emergence of symmetry-breaking {\it via} the Pomeranchuk
instability from interactions that respect the underlying point-group symmetry.
We use a variational mean-field theory to consider a 2D continuum and a square
lattice. We describe two experimental signatures: a symmetry-breaking pattern
of Friedel oscillations around an impurity; and a structural transition.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 20:01:05 GMT"
},
{
"version": "v2",
"created": "Fri, 25 Apr 2008 20:12:40 GMT"
}
] | 2008-04-25T00:00:00 | [
[
"Quintanilla",
"J.",
""
],
[
"Hooley",
"C.",
""
],
[
"Powell",
"B. J.",
""
],
[
"Schofield",
"A. J.",
""
],
[
"Haque",
"M.",
""
]
] |
0704.2232 | Chris Quigg | Chris Quigg | Spontaneous Symmetry Breaking as a Basis of Particle Mass | 43 pages, 18 figures, uses IOP macros (included); two typos corrected | Rept.Prog.Phys.70:1019-1054,2007 | 10.1088/0034-4885/70/7/R01 | FERMILAB-PUB-07/030-T | hep-ph hep-ex | null | Electroweak theory joins electromagnetism with the weak force in a single
quantum field theory, ascribing the two fundamental interactions--so different
in their manifestations--to a common symmetry principle. How the electroweak
gauge symmetry is hidden is one of the most urgent and challenging questions
facing particle physics. The provisional answer incorporated in the "standard
model" of particle physics was formulated in the 1960s by Higgs, by Brout &
Englert, and by Guralnik, Hagen & Kibble: The agent of electroweak symmetry
breaking is an elementary scalar field whose self-interactions select a vacuum
state in which the full electroweak symmetry is hidden, leaving a residual
phase symmetry of electromagnetism. By analogy with the Meissner effect of the
superconducting phase transition, the Higgs mechanism, as it is commonly known,
confers masses on the weak force carriers W and Z. It also opens the door to
masses for the quarks and leptons, and shapes the world around us. It is a good
story--though an incomplete story--and we do not know how much of the story is
true. Experiments that explore the Fermi scale (the energy regime around 1 TeV)
during the next decade will put the electroweak theory to decisive test, and
may uncover new elements needed to construct a more satisfying completion of
the electroweak theory. The aim of this article is to set the stage by
reporting what we know and what we need to know, and to set some "Big
Questions" that will guide our explorations.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 20:01:08 GMT"
},
{
"version": "v2",
"created": "Mon, 28 May 2007 02:43:58 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Quigg",
"Chris",
""
]
] |
0704.2233 | James T. Liu | Bin Chen, Sera Cremonini, Aristomenis Donos, Feng-Li Lin, Hai Lin,
James T. Liu, Diana Vaman and Wen-Yu Wen | Bubbling AdS and droplet descriptions of BPS geometries in IIB
supergravity | 94 pages, 6 figures, latex, typos corrected, references added, one
new Appendix | JHEP0710:003,2007 | 10.1088/1126-6708/2007/10/003 | Brown-HET-1480, MCTP-07-15, NSF-KITP-07-58 | hep-th | null | This paper focuses on supergravity duals of BPS states in N=4 super
Yang-Mills. In order to describe these duals, we begin with a sequence of
breathing mode reductions of IIB supergravity: first on S^3, then S^3 x S^1,
and finally on S^3 x S^1 x CP^1. We then follow with a complete supersymmetry
analysis, yielding 1/8, 1/4 and 1/2 BPS configurations, respectively (where in
the last step we take the Hopf fibration of S^3). The 1/8 BPS geometries, which
have an S^3 isometry and are time-fibered over a six-dimensional base, are
determined by solving a non-linear equation for the Kahler metric on the base.
Similarly, the 1/4 BPS configurations have an S^3 x S^1 isometry and a
four-dimensional base, whose Kahler metric obeys another non-linear,
Monge-Ampere type equation.
Despite the non-linearity of the problem, we develop a universal bubbling AdS
description of these geometries by focusing on the boundary conditions which
ensure their regularity. In the 1/8 BPS case, we find that the S^3 cycle
shrinks to zero size on a five-dimensional locus inside the six-dimensional
base. Enforcing regularity of the full solution requires that the interior of a
smooth, generally disconnected five-dimensional surface be removed from the
base. The AdS_5 x S^5 ground state corresponds to excising the interior of an
S^5, while the 1/8 BPS excitations correspond to deformations (including
topology change) of the S^5 and/or the excision of additional droplets from the
base. In the case of 1/4 BPS configurations, by enforcing regularity
conditions, we identify three-dimensional surfaces inside the four-dimensional
base which separate the regions where the S^3 shrinks to zero size from those
where the S^1 shrinks.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 23:07:49 GMT"
},
{
"version": "v2",
"created": "Wed, 29 Aug 2007 15:53:36 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Chen",
"Bin",
""
],
[
"Cremonini",
"Sera",
""
],
[
"Donos",
"Aristomenis",
""
],
[
"Lin",
"Feng-Li",
""
],
[
"Lin",
"Hai",
""
],
[
"Liu",
"James T.",
""
],
[
"Vaman",
"Diana",
""
],
[
"Wen",
"Wen-Yu",
""
]
] |
0704.2234 | Igor Herbut | Igor F. Herbut | Zero-energy states and fragmentation of spin in the easy-plane
antiferromagnet on a honeycomb lattice | 4 pages; cosmetic changes; published version | Phys. Rev. Lett. vol. 99, 206404 (2007) | 10.1103/PhysRevLett.99.206404 | null | cond-mat.str-el cond-mat.mes-hall hep-th | null | The core of the vortex in the Neel order parameter for an easy-plane
antiferromagnet on honeycomb lattice is demonstrated to bind two zero-energy
states. Remarkably, a single electron occupying this mid-gap band has its spin
fragmented between the two sublattices: Whereas it yields a vanishing total
magnetization it shows a finite Neel order, orthogonal to the one of the
assumed background. The requisite easy-plane anisotropy may be introduced by a
magnetic field parallel to the graphene layer, for example. The results are
relevant for spin-1/2 fermions on graphene's or optical honeycomb lattice, in
the strongly interacting regime.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 18:38:14 GMT"
},
{
"version": "v2",
"created": "Wed, 25 Apr 2007 20:13:18 GMT"
},
{
"version": "v3",
"created": "Fri, 16 Nov 2007 21:46:15 GMT"
}
] | 2009-05-20T00:00:00 | [
[
"Herbut",
"Igor F.",
""
]
] |
0704.2235 | Vanessa Mangano | V. Mangano, S.T. Holland, D. Malesani, E. Troja, G. Chincarini, B.
Zhang, V. La Parola, P.J. Brown, D.N. Burrows, S. Campana, M. Capalbi, G.
Cusumano, M. Della Valle, N. Gehrels, P. Giommi, D. Grupe, C. Guidorzi, T.
Mineo, A. Moretti, J.P. Osborne, S.B. Pandey, M. Perri, P. Romano, P.W.A.
Roming, G. Tagliaferri | Swift observations of GRB 060614: an anomalous burst with a well behaved
afterglow | 20 pages, 9 figures, 8 tables. Abstract shortened for posting on
astro-ph. Accepted for publication by A&A | Astron.Astrophys. 470 (2007) 105-118 | 10.1051/0004-6361:20077232 | null | astro-ph | null | GRB 060614 is a remarkable GRB observed by Swift with puzzling properties,
which challenge current progenitor models. The lack of any bright SN down to
very strict limits and the vanishing spectral lags are typical of short GRBs,
strikingly at odds with the long (102s) duration of this event. Here we present
spectral and temporal analysis of the Swift observations. We show that the
burst presents standard optical, UV and X-ray afterglows. An achromatic break
is observed simultaneously in optical and X-rays, at a time consistent with the
break in the R-band light curve measured by the VLT. The achromatic behaviour
and the consistent post-break decay slopes make GRB 060614 one of the best
examples of a jet break for a Swift burst. The optical, UV and X-rays afterglow
light curves have also an earlier break at ~30 ks. In the optical, there is
strong spectral evolution around this break, suggesting the passage of a break
frequency through the optical/UV band. The very blue spectrum at early times
and the trend in the light curves (rising at low frequencies, and decaying at
higher energies) suggest this may be the injection frequency. The early X-ray
light curve is well interpreted as the X-ray counterpart of the burst extended
emission. Spectral analysis of BAT/XRT data in the 80s overlap time show that
the Ep of the burst has decreased to as low as 8keV at the beginning of the XRT
observation. The Ep continues to decrease through the XRT energy band and exits
it at about 500s after the trigger. The average Ep of the burst is likely < 24
keV but larger than 8 keV. The initial peak observed by BAT is however
distinctly harder than the rest with Ep ~300 keV as measured by Konus Wind.
Considering the time-averaged spectral properties, GRB 060614 is consistent
with the Eiso-Ep_rest, Egamma-Ep_rest, and Liso-Ep correlations.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 20:14:33 GMT"
}
] | 2007-07-11T00:00:00 | [
[
"Mangano",
"V.",
""
],
[
"Holland",
"S. T.",
""
],
[
"Malesani",
"D.",
""
],
[
"Troja",
"E.",
""
],
[
"Chincarini",
"G.",
""
],
[
"Zhang",
"B.",
""
],
[
"La Parola",
"V.",
""
],
[
"Brown",
"P. J.",
""
],
[
"Burrows",
"D. N.",
""
],
[
"Campana",
"S.",
""
],
[
"Capalbi",
"M.",
""
],
[
"Cusumano",
"G.",
""
],
[
"Della Valle",
"M.",
""
],
[
"Gehrels",
"N.",
""
],
[
"Giommi",
"P.",
""
],
[
"Grupe",
"D.",
""
],
[
"Guidorzi",
"C.",
""
],
[
"Mineo",
"T.",
""
],
[
"Moretti",
"A.",
""
],
[
"Osborne",
"J. P.",
""
],
[
"Pandey",
"S. B.",
""
],
[
"Perri",
"M.",
""
],
[
"Romano",
"P.",
""
],
[
"Roming",
"P. W. A.",
""
],
[
"Tagliaferri",
"G.",
""
]
] |
0704.2236 | Michal Horodecki | Dong Yang, Karol Horodecki, Michal Horodecki, Pawel Horodecki,
Jonathan Oppenheim, Wei Song | Squashed entanglement for multipartite states and entanglement measures
based on the mixed convex roof | improved version, 13 pages, 1 figure | IEEE Trans. Inf. Theory 55, 3375 (2009) | 10.1109/TIT.2009.2021373 | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | New measures of multipartite entanglement are constructed based on two
definitions of multipartite information and different methods of optimizing
over extensions of the states. One is a generalization of the squashed
entanglement where one takes the mutual information of parties conditioned on
the state's extension and takes the infimum over such extensions. Additivity of
the multipartite squashed entanglement is proved for both versions of the
multipartite information which turn out to be related. The second one is based
on taking classical extensions. This scheme is generalized, which enables to
construct measures of entanglement based on the {\it mixed convex roof} of a
quantity, which in contrast to the standard convex roof method involves
optimization over all decompositions of a density matrix rather than just the
decompositions into pure states. As one of the possible applications of these
results we prove that any multipartite monotone is an upper bound on the amount
of multipartite distillable key. The findings are finally related to analogous
results in classical key agreement.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 20:27:29 GMT"
},
{
"version": "v2",
"created": "Thu, 10 May 2007 10:55:00 GMT"
},
{
"version": "v3",
"created": "Thu, 23 Jul 2009 16:02:19 GMT"
}
] | 2016-11-18T00:00:00 | [
[
"Yang",
"Dong",
""
],
[
"Horodecki",
"Karol",
""
],
[
"Horodecki",
"Michal",
""
],
[
"Horodecki",
"Pawel",
""
],
[
"Oppenheim",
"Jonathan",
""
],
[
"Song",
"Wei",
""
]
] |
0704.2237 | Nadav Drukker | Nadav Drukker, Simone Giombi, Riccardo Ricci and Diego Trancanelli | More supersymmetric Wilson loops | 9 pages, LaTeX | Phys.Rev.D76:107703,2007 | 10.1103/PhysRevD.76.107703 | HU-EP-07/13, YITP-SB-07-12, Imperial/TP/07/RR/02 | hep-th | null | We present a large new family of Wilson loop operators in N=4 supersymmetric
Yang-Mills theory. For an arbitrary curve on the three dimensional sphere one
can add certain scalar couplings to the Wilson loop so it preserves at least
two supercharges. Some previously known loops, notably the 1/2 BPS circle,
belong to this class, but we point out many more special cases which were not
known before and could provide further tests of the AdS/CFT correspondence.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 14:25:53 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Drukker",
"Nadav",
""
],
[
"Giombi",
"Simone",
""
],
[
"Ricci",
"Riccardo",
""
],
[
"Trancanelli",
"Diego",
""
]
] |
0704.2238 | Nobunari Kashikawa | Nobunari Kashikawa, Tetsu Kitayama, Mamoru Doi, Toru Misawa, Yutaka
Komiyama, and Kazuaki Ota | The Habitat Segregation between Lyman Break Galaxies and Lyman alpha
Emitters around a QSO at z~5 | Accepted for publication in APJ. Version with high resolution figures
available at http://zone.mtk.nao.ac.jp/~kashik/z5qso/z5qso_full.pdf | Astrophys.J.663:765-773,2007 | 10.1086/518410 | null | astro-ph | null | We carried out a target survey for Lyman break galaxies (LBGs) and Lyman
alpha emitters (LAEs) around QSO SDSS J0211-0009 at z=4.87. The deep and wide
broadband and narrowband imaging simultaneously revealed the perspective
structure of these two high-z populations. The LBGs without Ly-alpha emission
form a filamentary structure including the QSO, while the LAEs are distributed
around the QSO but avoid it within a distance of ~4.5Mpc. On the other hand, we
serendipitously discovered a protocluster with a significant concentration of
LBGs and LAEs where no strongly UV ionizing source such as a QSO or radio
galaxy is known to exist. In this cluster field, two populations are spatially
cross-correlated with each other. The relative spatial distribution of LAEs to
LBGs is in stark contrast between the QSO and the cluster fields. We also found
a weak trend showing that the number counts based on Ly-alpha and UV continuum
fluxes of LAEs in the QSO field are slightly lower than in the cluster field,
whereas the number counts of LBGs are almost consistent with each other. The
LAEs avoid the nearby region around the QSO where the local UV background
radiation could be ~100 times stronger than the average for the epoch. The
clustering segregation between LBGs and LAEs seen in the QSO field could be due
to either enhanced early galaxy formation in an overdense environment having
caused all the LAEs to evolve into LBGs, or local photoionization due to the
strong UV radiation from the QSO effectively causing a deficit in low-mass
galaxies like LAEs.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 21:03:52 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Kashikawa",
"Nobunari",
""
],
[
"Kitayama",
"Tetsu",
""
],
[
"Doi",
"Mamoru",
""
],
[
"Misawa",
"Toru",
""
],
[
"Komiyama",
"Yutaka",
""
],
[
"Ota",
"Kazuaki",
""
]
] |
0704.2239 | Matthew McQuinn | Matthew McQuinn, Lars Hernquist, Matias Zaldarriaga, Suvendra Dutta
(Harvard-CFA) | Studying Reionization with Ly-alpha Emitters | 24 pages, 17 figures, accepted by MNRAS | Mon.Not.Roy.Astron.Soc. 381: 75-96, 2007 | 10.1111/j.1365-2966.2007.12085.x | null | astro-ph | null | We show that observations of high-redshift Ly-alpha emitters (LAEs) have the
potential to provide definitive evidence for reionization in the near future.
Using 200 Mpc radiative transfer simulations, we calculate the effect that
patchy reionization has on the line profile, on the luminosity function, and,
most interestingly, on the clustering of emitters for several realistic models
of reionization. Reionization increases the measured clustering of emitters,
and we show that this enhancement would be essentially impossible to attribute
to anything other than reionization. Our results motivate looking for the
signature of reionization in existing LAE data. We find that for stellar
reionization scenarios the angular correlation function of the 58 LAEs in the
Subaru Deep Field z = 6.6 photometric sample is more consistent with a fully
ionized universe (mean volume ionized fraction x_i = 1) than a universe with
x_i < 0.5 at >2-sigma confidence level. Measurements in the next year on Subaru
will increase their z = 6.6 LAE sample by a factor of five and tighten these
limits. If the clustering signature of reionization is detected in a LAE
survey, a comparison with a Lyman-break or a H-alpha survey in the same field
would confirm the reionization hypothesis. We discuss the optimal LAE survey
specifications for detecting reionization, with reference to upcoming programs.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 18:08:10 GMT"
},
{
"version": "v2",
"created": "Sat, 21 Apr 2007 20:06:36 GMT"
},
{
"version": "v3",
"created": "Tue, 26 Jun 2007 21:02:47 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"McQuinn",
"Matthew",
"",
"Harvard-CFA"
],
[
"Hernquist",
"Lars",
"",
"Harvard-CFA"
],
[
"Zaldarriaga",
"Matias",
"",
"Harvard-CFA"
],
[
"Dutta",
"Suvendra",
"",
"Harvard-CFA"
]
] |
0704.2240 | Matthias Stute | Matthias Stute, Raghvendra Sahai (Jet Propulsion Laboratory,
California Institute of Technology) | Hydrodynamical simulations of the jet in the symbiotic star MWC 560 III.
Application to X-ray jets in symbiotic stars | 10 pages, 12 figures, accepted for publication in ApJ, uses
emulateapj | Astrophys.J.665:698-706,2007 | 10.1086/518930 | null | astro-ph | null | In papers I and II in this series, we presented hydrodynamical simulations of
jet models with parameters representative of the symbiotic system MWC 560.
These were simulations of a pulsed, initially underdense jet in a high density
ambient medium. Since the pulsed emission of the jet creates internal shocks
and since the jet velocity is very high, the jet bow shock and the internal
shocks are heated to high temperatures and should therefore emit X-ray
radiation. In this paper, we investigate in detail the X-ray properties of the
jets in our models. We have focused our study on the total X-ray luminosity and
its temporal variability, the resulting spectra and the spatial distribution of
the emission. Temperature and density maps from our hydrodynamical simulations
with radiative cooling presented in the second paper are used together with
emissivities calculated with the atomic database ATOMDB. The jets in our models
show extended and variable X-ray emission which can be characterized as a sum
of hot and warm components with temperatures that are consistent with
observations of CH Cyg and R Aqr. The X-ray spectra of our model jets show
emission line features which correspond to observed features in the spectra of
CH Cyg. The innermost parts of our pulsed jets show iron line emission in the
6.4 - 6.7 keV range which may explain such emission from the central source in
R Aqr. We conclude that MWC 560 should be detectable with Chandra or
XMM-Newton, and such X-ray observations will provide crucial for understanding
jets in symbiotic stars.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 20:44:13 GMT"
}
] | 2009-06-23T00:00:00 | [
[
"Stute",
"Matthias",
"",
"Jet Propulsion Laboratory,\n California Institute of Technology"
],
[
"Sahai",
"Raghvendra",
"",
"Jet Propulsion Laboratory,\n California Institute of Technology"
]
] |
0704.2241 | Gavin K. Brennen | Gavin K. Brennen and Jiannis K. Pachos | Why should anyone care about computing with anyons? | 22 pages, 13 figures. Some changes to existing sections, several
references added, and a new section on criteria for TQO and TQC in lattice
systems | Proc. R. Soc. A 10.1098/rspa.2007.0026 (2007) | 10.1098/rspa.2007.0026 | null | quant-ph | null | In this article we present a pedagogical introduction of the main ideas and
recent advances in the area of topological quantum computation. We give an
overview of the concept of anyons and their exotic statistics, present various
models that exhibit topological behavior, and we establish their relation to
quantum computation. Possible directions for the physical realization of
topological systems and the detection of anyonic behavior are elaborated.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 19:35:35 GMT"
},
{
"version": "v2",
"created": "Sat, 8 Sep 2007 23:45:07 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Brennen",
"Gavin K.",
""
],
[
"Pachos",
"Jiannis K.",
""
]
] |
0704.2242 | Patricia Goncalves | Patricia Goncalves, Claudio Landim, Cristina Toninelli | Hydrodynamic Limit for a Particle System with degenerate rates | 26 pages, 3 figures | null | null | null | math.PR | null | We study the hydrodynamic limit for some conservative particle systems with
degenerate rates, namely with nearest neighbor exchange rates which vanish for
certain configurations. These models belong to the class of {\sl kinetically
constrained lattice gases} (KCLG) which have been introduced and intensively
studied in physics literature as simple models for the liquid/glass transition.
Due to the degeneracy of rates for KCLG there exists {\sl blocked
configurations} which do not evolve under the dynamics and in general the
hyperplanes of configurations with a fixed number of particles can be
decomposed into different irreducible sets. As a consequence, both the Entropy
and Relative Entropy method cannot be straightforwardly applied to prove the
hydrodynamic limit. In particular, some care should be put when proving the One
and Two block Lemmas which guarantee local convergence to equilibrium. We show
that, for initial profiles smooth enough and bounded away from zero and one,
the macroscopic density profile for our KCLG evolves under the diffusive time
scaling according to the porous medium equation. Then we prove the same result
for more general profiles for a slightly perturbed dynamics obtained by adding
jumps of the Symmetric Simple Exclusion. The role of the latter is to remove
the degeneracy of rates and at the same time they are properly slowed down in
order not to change the macroscopic behavior. The equilibrium fluctuations and
the magnitude of the spectral gap for this perturbed model are also obtained.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 22:03:07 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Goncalves",
"Patricia",
""
],
[
"Landim",
"Claudio",
""
],
[
"Toninelli",
"Cristina",
""
]
] |
0704.2243 | Clifford M. Will | Thomas Mitchell and Clifford M. Will (Washington University, St.
Louis) | Post-Newtonian gravitational radiation and equations of motion via
direct integration of the relaxed Einstein equations. V. Evidence for the
strong equivalence principle to second post-Newtonian order | 14 pages, submitted to Phys. Rev. D; small changes to coincide with
published version | Phys.Rev.D75:124025,2007 | 10.1103/PhysRevD.75.124025 | null | gr-qc | null | Using post-Newtonian equations of motion for fluid bodies valid to the second
post-Newtonian order, we derive the equations of motion for binary systems with
finite-sized, non-spinning but arbitrarily shaped bodies. In particular we
study the contributions of the internal structure of the bodies (such as
self-gravity) that would diverge if the size of the bodies were to shrink to
zero. Using a set of virial relations accurate to the first post-Newtonian
order that reflect the stationarity of each body, and redefining the masses to
include 1PN and 2PN self-gravity terms, we demonstrate the complete
cancellation of a class of potentially divergent, structure-dependent terms
that scale as s^{-1} and s^{-5/2}, where s is the characteristic size of the
bodies. This is further evidence of the Strong Equivalence Principle, and
supports the use of post-Newtonian approximations to derive equations of motion
for strong-field bodies such as neutron stars and black holes. This extends
earlier work done by Kopeikin.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 21:51:04 GMT"
},
{
"version": "v2",
"created": "Tue, 17 Jul 2007 13:48:45 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Mitchell",
"Thomas",
"",
"Washington University, St.\n Louis"
],
[
"Will",
"Clifford M.",
"",
"Washington University, St.\n Louis"
]
] |
0704.2244 | Erhan Bayraktar | Erhan Bayraktar, Virginia R. Young | Proving Regularity of the Minimal Probability of Ruin via a Game of
Stopping and Control | null | null | null | null | q-fin.PM math.OC math.PR q-fin.RM | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We reveal an interesting convex duality relationship between two problems:
(a) minimizing the probability of lifetime ruin when the rate of consumption is
stochastic and when the individual can invest in a Black-Scholes financial
market; (b) a controller-and-stopper problem, in which the controller controls
the drift and volatility of a process in order to maximize a running reward
based on that process, and the stopper chooses the time to stop the running
reward and rewards the controller a final amount at that time. Our primary goal
is to show that the minimal probability of ruin, whose stochastic
representation does not have a classical form as does the utility maximization
problem (i.e., the objective's dependence on the initial values of the state
variables is implicit), is the unique classical solution of its
Hamilton-Jacobi-Bellman (HJB) equation, which is a non-linear boundary-value
problem. We establish our goal by exploiting the convex duality relationship
between (a) and (b).
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 21:51:33 GMT"
},
{
"version": "v10",
"created": "Wed, 11 Nov 2009 20:47:20 GMT"
},
{
"version": "v11",
"created": "Sun, 4 Apr 2010 03:53:40 GMT"
},
{
"version": "v12",
"created": "Sun, 22 Aug 2010 19:21:10 GMT"
},
{
"version": "v13",
"created": "Fri, 27 Aug 2010 14:43:53 GMT"
},
{
"version": "v2",
"created": "Sat, 19 Jan 2008 18:11:05 GMT"
},
{
"version": "v3",
"created": "Tue, 29 Jul 2008 19:54:19 GMT"
},
{
"version": "v4",
"created": "Fri, 7 Nov 2008 04:17:12 GMT"
},
{
"version": "v5",
"created": "Sun, 9 Nov 2008 13:13:51 GMT"
},
{
"version": "v6",
"created": "Thu, 16 Apr 2009 20:45:29 GMT"
},
{
"version": "v7",
"created": "Tue, 2 Jun 2009 16:20:12 GMT"
},
{
"version": "v8",
"created": "Thu, 9 Jul 2009 16:57:46 GMT"
},
{
"version": "v9",
"created": "Sat, 7 Nov 2009 12:37:24 GMT"
}
] | 2010-08-30T00:00:00 | [
[
"Bayraktar",
"Erhan",
""
],
[
"Young",
"Virginia R.",
""
]
] |
0704.2245 | Natalya A. Zimbovskaya | Natalya A. Zimbovskaya | Fermi-liquid and Fermi surface geometry effects in propagation of low
frequency electromagnetic waves through thin metal films | 9 pages, 5 figures, text added | Phys. Rev. B 76, 075104 (2007) | 10.1103/PhysRevB.76.075104 | null | cond-mat.mtrl-sci cond-mat.str-el | null | In the present work we theoretically analyze the contribution from a
transverse Fermi-liquid collective mode to the transmission of electromagnetic
waves through a thin film of a clean metal in the presence of a strong external
magnetic field. We show that at the appropriate Fermi surface geometry the
transverse Fermi-liquid wave may appear in conduction electrons liquid at
frequencies $\omega$ significantly smaller than the cyclotron frequency of
charge carriers $\Omega$ provided that the mean collision frequency $\tau^{-1}$
is smaller than $\omega.$ Also, we show that in realistic metals size
oscillations in the transmission coefficient associated with the Firmi-liquid
mode may be observable in experiments. Under certain conditions these
oscillations may predominate over the remaining size effects in the
transmission coefficient.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 22:05:32 GMT"
},
{
"version": "v2",
"created": "Tue, 23 Oct 2007 16:52:02 GMT"
}
] | 2007-10-23T00:00:00 | [
[
"Zimbovskaya",
"Natalya A.",
""
]
] |
0704.2246 | Julien Laurat | J. Laurat, C.W. Chou, H. Deng, K.S. Choi, D. Felinto, H. de
Riedmatten, H.J. Kimble | Towards experimental entanglement connection with atomic ensembles in
the single excitation regime | null | New J. Phys. 9, 207 (2007) | 10.1088/1367-2630/9/6/207 | null | quant-ph | null | We present a protocol for performing entanglement connection between pairs of
atomic ensembles in the single excitation regime. Two pairs are prepared in an
asynchronous fashion and then connected via a Bell measurement. The resulting
state of the two remaining ensembles is mapped to photonic modes and a reduced
density matrix is then reconstructed. Our observations confirm for the first
time the creation of coherence between atomic systems that never interacted, a
first step towards entanglement connection, a critical requirement for quantum
networking and long distance quantum communications.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 22:19:57 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Laurat",
"J.",
""
],
[
"Chou",
"C. W.",
""
],
[
"Deng",
"H.",
""
],
[
"Choi",
"K. S.",
""
],
[
"Felinto",
"D.",
""
],
[
"de Riedmatten",
"H.",
""
],
[
"Kimble",
"H. J.",
""
]
] |
0704.2247 | Tomaz Prosen | Tomaz Prosen | Chaos and Complexity of quantum motion | 45 pages, 22 figures, final version, at press in J. Phys. A, special
issue on Quantum Information | null | 10.1088/1751-8113/40/28/S02 | null | quant-ph cond-mat.stat-mech nlin.CD | null | The problem of characterizing complexity of quantum dynamics - in particular
of locally interacting chains of quantum particles - will be reviewed and
discussed from several different perspectives: (i) stability of motion against
external perturbations and decoherence, (ii) efficiency of quantum simulation
in terms of classical computation and entanglement production in operator
spaces, (iii) quantum transport, relaxation to equilibrium and quantum mixing,
and (iv) computation of quantum dynamical entropies. Discussions of all these
criteria will be confronted with the established criteria of integrability or
quantum chaos, and sometimes quite surprising conclusions are found. Some
conjectures and interesting open problems in ergodic theory of the quantum many
problem are suggested.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 22:24:53 GMT"
},
{
"version": "v2",
"created": "Mon, 7 May 2007 16:29:22 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Prosen",
"Tomaz",
""
]
] |
0704.2248 | Edson Iwaki | E. Iwaki, S. O. Juriaans, A. C. Souza Filho | Hyperbolicity of Semigroup Algebras | This article corresponds to the second chapter of the third author
PhD Thesis | null | null | null | math.RA math.GR | null | Let $A$ be a finite dimensional $Q-$algebra and $\Gamma subset A$ a
$Z-$order. We classify those $A$ with the property that $Z^2$ does not embed in
$\mathcal{U}(\Gamma)$. We call this last property the hyperbolic property. We
apply this in the case that $A = KS$ a semigroup algebra with $K = Q$ or $K =
Q(\sqrt{-d})$. In particular, when $KS$ is semi-simple and has no nilpotent
elements, we prove that $S$ is an inverse semigroup which is the disjoint union
of Higman groups and at most one cyclic group $C_n$ with $n \in \{5,8,12\}$.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 22:32:28 GMT"
},
{
"version": "v2",
"created": "Wed, 21 Nov 2007 10:49:07 GMT"
}
] | 2007-11-21T00:00:00 | [
[
"Iwaki",
"E.",
""
],
[
"Juriaans",
"S. O.",
""
],
[
"Filho",
"A. C. Souza",
""
]
] |
0704.2249 | Nathan Smith | Nathan Smith, Ryan J. Foley, and Alexei V. Filippenko | Dust Formation and He II 4686 emission in the Dense Shell of the
Peculiar Type Ib Supernova 2006jc | ApJ, accepted. added some discussion and 2 figures, better title,
conclusions same as previous version. 12 pages, 4 color figs | Astrophys.J.680:568-579,2008 | 10.1086/587860 | null | astro-ph | null | We present evidence for the formation of dust grains in an unusual Type Ib SN
based on late-time spectra of SN 2006jc. The progenitor suffered an LBV-like
outburst just 2 yr earlier, and we propose that the dust formation is a
consequence of the SN blast wave overtaking that LBV-like shell. The key
evidence for dust formation is (a) the appearance of a red/near-IR continuum
source fit by 1600 K graphite grains, and (b) fading of the redshifted sides of
He I emission lines, yielding progressively more asymmetric blueshifted lines
as dust obscures receding material. This provides the strongest case yet for
dust formation in any SN Ib/c. Both developments occurred between 51 and 75 d
after peak, while other SNe observed to form dust did so after a few hundred
days. Geometric considerations indicate that dust formed in the dense swept-up
shell between the forward and reverse shocks, and not in the freely expanding
SN ejecta. Rapid cooling leading to dust formation may have been aided by
extremely high shell densities, as indicated by He I line ratios. The brief
epoch of dust formation is accompanied by He II 4686 emission and enhanced
X-ray emission. These clues suggest that the unusual dust formation in this
object was not due to properties of the SN itself, but instead -- like most
peculiarities of SN 2006jc -- was a consequence of the dense environment
created by an LBV-like eruption 2 yr before the SN.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 23:03:30 GMT"
},
{
"version": "v2",
"created": "Mon, 25 Feb 2008 19:48:36 GMT"
}
] | 2011-03-31T00:00:00 | [
[
"Smith",
"Nathan",
""
],
[
"Foley",
"Ryan J.",
""
],
[
"Filippenko",
"Alexei V.",
""
]
] |
0704.2250 | Alexander Veselov | A.N. Sergeev and A.P. Veselov | Grothendieck rings of basic classical Lie superalgebras | 34 pages, revised version, to appear in Annals of Math | null | null | null | math.RT math.RA | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The Grothendieck rings of finite dimensional representations of the basic
classical Lie superalgebras are explicitly described in terms of the
corresponding generalised root systems. We show that they can be interpreted as
the subrings in the weight group rings invariant under the action of certain
groupoids called Weyl groupoids.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 17:22:03 GMT"
},
{
"version": "v2",
"created": "Wed, 23 Dec 2009 12:29:50 GMT"
}
] | 2009-12-23T00:00:00 | [
[
"Sergeev",
"A. N.",
""
],
[
"Veselov",
"A. P.",
""
]
] |
0704.2251 | Octavian Micu | Roberto Casadio, Alessandro Gruppuso, Benjamin Harms, Octavian Micu | Boundaries and the Casimir effect in non-commutative space-time | 9 pages, 2 figures | Phys.Rev.D76:025016,2007 | 10.1103/PhysRevD.76.025016 | null | hep-th | null | We calculate modifications to the scalar Casimir force between two parallel
plates due to space-time non-commutativity. We devise a heuristic approach to
overcome the difficulties of describing boundaries in non-commutative theories
and predict that boundary corrections are of the same order as non-commutative
volume corrections. Further, both corrections have the form of more
conventional finite surface effects.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 23:27:34 GMT"
},
{
"version": "v2",
"created": "Tue, 22 May 2007 22:11:10 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Casadio",
"Roberto",
""
],
[
"Gruppuso",
"Alessandro",
""
],
[
"Harms",
"Benjamin",
""
],
[
"Micu",
"Octavian",
""
]
] |
0704.2252 | Tomaz Prosen | Tomaz Prosen | Negative differential conductivity in Heisenberg XXZ chain far from
equilibrium | Unpublished notes, written up in February 2004, 5 pages with 3 .eps
figures | null | null | null | quant-ph cond-mat.stat-mech | null | Negative differential conductivity is reported for the far from equilibrium
quantum spin transport in the insulating regime (J_x < J_z) of finite
Heisenberg XXZ spin 1/2 chains. The phenomenon is reproduced analytically for
small chains of N=4 spins and further analyzed numerically, for up to N=16,
using an efficient pure-state simulation with stochastic spin baths.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 23:40:48 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Prosen",
"Tomaz",
""
]
] |
0704.2253 | William T. Reach | William T. Reach, Michael S. Kelley, Mark V. Sykes | A survey of debris trails from short-period comets | accepted by Icarus; figures compressed for astro-ph | 2007, Icarus, 191, 298-322 | 10.1016/j.icarus.2007.03.031 | null | astro-ph | null | We observed 34 comets using the 24 micron camera on the Spitzer Space
Telescope. Each image contains the nucleus and covers at least 10^6 km of each
comet's orbit. Debris trails due to mm-sized or larger particles were found
along the orbits of 27 comets; 4 comets had small-particle dust tails and a
viewing geometry that made debris trails impossible to distinguish; and only 3
had no debris trail despite favorable observing conditions. There are now 30
Jupiter-family comets with known debris trails, of which 22 are reported in
this paper for the first time. The detection rate is >80%, indicating that
debris trails are a generic feature of short-period comets. By comparison to
orbital calculations for particles of a range of sizes ejected over 2 yr prior
to observation, we find that particles comprising 4 debris trails are typically
mm-sized while the remainder of the debris trails require particles larger than
this. The lower-limit masses of the debris trails are typically 10^11 g, and
the median mass loss rate is 2 kg/s. The mass-loss rate in trail particles is
comparable to that inferred from OH production rates and larger than that
inferred from visible-light scattering in comae.
| [
{
"version": "v1",
"created": "Tue, 17 Apr 2007 23:41:42 GMT"
}
] | 2008-04-06T00:00:00 | [
[
"Reach",
"William T.",
""
],
[
"Kelley",
"Michael S.",
""
],
[
"Sykes",
"Mark V.",
""
]
] |
0704.2254 | Richard Green | R.M. Green | Representations of Lie algebras arising from polytopes | Approximately 32 pages, AMSTeX | null | null | null | math.RT math.MG | null | We present an extremely elementary construction of the simple Lie algebras
over the complex numbers in all of their minuscule representations, using the
vertices of various polytopes. The construction itself requires no complicated
combinatorics and essentially no Lie theory other than the definition of a Lie
algebra; in fact, the Lie algebras themselves appear as by-products of the
construction.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 17:37:03 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Green",
"R. M.",
""
]
] |
0704.2255 | E. V. Gotthelf | E. V. Gotthelf and J. P. Halpern (Columbia) | Precise Timing of the X-ray Pulsar 1E 1207.4-5209: A Steady Neutron Star
Weakly Magnetized at Birth | 5 pages, 2 figure, Latex, emulateapj style. Submitted to ApJ Letters | null | 10.1086/520637 | null | astro-ph | null | We analyze all X-ray timing data on 1E 1207.4-5209 in supernova remnant PKS
1209-51/52 gathered in 2000-2005, and find a highly stable rotation with
P=424.130451(4) ms and period derivative of (9.6 +/- 9.4)E-17 s/s. This refutes
previous claims of large timing irregularities in these data. In the dipole
spin-down formalism, the 2-sigma upper limit on period derivative implies an
energy loss rate < 1.5E32 ergs/s, surface magnetic field strength B_p < 3.5E11
G, and characteristic age tau > 24 Myr. This tau exceeds the remnant age by 3
orders of magnitude, requiring that the pulsar was born spinning at its present
period. The X-ray luminosity of 1E 1207.4-5209, L(bol) ~= 2E33 ergs/s at 2 kpc,
exceeds its spin-down energy loss, implying that L(bol) derives from residual
cooling, and perhaps partly from accretion of supernova debris. The upper limit
on B_p is small enough to favor the electron cyclotron model for at least one
of the prominent absorption lines in its soft X-ray spectrum. This is the
second demonstrable case of a pulsar born spinning slowly and with a weak
B-field, after PSR J1852+0040 in Kesteven 79.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 16:14:13 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Gotthelf",
"E. V.",
"",
"Columbia"
],
[
"Halpern",
"J. P.",
"",
"Columbia"
]
] |
0704.2256 | Maciej M. Maska | Anna Gorczyca, Maciej M. Maska, Marcin Mierzejewski | The Friedel oscillations in the presence of transport currents | 5 pages, 3 figures, RevTeX | Phys. Rev. B 76, 165419 (2007) | 10.1103/PhysRevB.76.165419 | null | cond-mat.str-el | null | We investigate the Friedel oscillations in a nanowire coupled to two
macroscopic electrodes of different potentials. We show that the wave-length of
the density oscillations monotonically increases with the bias voltage, whereas
the amplitude and the spatial decay exponent of the oscillations remain intact.
Using the nonequilibrium Keldysh Green functions, we derive an explicit formula
that describes voltage dependence of the wave-length of the Friedel
oscillations.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 01:07:37 GMT"
}
] | 2007-10-18T00:00:00 | [
[
"Gorczyca",
"Anna",
""
],
[
"Maska",
"Maciej M.",
""
],
[
"Mierzejewski",
"Marcin",
""
]
] |
0704.2257 | Yoram Alhassid | S. Schmidt, Y. Alhassid, K. Van Houcke | Effect of a Zeeman field on the superconductor-ferromagnet transition in
metallic grains | 6 pages, 4 figures | Europhys. Lett. 80, 47004 (2007) | 10.1209/0295-5075/80/47004 | null | cond-mat.supr-con cond-mat.mes-hall nucl-th | null | We investigate the competition between pairing correlations and
ferromagnetism in small metallic grains in the presence of a Zeeman field. Our
analysis is based on the universal Hamiltonian, valid in the limit of large
Thouless conductance. We show that the coexistence regime of superconducting
and ferromagnetic correlations can be made experimentally accessible by tuning
an external Zeeman field. We compare the exact solution of the model with a
mean-field theory and find that the latter cannot describe pairing correlations
in the intermediate regime. We also study the occurrence of spin jumps across
the phase boundary separating the superconducting and coexistence regimes.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 01:31:45 GMT"
}
] | 2015-05-13T00:00:00 | [
[
"Schmidt",
"S.",
""
],
[
"Alhassid",
"Y.",
""
],
[
"Van Houcke",
"K.",
""
]
] |
0704.2258 | Stefan Laendner | Andrew McGregor and Olgica Milenkovic | On the Hardness of Approximating Stopping and Trapping Sets in LDPC
Codes | 16 pages, 6 figure, submitted journal version | null | null | null | cs.IT math.IT | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We prove that approximating the size of stopping and trapping sets in Tanner
graphs of linear block codes, and more restrictively, the class of low-density
parity-check (LDPC) codes, is NP-hard. The ramifications of our findings are
that methods used for estimating the height of the error-floor of moderate- and
long-length LDPC codes based on stopping and trapping set enumeration cannot
provide accurate worst-case performance predictions.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 01:49:33 GMT"
},
{
"version": "v2",
"created": "Sun, 3 Aug 2008 04:49:39 GMT"
}
] | 2008-08-03T00:00:00 | [
[
"McGregor",
"Andrew",
""
],
[
"Milenkovic",
"Olgica",
""
]
] |
0704.2259 | Lifeng Lai | Lifeng Lai, Hesham El Gamal and H. Vincent Poor | The Wiretap Channel with Feedback: Encryption over the Channel | Submitted to IEEE Transactions on Information Theory | null | 10.1109/TIT.2008.929914 | null | cs.IT cs.CR math.IT | null | In this work, the critical role of noisy feedback in enhancing the secrecy
capacity of the wiretap channel is established. Unlike previous works, where a
noiseless public discussion channel is used for feedback, the feed-forward and
feedback signals share the same noisy channel in the present model. Quite
interestingly, this noisy feedback model is shown to be more advantageous in
the current setting. More specifically, the discrete memoryless modulo-additive
channel with a full-duplex destination node is considered first, and it is
shown that the judicious use of feedback increases the perfect secrecy capacity
to the capacity of the source-destination channel in the absence of the
wiretapper. In the achievability scheme, the feedback signal corresponds to a
private key, known only to the destination. In the half-duplex scheme, a novel
feedback technique that always achieves a positive perfect secrecy rate (even
when the source-wiretapper channel is less noisy than the source-destination
channel) is proposed. These results hinge on the modulo-additive property of
the channel, which is exploited by the destination to perform encryption over
the channel without revealing its key to the source. Finally, this scheme is
extended to the continuous real valued modulo-$\Lambda$ channel where it is
shown that the perfect secrecy capacity with feedback is also equal to the
capacity in the absence of the wiretapper.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 02:43:40 GMT"
}
] | 2016-11-18T00:00:00 | [
[
"Lai",
"Lifeng",
""
],
[
"Gamal",
"Hesham El",
""
],
[
"Poor",
"H. Vincent",
""
]
] |
0704.2260 | Frederick Matsen IV | Frederick A. Matsen and Mike Steel | Phylogenetic mixtures on a single tree can mimic a tree of another
topology | null | null | null | null | q-bio.PE | null | Phylogenetic mixtures model the inhomogeneous molecular evolution commonly
observed in data. The performance of phylogenetic reconstruction methods where
the underlying data is generated by a mixture model has stimulated considerable
recent debate. Much of the controversy stems from simulations of mixture model
data on a given tree topology for which reconstruction algorithms output a tree
of a different topology; these findings were held up to show the shortcomings
of particular tree reconstruction methods. In so doing, the underlying
assumption was that mixture model data on one topology can be distinguished
from data evolved on an unmixed tree of another topology given enough data and
the ``correct'' method. Here we show that this assumption can be false. For
biologists our results imply that, for example, the combined data from two
genes whose phylogenetic trees differ only in terms of branch lengths can
perfectly fit a tree of a different topology.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 02:46:06 GMT"
},
{
"version": "v2",
"created": "Thu, 7 Jun 2007 23:49:09 GMT"
},
{
"version": "v3",
"created": "Sat, 30 Jun 2007 17:36:20 GMT"
}
] | 2007-06-30T00:00:00 | [
[
"Matsen",
"Frederick A.",
""
],
[
"Steel",
"Mike",
""
]
] |
0704.2261 | Yijian Ouyang | Yijian Ouyang*, Youngki Yoon*, and Jing Guo | Scaling Behaviors of Graphene Nanoribbon FETs: A Three Dimensional
Quantum Simulation Study | *These authors contributed equally to this work. 33 pages, 12
figures. The replacement of this manuscript is because a typo found in
program which changes the quantitative results by factor of 2. The
qualitative features and conclusions are not changed | null | 10.1109/TED.2007.902692 | null | cond-mat.mes-hall | null | The scaling behaviors of graphene nanoribbon (GNR) Schottky barrier
field-effect transistors (SBFETs) are studied by solving the non-equilibrium
Green's function (NEGF) transport equation in an atomistic basis set
self-consistently with a three-dimensional Poisson equation. The armchair edge
GNR channel shares similarities with a zigzag CNT, but it has a different
geometry and quantum confinement boundary condition in the transverse
direction. The results indicate that the I-V characteristics are ambipolar and
strongly depend on the GNR width because the bandgap of the GNR is
approximately inversely proportional to its width, which agrees with recent
experiments. A multiple gate geometry improves immunity to short channel
effects, but it offers smaller improvement than it does for Si MOSFETs in terms
of the on-current and transconductance. Reducing the oxide thickness is more
useful for improving transistor performance than using a high-k gate insulator.
Significant increase of the minimal leakage current is observed when the
channel length is scaled below 10nm because the small effective mass
facilitates strong source-drain tunneling. The GNRFET, therefore, does not
promise extending the ultimate scaling limit of Si MOSFETs. The intrinsic
switching speed of a GNR SBFET, however, is several times faster than that of
Si MOSFETs, which could lead to promising high speed electronics applications,
where the large leakage of GNR SBFETs is of less concern.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 02:53:21 GMT"
},
{
"version": "v2",
"created": "Sun, 27 May 2007 02:25:25 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Ouyang*",
"Yijian",
""
],
[
"Yoon*",
"Youngki",
""
],
[
"Guo",
"Jing",
""
]
] |
0704.2262 | Yin Linsheng | Sunghan Bae, Yong Hu, Linsheng Yin | Irreducible representations and Artin L-functions of quasi-cyclotomic
fields | 17 pages | null | null | null | math.NT | null | We determine all irreducible representations of primary quasi-cyclotomic
fields in this paper. The methods can be applied to determine the irreducible
representations of any quasi-cyclotomic field. We also compute the Artin
L-functions for a class of quasi-cyclotomic fields.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 03:07:51 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Bae",
"Sunghan",
""
],
[
"Hu",
"Yong",
""
],
[
"Yin",
"Linsheng",
""
]
] |
0704.2263 | Chaohong Lee | Chaohong Lee, Elena A. Ostrovskaya, Yuri S. Kivshar | Nonlinearity-assisted quantum tunneling in a matter-wave interferometer | 11 pages, 6 figures, accept for publication in J. Phys. B | J. Phys. B: At. Mol. Opt. Phys. 40, 4235 (2007) | 10.1088/0953-4075/40/21/010 | null | cond-mat.other | null | We investigate the {\em nonlinearity-assisted quantum tunneling} and
formation of nonlinear collective excitations in a matter-wave interferometer,
which is realised by the adiabatic transformation of a double-well potential
into a single-well harmonic trap. In contrast to the linear quantum tunneling
induced by the crossing (or avoided crossing) of neighbouring energy levels,
the quantum tunneling between different nonlinear eigenstates is assisted by
the nonlinear mean-field interaction. When the barrier between the wells
decreases, the mean-field interaction aids quantum tunneling between the ground
and excited nonlinear eigenstates. The resulting {\em non-adiabatic evolution}
depends on the input states. The tunneling process leads to the generation of
dark solitons, and the number of the generated dark solitons is highly
sensitive to the matter-wave nonlinearity. The results of the numerical
simulations of the matter-wave dynamics are successfully interpreted with a
coupled-mode theory for multiple nonlinear eigenstates.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 03:13:05 GMT"
},
{
"version": "v2",
"created": "Mon, 2 Jul 2007 05:40:53 GMT"
},
{
"version": "v3",
"created": "Fri, 12 Oct 2007 04:56:17 GMT"
}
] | 2007-10-25T00:00:00 | [
[
"Lee",
"Chaohong",
""
],
[
"Ostrovskaya",
"Elena A.",
""
],
[
"Kivshar",
"Yuri S.",
""
]
] |
0704.2264 | Gordon F. Royle | Gordon F. Royle | Graphs with chromatic roots in the interval (1,2) | 8 pages | null | null | null | math.CO | null | We present an infinite family of 3-connected non-bipartite graphs with
chromatic roots in the interval (1,2) thus resolving a conjecture of Jackson's
in the negative. In addition, we briefly consider other graph classes that are
conjectured to have no chromatic roots in (1,2).
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 03:35:14 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Royle",
"Gordon F.",
""
]
] |
0704.2265 | Rajan Murgan | Rajan Murgan | Finite-size correction and bulk hole-excitations for special case of an
open XXZ chain with nondiagonal boundary terms at roots of unity | 21 pages, LaTeX, v2: minor changes and 3 references added | JHEP 0705:069,2007 | 10.1088/1126-6708/2007/05/069 | null | hep-th | null | Using our solution for the open spin-1/2 XXZ quantum spin chain with N spins
and two arbitrary boundary parameters at roots of unity, the central charge and
the conformal dimensions for bulk hole excitations are derived from the 1/N
correction to the energy (Casimir energy).
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 03:42:11 GMT"
},
{
"version": "v2",
"created": "Tue, 15 May 2007 20:26:22 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Murgan",
"Rajan",
""
]
] |
0704.2266 | Michael Uleysky | M.V. Budyansky, M.Yu. Uleysky, and S.V. Prants | Dynamical traps and chaotic advection in a meandering jet flow | Double of arXiv:1112.4556 | M.Yu. Uleysky, M.V. Budyansky, and S.V. Prants. Effect of
dynamical traps on chaotic transport in a meandering jet flow. Chaos. V.17.
Is.4 (2007) art. no. 024703 | null | null | nlin.CD physics.ao-ph | null | We continue our study of chaotic mixing and transport of passive particles in
a simple model of a meandering jet flow [Prants, et al, Chaos {\bf 16}, 033117
(2006)]. In the present paper we study and explain phenomenologically a
connection between dynamical, topological, and statistical properties of
chaotic mixing and transport in the model flow in terms of dynamical traps,
singular zones in the phase space where particles may spend arbitrary long but
finite time [Zaslavsky, Phys. D {\bf 168--169}, 292 (2002)]. The transport of
passive particles is described in terms of lengths and durations of zonal
flights which are events between two successive changes of sign of zonal
velocity. Some peculiarities of the respective probability density functions
for short flights are proven to be caused by the so-called rotational-islands
traps connected with the boundaries of resonant islands (including those of the
vortex cores) filled with the particles moving in the same frame. Whereas, the
statistics of long flights can be explained by the influence of the so-called
ballistic-islands traps filled with the particles moving from a frame to frame.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 03:48:37 GMT"
},
{
"version": "v2",
"created": "Thu, 2 Feb 2012 02:21:43 GMT"
}
] | 2012-05-29T00:00:00 | [
[
"Budyansky",
"M. V.",
""
],
[
"Uleysky",
"M. Yu.",
""
],
[
"Prants",
"S. V.",
""
]
] |
0704.2267 | Tao Sun | Tao Sun, Philip B. Allen, David G. Stahnke, Steven D. Jacobsen,
Christopher C. Homes | Infrared Optical Properties of Ferropericlase (Mg1-xFexO): Experiment
and Theory | 17 pages, 6 figures | Phys. Rev. B 77, 134303 (2008) | 10.1103/PhysRevB.77.134303 | null | cond-mat.mtrl-sci | null | The temperature dependence of the reflectance spectra of magnesium oxide
(MgO) and ferropericlase (Mg1-xFexO, for x=0.06 and x=0.27) have been measured
over a wide frequency range (~50 to 32000 cm-1) at 295 and 6 K. The complex
dielectric function has been determined from a Kramers-Kronig analysis of the
reflectance. The spectra of the doped materials resembles pure MgO in the
infrared region, but with much broader resonances. We use a shell model to
calculate the dielectric function of ferropericlase, including both anharmonic
phonon-phonon interactions and disorder scattering. These data are relevant to
understanding the heat conductivity of ferropericlase in the earth's lower
mantle.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 04:33:22 GMT"
}
] | 2008-04-08T00:00:00 | [
[
"Sun",
"Tao",
""
],
[
"Allen",
"Philip B.",
""
],
[
"Stahnke",
"David G.",
""
],
[
"Jacobsen",
"Steven D.",
""
],
[
"Homes",
"Christopher C.",
""
]
] |
0704.2268 | Steffen Roch | V. S. Rabinovich, S. Roch | Essential spectra of difference operators on $\sZ^n$-periodic graphs | null | null | 10.1088/1751-8113/40/33/012 | null | math-ph math.FA math.MP | null | Let $(\cX, \rho)$ be a discrete metric space. We suppose that the group
$\sZ^n$ acts freely on $X$ and that the number of orbits of $X$ with respect to
this action is finite. Then we call $X$ a $\sZ^n$-periodic discrete metric
space. We examine the Fredholm property and essential spectra of band-dominated
operators on $l^p(X)$ where $X$ is a $\sZ^n$-periodic discrete metric space.
Our approach is based on the theory of band-dominated operators on $\sZ^n$ and
their limit operators.
In case $X$ is the set of vertices of a combinatorial graph, the graph
structure defines a Schr\"{o}dinger operator on $l^p(X)$ in a natural way. We
illustrate our approach by determining the essential spectra of Schr\"{o}dinger
operators with slowly oscillating potential both on zig-zag and on hexagonal
graphs, the latter being related to nano-structures.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 15:04:13 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Rabinovich",
"V. S.",
""
],
[
"Roch",
"S.",
""
]
] |
0704.2269 | Zbigniew Ficek | S. Natali and Z. Ficek | Temporal and diffraction effects in entanglement creation in an optical
cavity | Phys. Rev. A75, 042307 (2007) | null | 10.1103/PhysRevA.75.042307 | null | quant-ph | null | A practical scheme for entanglement creation between distant atoms located
inside a single-mode optical cavity is discussed. We show that the degree of
entanglement and the time it takes for the entanglement to reach its optimum
value is a sensitive function the initial conditions and the position of the
atoms inside the cavity mode. It is found that the entangled properties of the
two atoms can readily be extracted from dynamics of a simple two-level system.
Effectively, we engineer two coupled qubits whose the dynamics are analogous to
that of a driven single two-level system. It is found that spatial variations
of the coupling constants actually help to create transient entanglement which
may appear on the time scale much longer than that predicted for the case of
equal coupling constants. When the atoms are initially prepared in an entangled
state, they may remain entangled for all times. We also find that the
entanglement exhibits an interesting phenomenon of diffraction when the the
atoms are located between the nodes and antinodes of the cavity mode. The
diffraction pattern of the entanglement varies with time and we explain this
effect in terms of the quantum property of complementarity, which is manifested
as a tradeoff between the knowledge of energy of the exchanged photon versus
the evolution time of the system.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 04:56:21 GMT"
}
] | 2015-05-13T00:00:00 | [
[
"Natali",
"S.",
""
],
[
"Ficek",
"Z.",
""
]
] |
0704.2270 | Masahiro Suganuma | M. Suganuma (1), Y. Kobayashi (1), N. Okada (1), Y. Yoshii (2), T.
Minezaki (2), T. Aoki (2), K. Enya (3), H. Tomita (2), and S. Koshida (2)
((1) National Astronomical Observatory of Japan, (2) University of Tokyo, (3)
Japan Aerospace Exploration Agency) | The Infrared Cloud Monitor for the MAGNUM Robotic Telescope at Haleakala | 18 pages, 15 figures, 7 tables, accepted for publication in PASP | null | 10.1086/518697 | null | astro-ph | null | We present the most successful infrared cloud monitor for a robotic
telescope. This system was originally developed for the MAGNUM 2-m telescope,
which has been achieving unmanned and automated monitoring observation of
active galactic nuclei at Haleakala on the Hawaiian island of Maui since 2001.
Using a thermal imager and two aspherical mirrors, it at once sees almost the
whole sky at a wavelength of $\lambda\sim 10\mu{\rm m}$. Its outdoor part is
weather-proof and is totally maintenance-free. The images obtained every one or
two minutes are analysed immediately into several ranks of weather condition,
from which our automated observing system not only decides to open or close the
dome, but also selects what types of observations should be done. The whole-sky
data accumulated over four years show that 50$-$60 % of all nights are
photometric, and about 75 % are observable with respect to cloud condition at
Haleakala. Many copies of this system are now used all over the world such as
Mauna Kea in Hawaii, Atacama in Chile, and Okayama and Kiso in Japan.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 07:41:17 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Suganuma",
"M.",
""
],
[
"Kobayashi",
"Y.",
""
],
[
"Okada",
"N.",
""
],
[
"Yoshii",
"Y.",
""
],
[
"Minezaki",
"T.",
""
],
[
"Aoki",
"T.",
""
],
[
"Enya",
"K.",
""
],
[
"Tomita",
"H.",
""
],
[
"Koshida",
"S.",
""
]
] |
0704.2271 | Korinne McDonnell Miss | Korinne E. McDonnell, Alan E. Vaughan and Mark Wardle (Macquarie
University) | A search for OH 6 GHz maser emission towards southern supernova remnants | 2 pages, 1 fig, iaus.cls. To appear in IAU 242, Astrophysical Masers
and Their Environments, eds. J. Chapman & W. Baan | null | 10.1017/S174392130701304X | null | astro-ph | null | OH masers at 1720 MHz have proven to be excellent indicators of interactions
between supernova remnants and molecular clouds. Recent calculations suggest
that the 6049 MHz OH maser line is excited for higher column densities than for
the 1720 MHz line. It is therefore a potentially valuable indicator of
remnant-cloud interaction.
We present preliminary results of a survey using the Parkes Methanol
Multibeam receiver for 6049 MHz and 6035/6030 MHz OH masers towards 36
supernova remnants and 4 fields in the Large and Small Magellanic Clouds. While
no 6049 MHz masers have been found, three new sites of 6035 and 6030 MHz OH
maser emission have been discovered in star-forming regions.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 05:16:44 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"McDonnell",
"Korinne E.",
"",
"Macquarie\n University"
],
[
"Vaughan",
"Alan E.",
"",
"Macquarie\n University"
],
[
"Wardle",
"Mark",
"",
"Macquarie\n University"
]
] |
0704.2272 | Joon Hyeop Lee | Joon Hyeop Lee, Myung Gyoon Lee, Taehyun Kim, Ho Seong Hwang, Changbom
Park, and Yun-Young Choi | The Connection between Star-Forming Galaxies, AGN Host Galaxies and
Early-Type Galaxies in the SDSS | 5 pages with emulateapj, 2 figures, accepted for publication in the
Astrophysical Journal Letters | 2007ApJ...663L..69L | 10.1086/518887 | null | astro-ph | null | We present a study of the connection between star-forming galaxies, AGN host
galaxies, and normal early-type galaxies in the Sloan Digital Sky Survey
(SDSS). Using the SDSS DR5 and DR4plus data, we select our early-type galaxy
sample in the color versus color-gradient space, and we classify the spectral
types of the selected early-type galaxies into normal, star-forming, Seyfert,
and LINER classes, using several spectral line flux ratios. We investigate the
slope in the fundamental space for each class of early-type galaxies and find
that there are obvious differences in the slopes of the fundamental planes
(FPs) among the different classes of early-type galaxies, in the sense that the
slopes for Seyferts and star-forming galaxies are flatter than those for normal
galaxies and LINERs. This may be the first identification of the systematic
variation of the FP slope among the subclasses of early-type galaxies. The
difference in the FP slope might be caused by the difference in the degree of
nonhomology among different classes or by the difference of gas contents in
their merging progenitors. One possible scenario is that the AGN host galaxies
and star-forming galaxies are formed by gas-rich merging and that they may
evolve into normal early-type galaxies after finishing their star formation or
AGN activities.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 05:25:53 GMT"
},
{
"version": "v2",
"created": "Fri, 29 Jun 2007 03:41:53 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Lee",
"Joon Hyeop",
""
],
[
"Lee",
"Myung Gyoon",
""
],
[
"Kim",
"Taehyun",
""
],
[
"Hwang",
"Ho Seong",
""
],
[
"Park",
"Changbom",
""
],
[
"Choi",
"Yun-Young",
""
]
] |
0704.2273 | Pankaj Jain | Pankaj Jain and Subhadip Mitra | Cosmological Symmetry Breaking, Pseudo-scale invariance, Dark Energy and
the Standard Model | 18 pages, no figures | Mod.Phys.Lett.A22:1651-1661,2007 | 10.1142/S0217732307023754 | null | hep-ph astro-ph hep-th | null | The energy density of the universe today may be dominated by the vacuum
energy of a slowly rolling scalar field. Making a quantum expansion around such
a time dependent solution is found to break fundamental symmetries of quantum
field theory. We call this mechanism cosmological symmetry breaking and argue
that it is different from the standard phenomenon of spontaneous symmetry
breaking. We illustrate this with a toy scalar field theory, whose action
displays a U(1) symmetry. We identify a symmetry, called pseudo-scale
invariance, which sets the cosmological constant exactly equal to zero, both in
classical and quantum theory. This symmetry is also broken cosmologically and
leads to a nonzero vacuum or dark energy. The slow roll condition along with
the observed value of dark energy leads to a value of the background scalar
field of the order of Planck mass. We also consider a U(1) gauge symmetry
model. Cosmological symmetry breaking, in this case, leads to a non zero mass
for the vector field. We also show that a cosmologically broken pseudo-scale
invariance can generate a wide range of masses.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 05:36:05 GMT"
},
{
"version": "v2",
"created": "Fri, 22 Jun 2007 11:42:09 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Jain",
"Pankaj",
""
],
[
"Mitra",
"Subhadip",
""
]
] |
0704.2274 | Gregory Eskin | Gregory Eskin (UCLA) James Ralston (UCLA) Masahiro Yamamoto
(University of Tokyo) | Inverse Scattering for Gratings and Wave Guides | 12 pages | Inverse Problems 24 (2008), no. 2, 025008, 12pp | 10.1088/0266-5611/24/2/025008 | null | math.AP math-ph math.MP | null | We consider the problem of unique identification of dielectric coefficients
for gratings and sound speeds for wave guides from scattering data. We prove
that the "propagating modes" given for all frequencies uniquely determine these
coefficients. The gratings may contain conductors as well as dielectrics and
the boundaries of the conductors are also determined by the propagating modes.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 06:17:00 GMT"
}
] | 2015-07-21T00:00:00 | [
[
"Eskin",
"Gregory",
"",
"UCLA"
],
[
"Ralston",
"James",
"",
"UCLA"
],
[
"Yamamoto",
"Masahiro",
"",
"University of Tokyo"
]
] |
0704.2275 | Satoshi Mochizuki | Satoshi Mochizuki | Gersten's conjecture | null | null | null | null | math.KT | null | The purpose of this article is to prove that Gersten's conjecture for a
commutative regular local ring is true. As its applications, we will prove the
vanishing conjecture for certain Chow groups, generator conjecture for certain
$K$-groups and Bloch's formula for absolute case.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 06:38:44 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Mochizuki",
"Satoshi",
""
]
] |
0704.2276 | Hitoshi Murayama | Hitoshi Murayama | Physics Beyond the Standard Model and Dark Matter | Lectures at Les Houches Summer School, Session 86, Particle Physics
and Cosmology: the Fabric of Spacetime, July 31- August 25, 2006 | null | null | null | hep-ph | null | In this lecture note, I discuss why many of us are expecting rich physics at
the TeV scale, drawing analogies from the history of physics in the last
century. Then I review some of the possible candidates of new physics at this
energy scale. I also discuss why we believe much of the matter in the universe
is not atoms (baryons) or compact astronomical objects, and hence requires
physics beyond the standard model. Finally I discuss some of the candidates for
the non-baryonic dark matter.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 07:25:18 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Murayama",
"Hitoshi",
""
]
] |
0704.2277 | Christof Gattringer | Christof Gattringer, Verena Hermann, Markus Limmer | Fermion loop simulation of the lattice Gross-Neveu model | null | Phys.Rev.D76:014503,2007 | 10.1103/PhysRevD.76.014503 | null | hep-lat cond-mat.str-el hep-ph | null | We present a numerical simulation of the Gross-Neveu model on the lattice
using a new representation in terms of fermion loops. In the loop
representation all signs due to Pauli statistics are eliminated completely and
the partition function is a sum over closed loops with only positive weights.
We demonstrate that the new formulation allows to simulate volumes which are
two orders of magnitude larger than those accessible with standard methods.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 06:48:54 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Gattringer",
"Christof",
""
],
[
"Hermann",
"Verena",
""
],
[
"Limmer",
"Markus",
""
]
] |
0704.2278 | Akimichi Takemura | Yo Sheena and Akimichi Takemura | Inference on Eigenvalues of Wishart Distribution Using Asymptotics with
respect to the Dispersion of Population Eigenvalues | null | Sankhya, Vol. 69, No.4, 717-733. (2007) | null | null | math.ST stat.TH | null | In this paper we derive some new and practical results on testing and
interval estimation problems for the population eigenvalues of a Wishart matrix
based on the asymptotic theory for block-wise infinite dispersion of the
population eigenvalues. This new type of asymptotic theory has been developed
by the present authors in Takemura and Sheena (2005) and Sheena and Takemura
(2007a,b) and in these papers it was applied to point estimation problem of
population covariance matrix in a decision theoretic framework. In this paper
we apply it to some testing and interval estimation problems. We show that the
approximation based on this type of asymptotics is generally much better than
the traditional large-sample asymptotics for the problems.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 06:49:07 GMT"
}
] | 2009-01-27T00:00:00 | [
[
"Sheena",
"Yo",
""
],
[
"Takemura",
"Akimichi",
""
]
] |
0704.2279 | Alexey A. Pamyatnykh | J. Daszynska-Daszkiewicz, W. A. Dziembowski, A. A. Pamyatnykh | On the Prospects for Detection and Identification of Low-Frequency
Oscillation Modes in Rotating B Type Stars | 19 pages, 9 figures, Acta Astronomica, in press | null | null | null | astro-ph | null | We study how rotation affects observable amplitudes of high-order g- and
mixed r/g-modes and examine prospects for their detection and identification.
Our formalism, which is described in some detail, relies on a nonadiabatic
generalization of the traditional approximation. Numerical results are
presented for a number of unstable modes in a model of SPB star, at rotation
rates up to 250 km/s. It is shown that rotation has a large effect on mode
visibility in light and in mean radial velocity variations. In most cases, fast
rotation impairs mode detectability of g-modes in light variation, as Townsend
(2003b) has already noted, but it helps detection in radial velocity variation.
The mixed modes, which exist only at sufficiently fast rotation, are also more
easily seen in radial velocity. The amplitude ratios and phase differences are
strongly dependent on the aspect, the rotational velocity and on the mode. The
latter dependence is essential for mode identification.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 06:56:22 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Daszynska-Daszkiewicz",
"J.",
""
],
[
"Dziembowski",
"W. A.",
""
],
[
"Pamyatnykh",
"A. A.",
""
]
] |
0704.2280 | Evgeny Doktorov | Evgeny V. Doktorov, Vassilis M. Rothos and Yuri S. Kivshar | Full-time dynamics of modulational instability in spinor Bose-Einstein
condensates | 6 pages, 2 figures, text slightly extended, a reference added | Physical Review A 76, 013626 (2007) | 10.1103/PhysRevA.76.013626 | null | nlin.SI cond-mat.other | null | We describe the full-time dynamics of modulational instability in F=1 spinor
Bose-Einstein condensates for the case of the integrable three-component model
associated with the matrix nonlinear Schroedinger equation. We obtain an exact
homoclinic solution of this model by employing the dressing method which we
generalize to the case of the higher-rank projectors. This homoclinic solution
describes the development of modulational instability beyond the linear regime,
and we show that the modulational instability demonstrates the reversal
property when the growth of the modulation amplitude is changed by its
exponential decay.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 07:11:33 GMT"
},
{
"version": "v2",
"created": "Thu, 30 Aug 2007 07:40:41 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Doktorov",
"Evgeny V.",
""
],
[
"Rothos",
"Vassilis M.",
""
],
[
"Kivshar",
"Yuri S.",
""
]
] |
0704.2281 | Herbert Weigel | H. Weigel | On the width of collective excitations in chiral soliton models | 8 pages, contribution to the proceedings of YKIS "New frontiers in
QCD", Kyoto, Dec. 2006 | Prog.Theor.Phys.Suppl.168:78-85,2007 | 10.1143/PTPS.168.78 | null | hep-ph | null | In chiral soliton models for baryons the computation of hadronic decay widths
of baryon resonances is a long standing problem. For the three flavor Skyrme
model I present a solution to this problem that satisfies large--$N_C$
consistency conditions. As an application I focus on the hadronic decay of the
$\Theta$ and $\Theta^*$ pentaquarks.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 07:44:29 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Weigel",
"H.",
""
]
] |
0704.2282 | Wim H. Hesselink | W.H. Hesselink and J.C. Hummelen and H.T. Jonkman and H.G. Reker and
G.R. Renardel de Lavalette and M.H. van der Veen | Kekul\'e Cells for Molecular Computation | Also on chemistry (unsaturated polycyclic hydrocarbons) | null | null | null | cs.OH cs.DM | null | The configurations of single and double bonds in polycyclic hydrocarbons are
abstracted as Kekul\'e states of graphs. Sending a so-called soliton over an
open channel between ports (external nodes) of the graph changes the Kekul\'e
state and therewith the set of open channels in the graph. This switching
behaviour is proposed as a basis for molecular computation. The proposal is
highly speculative but may have tremendous impact.
Kekul\'e states with the same boundary behaviour (port assignment) can be
regarded as equivalent. This gives rise to the abstraction of Kekul\'e cells.
The basic theory of Kekul\'e states and Kekul\'e cells is developed here, up to
the classification of Kekul\'e cells with $\leq 4$ ports. To put the theory in
context, we generalize Kekul\'e states to semi-Kekul\'e states, which form the
solutions of a linear system of equations over the field of the bits 0 and 1.
We briefly study so-called omniconjugated graphs, in which every port
assignment of the right signature has a Kekul\'e state. Omniconjugated graphs
may be useful as connectors between computational elements. We finally
investigate some examples with potentially useful switching behaviour.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 07:44:33 GMT"
},
{
"version": "v2",
"created": "Wed, 7 Nov 2007 09:16:22 GMT"
}
] | 2007-11-08T00:00:00 | [
[
"Hesselink",
"W. H.",
""
],
[
"Hummelen",
"J. C.",
""
],
[
"Jonkman",
"H. T.",
""
],
[
"Reker",
"H. G.",
""
],
[
"de Lavalette",
"G. R. Renardel",
""
],
[
"van der Veen",
"M. H.",
""
]
] |
0704.2283 | Thomas Speck | V. Blickle, T. Speck, C. Lutz, U. Seifert, C. Bechinger | The Einstein relation generalized to non-equilibrium | null | Phys. Rev. Lett. 98, 210601 (2007) | 10.1103/PhysRevLett.98.210601 | null | cond-mat.stat-mech cond-mat.soft | null | The Einstein relation connecting the diffusion constant and the mobility is
violated beyond the linear response regime. For a colloidal particle driven
along a periodic potential imposed by laser traps, we test the recent
theoretical generalization of the Einstein relation to the non-equilibrium
regime which involves an integral over measurable velocity correlation
functions.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 08:14:23 GMT"
}
] | 2007-06-20T00:00:00 | [
[
"Blickle",
"V.",
""
],
[
"Speck",
"T.",
""
],
[
"Lutz",
"C.",
""
],
[
"Seifert",
"U.",
""
],
[
"Bechinger",
"C.",
""
]
] |
0704.2284 | Ali Kaya | Erol Ertan, Ali Kaya | Boundary Effects in Local Inflation and Spectrum of Density
Perturbations | 11 pages, 8 figures, revtex4, v4: minor typos corrected, twocolumn
version | Gen.Rel.Grav.40:1511,2008 | 10.1007/s10714-007-0544-x | null | gr-qc astro-ph hep-th | null | We observe that when a local patch in a radiation filled Robertson-Walker
universe inflates by some reason, outside perturbations can enter into the
inflating region. Generally, the physical wavelengths of these perturbations
become larger than the Hubble radius as they cross into the inflating space and
their amplitudes freeze out immediately. It turns out that the corresponding
power spectrum is not scale invariant. Although these perturbations cannot
reach out to a distance inner observer shielded by a de Sitter horizon, they
still indicate a curious boundary effect in local inflationary scenarios.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 08:27:01 GMT"
},
{
"version": "v2",
"created": "Mon, 28 May 2007 15:22:17 GMT"
},
{
"version": "v3",
"created": "Fri, 2 Nov 2007 18:04:59 GMT"
},
{
"version": "v4",
"created": "Tue, 20 Nov 2007 13:04:39 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Ertan",
"Erol",
""
],
[
"Kaya",
"Ali",
""
]
] |
0704.2285 | Nico Cappelluti | N. Cappelluti, H. Boehringer, P. Schuecker, E. Pierpaoli, C. R.
Mullis, I. M. Gioia and J. P. Henry | The 3D soft X-ray cluster-AGN cross-correlation function in the ROSAT
NEP survey | 4 pages, 2 figure, proceedings of the Conference "At the edge of the
Universe", Sintra Portugal, October 2006. To be published on the Astronomical
Society of the Pacific Conference Series (ASPCS) | null | null | null | astro-ph | null | X-ray surveys facilitate investigations of the environment of AGNs. Deep
Chandra observations revealed that the AGNs source surface density rises near
clusters of galaxies. The natural extension of these works is the measurement
of spatial clustering of AGNs around clusters and the investigation of relative
biasing between active galactic nuclei and galaxies near clusters.The major
aims of this work are to obtain a measurement of the correlation length of AGNs
around clusters and a measure of the averaged clustering properties of a
complete sample of AGNs in dense environments. We present the first measurement
of the soft X-ray cluster-AGN cross-correlation function in redshift space
using the data of the ROSAT-NEP survey. The survey covers 9x9 deg^2 around the
North Ecliptic Pole where 442 X-ray sources were detected and almost completely
spectroscopically identified. We detected a >3sigma significant clustering
signal on scales s<50 h70^-1 Mpc. We performed a classical maximum-likelihood
power-law fit to the data and obtained a correlation length s_0=8.7+1.2-0.3
h_70-1 Mpc and a slope gamma=1.7$^+0.2_-0.7 (1sigma errors). This is a strong
evidence that AGNs are good tracers of the large scale structure of the
Universe. Our data were compared to the results obtained by cross-correlating
X-ray clusters and galaxies. We observe, with a large uncertainty, that the
bias factor of AGN is similar to that of galaxies.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 08:33:57 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Cappelluti",
"N.",
""
],
[
"Boehringer",
"H.",
""
],
[
"Schuecker",
"P.",
""
],
[
"Pierpaoli",
"E.",
""
],
[
"Mullis",
"C. R.",
""
],
[
"Gioia",
"I. M.",
""
],
[
"Henry",
"J. P.",
""
]
] |
0704.2286 | Francois Levrier | F. Levrier, E. Falgarone, F. Viallefond | ALMA : Fourier phase analysis made possible | Presented as a poster at the conference "Science with ALMA : A new
era for Astrophysics", 4 pages, to be published in a special issue of
"Astrophysics and Space Science" | null | null | null | astro-ph | null | Fourier phases contain a vast amount of information about structure in direct
space, that most statistical tools never tap into. We address ALMA's ability to
detect and recover this information, using the probability distribution
function (PDF) of phase increments, and the related concepts of phase entropy
and phase structure quantity. We show that ALMA, with its high dynamical range,
is definitely needed to achieve significant detection of phase structure, and
that it will do so even in the presence of a fair amount of atmospheric phase
noise. We also show that ALMA should be able to recover the actual "amount" of
phase structure in the noise-free case, if multiple configurations are used.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 08:36:21 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Levrier",
"F.",
""
],
[
"Falgarone",
"E.",
""
],
[
"Viallefond",
"F.",
""
]
] |
0704.2287 | Dimo Uzunov I. | Dimo I. Uzunov | New fluctuation-driven phase transitions and critical phenomena in
unconventional superconductors | null | Communication E17-2006-128 (JINR-Dubna) | null | Communication E17-2006-128 (JINR-Dubna) | cond-mat.supr-con cond-mat.stat-mech | null | Using the renormalization group method, new type of fluctuation-driven first
order phase transitions and critical phenomena are predicted for certain
classes of ferromagnetic superconductors and superfluids with unconventional
(spin-triplet) Cooper pairing. The problem for the quantum phase transitions at
extremely low and zero temperatures is also discussed. The results can be
applied to a wide class of ferromagnetic superconductive and superfluid
systems, in particular, to itinerant ferromagnets as UGe2 and URhGe.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 08:38:06 GMT"
}
] | 2008-08-08T00:00:00 | [
[
"Uzunov",
"Dimo I.",
""
]
] |
0704.2288 | Jian-Min Wang | J.-M. Wang, Y.-M. Chen, C.-S. Yan, C. Hu and W.-H. Bian | Suppressed star formation in circumnuclear regions in Seyfert galaxies | 1 color figure and 1 table. ApJ Letters in press | null | 10.1086/518807 | null | astro-ph | null | Feedback from black hole activity is widely believed to play a key role in
regulating star formation and black hole growth. A long-standing issue is the
relation between the star formation and fueling the supermassive black holes in
active galactic nuclei (AGNs). We compile a sample of 57 Seyfert galaxies to
tackle this issue. We estimate the surface densities of gas and star formation
rates in circumnuclear regions (CNRs). Comparing with the well-known
Kennicutt-Schmidt (K-S) law, we find that the star formation rates in CNRs of
most Seyfert galaxies are suppressed in this sample. Feedback is suggested to
explain the suppressed star formation rates.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 08:38:33 GMT"
}
] | 2019-08-19T00:00:00 | [
[
"Wang",
"J. -M.",
""
],
[
"Chen",
"Y. -M.",
""
],
[
"Yan",
"C. -S.",
""
],
[
"Hu",
"C.",
""
],
[
"Bian",
"W. -H.",
""
]
] |
0704.2289 | Svante Janson | Svante Janson | Brownian excursion area, Wright's constants in graph enumeration, and
other Brownian areas | Published at http://dx.doi.org/10.1214/07-PS104 in the Probability
Surveys (http://www.i-journals.org/ps/) by the Institute of Mathematical
Statistics (http://www.imstat.org) | Probability Surveys 2007, Vol. 4, 80-145 | 10.1214/07-PS104 | IMS-PS-PS_2007_104 | math.PR | null | This survey is a collection of various results and formulas by different
authors on the areas (integrals) of five related processes, viz.\spacefactor
=1000 Brownian motion, bridge, excursion, meander and double meander; for the
Brownian motion and bridge, which take both positive and negative values, we
consider both the integral of the absolute value and the integral of the
positive (or negative) part. This gives us seven related positive random
variables, for which we study, in particular, formulas for moments and Laplace
transforms; we also give (in many cases) series representations and asymptotics
for density functions and distribution functions. We further study Wright's
constants arising in the asymptotic enumeration of connected graphs; these are
known to be closely connected to the moments of the Brownian excursion area.
The main purpose is to compare the results for these seven Brownian areas by
stating the results in parallel forms; thus emphasizing both the similarities
and the differences. A recurring theme is the Airy function which appears in
slightly different ways in formulas for all seven random variables. We further
want to give explicit relations between the many different similar notations
and definitions that have been used by various authors. There are also some new
results, mainly to fill in gaps left in the literature. Some short proofs are
given, but most proofs are omitted and the reader is instead referred to the
original sources.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 15:26:45 GMT"
},
{
"version": "v2",
"created": "Thu, 10 May 2007 07:58:22 GMT"
},
{
"version": "v3",
"created": "Fri, 11 May 2007 06:06:01 GMT"
}
] | 2011-11-09T00:00:00 | [
[
"Janson",
"Svante",
""
]
] |
0704.2290 | Miroslaw Kozlowski | J.Marciak-Kozlowska, Miroslaw kozlowski | The Heaviside equation for laser heating of the fullerennes | 7 pages | null | null | null | physics.gen-ph | null | In his paper the heating of the fullerenes by ultra-short laser pulses is
investigated. The thermal Heaviside equation is formulated and solved for the
Cauchy initial condition The effective thermal relaxation time is calculated..
Key words: fullerenes, Heaviside thermal equation, effective thermal
relaxation time.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 08:51:28 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Marciak-Kozlowska",
"J.",
""
],
[
"kozlowski",
"Miroslaw",
""
]
] |
0704.2291 | Simon D. M. White | Simon D.M. White | Fundamentalist physics: why Dark Energy is bad for Astronomy | Essay commissioned for publication in Reports on Progress in Physics.
19 pages including 3 figures | Rept.Prog.Phys.70:883-898,2007 | 10.1088/0034-4885/70/6/R01 | null | astro-ph gr-qc hep-ph hep-th | null | Astronomers carry out observations to explore the diverse processes and
objects which populate our Universe. High-energy physicists carry out
experiments to approach the Fundamental Theory underlying space, time and
matter. Dark Energy is a unique link between them, reflecting deep aspects of
the Fundamental Theory, yet apparently accessible only through astronomical
observation. Large sections of the two communities have therefore converged in
support of astronomical projects to constrain Dark Energy. In this essay I
argue that this convergence can be damaging for astronomy. The two communities
have different methodologies and different scientific cultures. By uncritically
adopting the values of an alien system, astronomers risk undermining the
foundations of their own current success and endangering the future vitality of
their field. Dark Energy is undeniably an interesting problem to attack through
astronomical observation, but it is one of many and not necessarily the one
where significant progress is most likely to follow a major investment of
resources.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 08:51:36 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"White",
"Simon D. M.",
""
]
] |
0704.2292 | Bo-Qiang Ma | Zhun Lu, Bo-Qiang Ma, Ivan Schmidt | Double transverse spin asymmetry in the $p^\uparrow\bar{p}^\uparrow$
Drell-Yan process from Sivers functions | 6 latex pages, 2 figures, to appear in PRD | Phys.Rev.D75:094012,2007 | 10.1103/PhysRevD.75.094012 | null | hep-ph | null | We show that the transverse double spin asymmetry (DSA) in the Drell-Yan
process contributed only from the Sivers functions can be picked out by the
weighting function
$\frac{Q_T}{M^2}(\cos(\phi-\phi_{S_1})\cos(\phi-\phi_{S_2})+3\sin(\phi-\phi_{S_1})\sin(\phi-\phi_{S_2}))$.
The asymmetry is proportional to the product of two Sivers functions from each
hadron $f_{1T}^{\perp(1)}\times f_{1T}^{\perp (1)}$. Using two sets of Sivers
functions extracted from the semi-inclusive deeply elastic scattering data at
HERMES, we estimate this asymmetry in the $p^\uparrow\bar{p}^\uparrow$
Drell-Yan process which is possible to be performed in HESR at GSI. The
prediction of DSA in the Drell-Yan process contributed by the function
$g_{1T}(x,\Vec k_T^2)$, which can be extracted by the weighting function
$\frac{Q_T}{M^2}(3\cos(\phi-\phi_{S_1})\cos(\phi-\phi_{S_2})+\sin(\phi-\phi_{S_1})\sin(\phi-\phi_{S_2}))$,
is also given at GSI.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 09:02:33 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Lu",
"Zhun",
""
],
[
"Ma",
"Bo-Qiang",
""
],
[
"Schmidt",
"Ivan",
""
]
] |
0704.2293 | Nico Cappelluti | N. Cappelluti, G. Hasinger, M. Brusa, A. Comastri, G. Zamorani, H.
Boehringer, H. Brunner, F. Civano, A. Finoguenov, F. Fiore, R. Gilli, R. E.
Griffiths, V. Mainieri, I. Matute, T. Miyaji, J. Silverman | X-ray source counts in the COSMOS field | 4 pages, 4 figures, proceeding of the conference "At the edge of the
Universe", Sintra, Portugal, October 2006. To be published on the
Astronomical Society of the Pacific Conference Series (ASPCS) | null | null | null | astro-ph | null | We present the analysis of the source counts in the XMM-COSMOS survey using
data of the first year of XMM-Newton observations. The survey covers ~2 deg^2
within the region of sky bounded by 9^h57.5^m<R.A.<10^h03.5^m;
1^d27.5^m<DEC<2^d57.5^m with a total net integration time of 504 ks. Using a
maximum likelihood algorithm we detected a total of 1390 sources at least in
one band. Using Monte Carlo simulations to estimate the sky coverage we
produced the logN-logS relations. These relations have been then derived in the
0.5--2 keV, 2--10 keV and 5--10 keV energy bands, down to flux limits of
7.2x10^-16 erg cm^-2 s^-1, 4.0x10^-15 erg cm^-2 s^-1 and 9.7x10^-15 erg cm^-2
s^-1, respectively. These relations have been compared to previous X-ray survey
and to the most recent X-ray background model finding an excellent agreement.
The slightly different normalizations observed in the source counts of COSMOS
and previous surveys can be largely explained as a combination of low counting
statistics and cosmic variance introduced by the large scale structure.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 09:06:04 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Cappelluti",
"N.",
""
],
[
"Hasinger",
"G.",
""
],
[
"Brusa",
"M.",
""
],
[
"Comastri",
"A.",
""
],
[
"Zamorani",
"G.",
""
],
[
"Boehringer",
"H.",
""
],
[
"Brunner",
"H.",
""
],
[
"Civano",
"F.",
""
],
[
"Finoguenov",
"A.",
""
],
[
"Fiore",
"F.",
""
],
[
"Gilli",
"R.",
""
],
[
"Griffiths",
"R. E.",
""
],
[
"Mainieri",
"V.",
""
],
[
"Matute",
"I.",
""
],
[
"Miyaji",
"T.",
""
],
[
"Silverman",
"J.",
""
]
] |
0704.2294 | Amel Zaatri | A. Zaatri, J. Provost, G. Berthomieu, P. Morel and T. Corbard | Sensitivity of low degree oscillations to the change in solar abundances | 6 pages, 7 figures. Accepted for publication in Astronomy and
Astrophysics on 11/04/2007 | Astrophys.Space Sci.328:135-138,2010 | 10.1007/s10509-009-0191-7 | null | astro-ph | null | Context. The most recent determination of the solar chemical composition,
using a time-dependent, 3D hydrodynamical model of the solar atmosphere,
exhibits a significant decrease of C, N, O abundances compared to their
previous values. Solar models that use these new abundances are not consistent
with helioseismological determinations of the sound speed profile, the surface
helium abundance and the convection zone depth. Aims. We investigate the effect
of changes of solar abundances on low degree p-mode and g-mode characteristics
which are strong constraints of the solar core. We consider particularly the
increase of neon abundance in the new solar mixture in order to reduce the
discrepancy between models using new abundances and helioseismology. Methods.
The observational determinations of solar frequencies from the GOLF instrument
are used to test solar models computed with different chemical compositions. We
consider in particular the normalized small frequency spacings in the low
degree p-mode frequency range. Results. Low-degree small frequency spacings are
very sensitive to changes in the heavy-element abundances, notably neon. We
show that by considering all the seismic constraints, including the small
frequency spacings, a rather large increase of neon abundance by about (0.5 +/-
0.05)dex can be a good solution to the discrepancy between solar models that
use new abundances and low degree helioseismology, subject to adjusting
slightly the solar age and the highest abundances. We also show that the change
in solar abundances, notably neon, considerably affects g-mode frequencies,
with relative frequency differences between the old and the new models higher
than 1.5%
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 09:08:22 GMT"
},
{
"version": "v2",
"created": "Sun, 22 Apr 2007 09:25:02 GMT"
}
] | 2011-03-28T00:00:00 | [
[
"Zaatri",
"A.",
""
],
[
"Provost",
"J.",
""
],
[
"Berthomieu",
"G.",
""
],
[
"Morel",
"P.",
""
],
[
"Corbard",
"T.",
""
]
] |
0704.2295 | Hassan Jameel | Hassan Jameel, Heejo Lee and Sungyoung Lee | Using Image Attributes for Human Identification Protocols | 24 pages, 8 figures | null | null | null | cs.CR | null | A secure human identification protocol aims at authenticating human users to
a remote server when even the users' inputs are not hidden from an adversary.
Recently, the authors proposed a human identification protocol in the RSA
Conference 2007, which is loosely based on the ability of humans to efficiently
process an image. The advantage being that an automated adversary is not
effective in attacking the protocol without human assistance. This paper
extends that work by trying to solve some of the open problems. First, we
analyze the complexity of defeating the proposed protocols by quantifying the
workload of a human adversary. Secondly, we propose a new construction based on
textual CAPTCHAs (Reverse Turing Tests) in order to make the generation of
automated challenges easier. We also present a brief experiment involving real
human users to find out the number of possible attributes in a given image and
give some guidelines for the selection of challenge questions based on the
results. Finally, we analyze the previously proposed protocol in detail for the
relationship between the secrets. Our results show that we can construct human
identification protocols based on image evaluation with reasonably
``quantified'' security guarantees based on our model.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 09:13:43 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Jameel",
"Hassan",
""
],
[
"Lee",
"Heejo",
""
],
[
"Lee",
"Sungyoung",
""
]
] |
0704.2296 | Michael R. Pennington | R. Williams, C. S. Fischer, M. R. Pennington | Extracting the ${\bar q}q$ condensate for light quarks beyond the chiral
limit in models of QCD | 12 pages, 15 figures | null | null | DCPT/07/26, IPPP/07/13 | hep-ph | null | It has recently been suggested \cite{Chang:2006bm} that a reliable and
unambiguous definition of the non-perturbative massive quark condensate could
be provided by considering a non positive-definite class of solutions to the
Schwinger Dyson Equation for the quark propagator. In this paper we show that
this definition is incomplete without considering a third class of solutions.
Indeed, studying these three classes reveals a degeneracy of possible
condensate definitions leading to a whole range of values. However, we show
that the {\it physical} condensate may in fact be extracted by simple fitting
to the Operator Product Expansion, a procedure which is stabilised by
considering the three classes of solution together. We find that for current
quark masses in the range from zero to 25 MeV or so (defined at a scale of 2
GeV in the $\bar{MS}$ scheme), the dynamically generated condensate increases
from the chiral limit in a wide range of phenomenologically successful models
of the confining QCD interaction. Lastly, the role of a fourth class of noded
solutions is briefly discussed.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 09:16:21 GMT"
}
] | 2007-05-23T00:00:00 | [
[
"Williams",
"R.",
""
],
[
"Fischer",
"C. S.",
""
],
[
"Pennington",
"M. R.",
""
]
] |
0704.2297 | Gong Zhe-Xuan | Wen-Xing Yang and Zhe-Xuan Gong | Efficient scheme for one-way quantum computing in thermal cavities | 6 pages, 3 figures | International Journal of Theoretical Physics, Volume 47, Number
11, 2997-3004 (2008) | 10.1007/s10773-008-9734-x | null | quant-ph | null | We propose a practical scheme for one-way quantum computing based on
efficient generation of 2D cluster state in thermal cavities. We achieve a
controlled-phase gate that is neither sensitive to cavity decay nor to thermal
field by adding a strong classical field to the two-level atoms. We show that a
2D cluster state can be generated directly by making every two atoms collide in
an array of cavities, with numerically calculated parameters and appropriate
operation sequence that can be easily achieved in practical Cavity QED
experiments. Based on a generated cluster state in Box$^{(4)}$ configuration,
we then implement Grover's search algorithm for four database elements in a
very simple way as an example of one-way quantum computing.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 09:23:08 GMT"
}
] | 2011-02-09T00:00:00 | [
[
"Yang",
"Wen-Xing",
""
],
[
"Gong",
"Zhe-Xuan",
""
]
] |
0704.2298 | Tao Wang | Tower Wang | Probing Alpha-Vacua of Black Holes in LHC | 14 pages, 8 eps figures, improved substantially | null | null | USTC-ICTS-07-02 | hep-th hep-ph | null | Motivated by the idea of alpha-vacua in Schwarzschild spacetime, we studied
the deformed spectrum of Hawking radiation. Such a deformation would leave
signatures on the small black hole evaporation in LHC because their vacuum
deviates from the Unruh state.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 13:31:08 GMT"
},
{
"version": "v2",
"created": "Fri, 25 May 2007 12:04:47 GMT"
},
{
"version": "v3",
"created": "Tue, 30 Oct 2007 01:26:23 GMT"
}
] | 2007-10-30T00:00:00 | [
[
"Wang",
"Tower",
""
]
] |
0704.2299 | Michael Mayle | Michael Mayle, Bernd Hezel, Igor Lesanovsky and Peter Schmelcher | One-dimensional Rydberg Gas in a Magnetoelectric Trap | 4 pages, 2 figures | Phys. Rev. Lett. 99, 113004 (2007) | 10.1103/PhysRevLett.99.113004 | null | physics.atom-ph | null | We study the quantum properties of Rydberg atoms in a magnetic
Ioffe-Pritchard trap which is superimposed by a homogeneous electric field.
Trapped Rydberg atoms can be created in long-lived electronic states exhibiting
a permanent electric dipole moment of several hundred Debye. The resulting
dipole-dipole interaction in conjunction with the radial confinement is
demonstrated to give rise to an effectively one-dimensional ultracold Rydberg
gas with a macroscopic interparticle distance. We derive analytical expressions
for the electric dipole moment and the critical linear density of Rydberg
atoms.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 09:29:15 GMT"
},
{
"version": "v2",
"created": "Wed, 6 Jun 2007 13:43:43 GMT"
},
{
"version": "v3",
"created": "Mon, 17 Sep 2007 08:43:11 GMT"
}
] | 2007-09-17T00:00:00 | [
[
"Mayle",
"Michael",
""
],
[
"Hezel",
"Bernd",
""
],
[
"Lesanovsky",
"Igor",
""
],
[
"Schmelcher",
"Peter",
""
]
] |
0704.2300 | Vladan Mlinar | V. Mlinar and F. M. Peeters | Optical properties of (In,Ga)As capped InAs quantum dots grown on [11k]
substrates | null | null | 10.1063/1.2753745 | null | cond-mat.mtrl-sci | null | Using three-dimensional k.p calculation including strain and
piezoelectricity, we showed that the size of the quantum dot (QD) in the growth
direction determines the influence of the (In,Ga)As capping layer on the
optical properties of [11k] grown InAs QDs, where k=1,2,3. For flat dots,
increase of In concentration in the capping layer leads to a decrease of the
transition energy, as is the case of [001] grown QDs, whereas for large dots an
increase of the In concentration in the capping layer is followed by an
increase of the transition energy up to a critical concentration of In, after
which the optical transition energy starts to decrease.
| [
{
"version": "v1",
"created": "Wed, 18 Apr 2007 10:35:45 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Mlinar",
"V.",
""
],
[
"Peeters",
"F. M.",
""
]
] |
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