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list | update_date
timestamp[s] | authors_parsed
sequence |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
0708.1149 | Maura McLaughlin | M. A. McLaughlin, N. Rea, B. M. Gaensler, S. Chatterjee, F. Camilo, M.
Kramer, D. R. Lorimer, A. G. Lyne, G. L. Israel and A. Possenti | Discovery of Pulsations and a Possible Spectral Feature in the X-ray
Emission from Rotating Radio Transient J1819-1458 | 5 figures, accepted by ApJ | null | 10.1086/522335 | null | astro-ph | null | PSR J1819-1458 is a rotating radio transient (RRAT) source with an inferred
surface dipole magnetic field strength of 5e13 G and a 4.26-s spin period. We
present XMM-Newton observations of the X-ray counterpart of this source, CXOU
J181939.1-145804, in which we identify pulsations and a possible spectral
feature. The X-ray pulsations are at the period predicted by the radio
ephemeris, providing an unambiguous identification with the radio source and
confirmation of its neutron star nature. The X-ray pulse has a 0.3-5 keV pulsed
fraction of 34% and is aligned with the expected phase of the radio pulse. The
X-ray spectrum is fit well by an absorbed blackbody with kT = 0.14 keV with the
addition of an absorption feature at 1 keV, with total absorbed flux of 1.5e-13
ergs/cm^2/s (0.3-5 keV). This absorption feature is well modeled by a Gaussian
or resonant cyclotron scattering model, but its significance is dependent on
the choice of continuum model. We find no evidence for any X-ray bursts or
aperiodic variability on timescales of 6 ms to the duration of the observation
and can place the most stringent limit to date of < 3e-9 ergs/cm^2/s on the
absorbed 0.3-5 keV flux of any bursts.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 19:53:02 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"McLaughlin",
"M. A.",
""
],
[
"Rea",
"N.",
""
],
[
"Gaensler",
"B. M.",
""
],
[
"Chatterjee",
"S.",
""
],
[
"Camilo",
"F.",
""
],
[
"Kramer",
"M.",
""
],
[
"Lorimer",
"D. R.",
""
],
[
"Lyne",
"A. G.",
""
],
[
"Israel",
"G. L.",
""
],
[
"Possenti",
"A.",
""
]
] |
0708.1150 | Marko Antonio Rodriguez | Marko A. Rodriguez, Johah Bollen, Herbert Van de Sompel | A Practical Ontology for the Large-Scale Modeling of Scholarly Artifacts
and their Usage | null | Proceedings of the IEEE/ACM Joint Conference on Digital Libraries
(JCDL'07), pp. 278-287, 2007 | 10.1145/1255175.1255229 | null | cs.DL cs.AI | null | The large-scale analysis of scholarly artifact usage is constrained primarily
by current practices in usage data archiving, privacy issues concerned with the
dissemination of usage data, and the lack of a practical ontology for modeling
the usage domain. As a remedy to the third constraint, this article presents a
scholarly ontology that was engineered to represent those classes for which
large-scale bibliographic and usage data exists, supports usage research, and
whose instantiation is scalable to the order of 50 million articles along with
their associated artifacts (e.g. authors and journals) and an accompanying 1
billion usage events. The real world instantiation of the presented abstract
ontology is a semantic network model of the scholarly community which lends the
scholarly process to statistical analysis and computational support. We present
the ontology, discuss its instantiation, and provide some example inference
rules for calculating various scholarly artifact metrics.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 17:06:55 GMT"
}
] | 2007-08-09T00:00:00 | [
[
"Rodriguez",
"Marko A.",
""
],
[
"Bollen",
"Johah",
""
],
[
"Van de Sompel",
"Herbert",
""
]
] |
0708.1151 | Michael A. Soloviev | Michael A. Soloviev (Lebedev Physical Institute) | Noncommutativity and theta-locality | LaTeX, 17 pages, no figures; minor changes to agree with published
version | J.Phys.A40:14593-14604,2007 | 10.1088/1751-8113/40/48/020 | FIAN-TD/2007-17 | hep-th math-ph math.MP math.QA | null | In this paper, we introduce the condition of theta-locality which can be used
as a substitute for microcausality in quantum field theory on noncommutative
spacetime. This condition is closely related to the asymptotic commutativity
which was previously used in nonlocal QFT. Heuristically, it means that the
commutator of observables behaves at large spacelike separation like
$\exp(-|x-y|^2/\theta)$, where $\theta$ is the noncommutativity parameter. The
rigorous formulation given in the paper implies averaging fields with suitable
test functions. We define a test function space which most closely corresponds
to the Moyal star product and prove that this space is a topological algebra
under the star product. As an example, we consider the simplest normal ordered
monomial $:\phi\star\phi:$ and show that it obeys the theta-locality condition.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 17:04:30 GMT"
},
{
"version": "v2",
"created": "Thu, 7 Feb 2008 15:53:19 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Soloviev",
"Michael A.",
"",
"Lebedev Physical Institute"
]
] |
0708.1152 | Dilip G. Banhatti Dr. | V. K. Kapahi, D. G. Banhatti | Luminosity volume test for compact steep spectrum radio sources | 6 pages, 1 table. Seed for MPhil project on Luminosity volume test
for active galaxies vis-a-vis unified schemes. Paper based on MPhil project
in preparation | null | null | null | astro-ph | null | We apply the V/Vm test to a subsample of compact steep-spectrum sources from
a complete sample of radio sources selected at 2.7 GHz. We find that the <V/Vm>
has a value intermediate between those found for samples of extended
steep-spectrum sources and those of compact flat-spectrum sources. If the
sample is split into two further classes of sources having more steep and less
steep spectra, the <V/Vm> values for these then tally roughly with those found
for the extended steep-spectrum and compact flat-spectrum classes of sources.
Implications of this result are discussed.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 17:23:58 GMT"
}
] | 2007-08-09T00:00:00 | [
[
"Kapahi",
"V. K.",
""
],
[
"Banhatti",
"D. G.",
""
]
] |
0708.1153 | Yuri Obukhov | Yuri N. Obukhov, Friedrich W. Hehl | Electrodynamics of moving magnetoelectric media: variational approach | Revtex, 18 pages, no figures, | Phys.Lett.A371:11-19,2007 | 10.1016/j.physleta.2007.08.026 | null | gr-qc cond-mat.other physics.class-ph | null | Recently, Feigel has predicted a new effect in magnetoelectric media. The
theoretical evaluation of this effect requires a careful analysis of a dynamics
of the moving magnetoelectric medium and, in particular, the derivation of the
energy-momentum of the electromagnetic field in such a medium. Then, one can
proceed with the study of the wave propagation in this medium and derive the
mechanical quantities such as the energy, the momentum, and their fluxes and
the corresponding forces. In this paper, we develop a consistent
general-relativistic variational approach to the moving dielectric and magnetic
medium with and without magnetoelectric properties. The old experiments in
which the light pressure was measured in fluids are reanalysed in our new
framework.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 18:07:21 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Obukhov",
"Yuri N.",
""
],
[
"Hehl",
"Friedrich W.",
""
]
] |
0708.1154 | Jean Alexandre | Jean Alexandre, Nick E. Mavromatos and Dylan Tanner | Antisymmetric-Tensor and Electromagnetic effects in an
alpha'-non-perturbative Four-Dimensional String Cosmology | null | NewJ.Phys.10:033033,2008 | 10.1088/1367-2630/10/3/033033 | null | hep-th gr-qc hep-ph | null | Starting from an exact (in the Regge slope alpha') functional method for a
bosonic stringy sigma-model, we investigate four-dimensional cosmological
string solutions in graviton, dilaton and antisymmetric tensor backgrounds,
compatible with world-sheet conformal invariance, and valid beyond perturbative
expansions in powers of alpha'. The antisymmetric tensor field, playing the
role of an axion in the four-dimensional target space time, leads to spatial
anisotropies of the emergent Robertson-Walker expanding Universe, and, upon
coupling the system to the electromagnetic field, it results in non-trivial
optical activity. Some estimates of the corresponding effects are made and
their relevance to current cosmology is briefly discussed.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 18:25:06 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Alexandre",
"Jean",
""
],
[
"Mavromatos",
"Nick E.",
""
],
[
"Tanner",
"Dylan",
""
]
] |
0708.1155 | Vitaly Moroz | Catherine Bandle, Vitaly Moroz and Wolfgang Reichel | "Boundary blowup" type sub-solutions to semilinear elliptic equations
with Hardy potential | 23 pages, 3 figures | J. London Math. Soc. (2) 77 (2008), 503-523 | 10.1112/jlms/jdm104 | null | math.AP | null | Semilinear elliptic equations which give rise to solutions blowing up at the
boundary are perturbed by a Hardy potential. The size of this potential effects
the existence of a certain type of solutions (large solutions): if the
potential is too small, then no large solution exists. The presence of the
Hardy potential requires a new definition of large solutions, following the
pattern of the associated linear problem. Nonexistence and existence results
for different types of solutions will be given. Our considerations are based on
a Phragmen-Lindelof type theorem which enables us to classify the solutions and
sub-solutions according to their behavior near the boundary. Nonexistence
follows from this principle together with the Keller-Osserman upper bound. The
existence proofs rely on sub- and super-solution techniques and on estimates
for the Hardy constant derived in Marcus, Mizel and Pinchover.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 18:35:53 GMT"
},
{
"version": "v2",
"created": "Tue, 14 Aug 2007 00:26:26 GMT"
}
] | 2018-07-31T00:00:00 | [
[
"Bandle",
"Catherine",
""
],
[
"Moroz",
"Vitaly",
""
],
[
"Reichel",
"Wolfgang",
""
]
] |
0708.1156 | Richard Luddy | M. M. Islam, J. Kaspar, R. J. Luddy | pp Elastic Scattering at LHC in a Nucleon-Structure Model | To be published in the Proceedings of the 12th International
Conference on Elastic and Diffractive Scattering, DESY, Hamburg. Presented by
M. M. Islam, May 2007 | null | null | null | hep-ph | null | We predict pp elastic differential cross sections at LHC at c.m. energy 14
TeV and momentum transfer range |t| = 0 - 10 GeV*2 in a nucleon-structure
model. In this model, the nucleon has an outer cloud of quark-antiquark
condensed ground state, an inner shell of topological baryonic charge (r ~
0.44F) probed by the vector meson omega, and a central quark-bag (r ~ 0.2F)
containing valence quarks. We also predict elastic differential cross section
in the Coulomb-hadronic interference region. Large |t| elastic scattering in
this model arises from valence quark-quark scattering, which is taken to be due
to the hard-pomeron (BFKL pomeron with next to leading order corrections). We
present results of taking into account multiple hard-pomeron exchanges, i.e.
unitarity corrections. Finally, we compare our prediction of pp elastic
differential cross section at LHC with the predictions of various other models.
Precise measurement of pp elastic differential cross section at LHC by the
TOTEM group in the |t| region 0 - 5 GeV*2 will be able to distinguish between
these models.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 20:32:19 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Islam",
"M. M.",
""
],
[
"Kaspar",
"J.",
""
],
[
"Luddy",
"R. J.",
""
]
] |
0708.1157 | Roy H. Goodman | Roy H. Goodman and Michael I. Weinstein | Stability and instability of nonlinear defect states in the coupled mode
equations -- analytical and numerical study | 40 pages, 37 figures including subfigures, added references | null | 10.1016/j.physd.2008.04.009 | null | nlin.PS physics.optics | null | Coupled backward and forward wave amplitudes of an electromagnetic field
propagating in a periodic and nonlinear medium at Bragg resonance are governed
by the nonlinear coupled mode equations (NLCME). This system of PDEs, similar
in structure to the Dirac equations, has gap soliton solutions that travel at
any speed between 0 and the speed of light. A recently considered strategy for
spatial trapping or capture of gap optical soliton light pulses is based on the
appropriate design of localized defects in the periodic structure. Localized
defects in the periodic structure give rise to defect modes, which persist as
{\it nonlinear defect modes} as the amplitude is increased. Soliton trapping is
the transfer of incoming soliton energy to {\it nonlinear} defect modes. To
serve as targets for such energy transfer, nonlinear defect modes must be
stable. We therefore investigate the stability of nonlinear defect modes.
Resonance among discrete localized modes and radiation modes plays a role in
the mechanism for stability and instability, in a manner analogous to the
nonlinear Schr\"odinger / Gross-Pitaevskii (NLS/GP) equation. However, the
nature of instabilities and how energy is exchanged among modes is considerably
more complicated than for NLS/GP due, in part, to a continuous spectrum of
radiation modes which is unbounded above and below. In this paper we (a)
establish the instability of branches of nonlinear defect states which, for
vanishing amplitude, have a linearization with eigenvalue embedded within the
continuous spectrum, (b) numerically compute, using Evans function, the
linearized spectrum of nonlinear defect states of an interesting multiparameter
family of defects, and (c) perform direct time-dependent numerical simulations
in which we observe the exchange of energy among discrete and continuum modes.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 20:45:30 GMT"
},
{
"version": "v2",
"created": "Tue, 14 Aug 2007 17:49:46 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Goodman",
"Roy H.",
""
],
[
"Weinstein",
"Michael I.",
""
]
] |
0708.1158 | Ian Heywood | I. Heywood, T.J. O'Brien, S.P.S. Eyres, M.F. Bode, R.J. Davis | V723 Cas (Nova Cassiopeiae 1995): MERLIN observations from 1996 to 2001 | 6 pages, 6 figures | Mon.Not.Roy.Astron.Soc.362:469-474,2005 | 10.1111/j.1365-2966.2005.09328.x | null | astro-ph | null | MERLIN observations of the unusually slow nova V723 Cas are presented. Nine
epochs of 6-cm data between 1996 and 2001 are mapped, showing the initial
expansion and brightening of the radio remnant, the development of structure
and the final decline. A radio light curve is presented and fitted by the
standard Hubble flow model for radio emission from novae in order to determine
the values of various physical parameters for the shell. The model is
consistent with the overall development of the radio emission. Assuming a
distance of 2.39 (+/-0.38) kpc and a shell temperature of 17000 K, the model
yields values for expansion velocity of 414 +/- 0.1 km s^-1 and shell mass of
1.13 +/- 0.04 * 10^-4 Msolar. These values are consistent with those derived
from other observations although the ejected masses are rather higher than
theoretical predictions. The structure of the shell is resolved by MERLIN and
shows that the assumption of spherical symmetry in the standard model is
unlikely to be correct.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 20:54:10 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Heywood",
"I.",
""
],
[
"O'Brien",
"T. J.",
""
],
[
"Eyres",
"S. P. S.",
""
],
[
"Bode",
"M. F.",
""
],
[
"Davis",
"R. J.",
""
]
] |
0708.1159 | Chiu Fan Lee | Alexandra Olaya-Castro, Chiu Fan Lee, Francesca Fassioli Olsen and
Neil F. Johnson | Efficiency of energy transfer in a light-harvesting system under quantum
coherence | Extended version of original paper. 7 pages, 2 figures | Physical Review B 78, 085115 (2008) | 10.1103/PhysRevB.78.085115 | null | quant-ph | null | We investigate the role of quantum coherence in the efficiency of excitation
transfer in a ring-hub arrangement of interacting two-level systems, mimicking
a light-harvesting antenna connected to a reaction center as it is found in
natural photosynthetic systems. By using a quantum jump approach, we
demonstrate that in the presence of quantum coherent energy transfer and
energetic disorder, the efficiency of excitation transfer from the antenna to
the reaction center depends intimately on the quantum superposition properties
of the initial state. In particular, we find that efficiency is sensitive to
symmetric and asymmetric superposition of states in the basis of localized
excitations, indicating that initial state properties can be used as a
efficiency control parameter at low temperatures.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 20:52:02 GMT"
},
{
"version": "v2",
"created": "Tue, 23 Oct 2007 20:32:26 GMT"
},
{
"version": "v3",
"created": "Wed, 16 Apr 2008 14:41:21 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Olaya-Castro",
"Alexandra",
""
],
[
"Lee",
"Chiu Fan",
""
],
[
"Olsen",
"Francesca Fassioli",
""
],
[
"Johnson",
"Neil F.",
""
]
] |
0708.1160 | Bayram Sahin | Bayram Sahin | Quaternion CR-submanifolds of a Locally Conformal Quaternion Kaehler
Manifold | 10 pages | Ege University, Journal of the Faculty of Science, (28), (2005),
81-90 | null | null | math.DG | null | The purpose of the present paper is to study the differential geometric
properties of a quaternion CR-submanifold in a locally conformal quaternion
Kaehler manifold.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 20:00:17 GMT"
},
{
"version": "v2",
"created": "Fri, 10 Aug 2007 02:31:19 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Sahin",
"Bayram",
""
]
] |
0708.1161 | Nikolas Kauer | N. Kauer | A threshold-improved narrow-width approximation for BSM physics | 10 pages, 5 figures, version to appear in JHEP | JHEP0804:055,2008 | 10.1088/1126-6708/2008/04/055 | null | hep-ph | null | A modified narrow-width approximation that allows for O(Gamma/M)-accurate
predictions for resonant particle decay with similar intermediate masses is
proposed and applied to MSSM processes to demonstrate its importance for
searches for particle physics beyond the Standard Model.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 20:00:19 GMT"
},
{
"version": "v2",
"created": "Mon, 14 Apr 2008 20:00:11 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Kauer",
"N.",
""
]
] |
0708.1162 | Aur\'elien A. Fraisse | Aur\'elien A. Fraisse (Princeton), Christophe Ringeval (Louvain),
David N. Spergel (Princeton), Fran\c{c}ois R. Bouchet (IAP) | Small-Angle CMB Temperature Anisotropies Induced by Cosmic Strings | 17 pages, 9 figures. v2: matches published version, minor
clarifications added, typo in Eq. (8) fixed, results unchanged | Phys.Rev.D78:043535,2008 | 10.1103/PhysRevD.78.043535 | null | astro-ph gr-qc hep-th | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We use Nambu-Goto numerical simulations to compute the cosmic microwave
background (CMB) temperature anisotropies induced at arcminute angular scales
by a network of cosmic strings in a Friedmann-Lemaitre-Robertson-Walker (FLRW)
expanding universe. We generate 84 statistically independent maps on a 7.2
degree field of view, which we use to derive basic statistical estimators such
as the one-point distribution and two-point correlation functions. At high
multipoles, the mean angular power spectrum of string-induced CMB temperature
anisotropies can be described by a power law slowly decaying as \ell^{-p}, with
p=0.889 (+0.001,-0.090) (including only systematic errors). Such a behavior
suggests that a nonvanishing string contribution to the overall CMB
anisotropies may become the dominant source of fluctuations at small angular
scales. We therefore discuss how well the temperature gradient magnitude
operator can trace strings in the context of a typical arcminute
diffraction-limited experiment. Including both the thermal and nonlinear
kinetic Sunyaev-Zel'dovich effects, the Ostriker-Vishniac effect, and the
currently favored adiabatic primary anisotropies, we find that, on such a map,
strings should be ``eye visible,'' with at least of order ten distinctive
string features observable on a 7.2 degree gradient map, for tensions U down to
GU \simeq 2 x 10^{-7} (in Planck units). This suggests that, with upcoming
experiments such as the Atacama Cosmology Telescope (ACT), optimal
non-Gaussian, string-devoted statistical estimators applied to small-angle CMB
temperature or gradient maps may put stringent constraints on a possible cosmic
string contribution to the CMB anisotropies.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 23:43:52 GMT"
},
{
"version": "v2",
"created": "Thu, 18 Sep 2008 16:49:36 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Fraisse",
"Aurélien A.",
"",
"Princeton"
],
[
"Ringeval",
"Christophe",
"",
"Louvain"
],
[
"Spergel",
"David N.",
"",
"Princeton"
],
[
"Bouchet",
"François R.",
"",
"IAP"
]
] |
0708.1163 | Nemanja Kaloper | Alberto Iglesias, Nemanja Kaloper, Antonio Padilla and Minjoon Park | How (Not) to Palatini | 18 pages, LaTeX; added references and minor improvements in sec 4 | Phys.Rev.D76:104001,2007 | 10.1103/PhysRevD.76.104001 | null | astro-ph gr-qc hep-ph hep-th | null | We revisit the problem of defining non-minimal gravity in the first order
formalism. Specializing to scalar-tensor theories, which may be disguised as
`higher-derivative' models with the gravitational Lagrangians that depend only
on the Ricci scalar, we show how to recast these theories as Palatini-like
gravities. The correct formulation utilizes the Lagrange multiplier method,
which preserves the canonical structure of the theory, and yields the
conventional metric scalar-tensor gravity. We explain the discrepancies between
the na\"ive Palatini and the Lagrange multiplier approach, showing that the
na\"ive Palatini approach really swaps the theory for another. The differences
disappear only in the limit of ordinary General Relativity, where an accidental
redundancy ensures that the na\"ive Palatini works there. We outline the
correct decoupling limits and the strong coupling regimes. As a corollary we
find that the so-called `Modified Source Gravity' models suffer from strong
coupling problems at very low scales, and hence cannot be a realistic
approximation of our universe. We also comment on a method to decouple the
extra scalar using the chameleon mechanism.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 06:03:54 GMT"
},
{
"version": "v2",
"created": "Mon, 20 Aug 2007 00:07:31 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Iglesias",
"Alberto",
""
],
[
"Kaloper",
"Nemanja",
""
],
[
"Padilla",
"Antonio",
""
],
[
"Park",
"Minjoon",
""
]
] |
0708.1164 | Pavel Kroupa | Pavel Kroupa (AIfA, Bonn) | The IMF of simple and composite populations | 13 pages, to appear in Pathways Through an Eclectic Universe, J. H.
Knapen, T. J. Mahoney, and A. Vazdekis (eds) | null | null | null | astro-ph | null | The combination of a finite time-scale for star formation, rapid early
stellar evolution and rapid stellar-dynamical processes imply that the stellar
IMF cannot be inferred for any star cluster independently of its age (the
Cluster IMF Theorem). The IMF can nevertheless be constrained statistically by
evolving many theoretical populations drawn from one parent distribution and
testing these against observed populations. It follows that all known
well-resolved stellar populations are consistent with having been drawn from
the same parent mass distribution. The IMF Universality Hypothesis therefore
cannot be discarded despite the existence of the Cluster IMF Theorem. This
means that the currently existing star-formation theory fails to describe the
stellar outcome, because it predicts a dependency of the IMF on the physical
boundary conditions not observed. The IGIMF Theorem, however, predicts a
variation of galaxy-wide IMFs in dependence of the galaxy's star-formation rate
even if the IMF Universality Hypothesis is valid. This variation has now been
observed in SDSS galaxy data. Detailed analysis of the binary properties in the
very-low-mass star and brown dwarf (BD) mass regime on the one hand, and in the
stellar regime on the other, shows there to be a discontinuity in the IMF near
0.1Msun such that BDs follow a separate distribution function. Very recent
observations of the stellar population within 1pc of the nucleus of the MW do
suggest a top-heavy IMF, perhaps hinting at a variation of the star-formation
outcome with tidal field and temperature thereby violating the IMF Universality
Hypothesis under these physically extreme conditions. Another violation of this
hypothesis appears to emerge for extremely metal-poor stars such that the
primordial IMF appears to have been depleted in low-mass stars.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 20:04:09 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Kroupa",
"Pavel",
"",
"AIfA, Bonn"
]
] |
0708.1165 | Jean Dolbeault | Jean Dolbeault (CEREMADE), Ari Laptev, Michael Loss | Lieb-Thirring inequalities with improved constants | null | null | null | null | math.AP | null | Following Eden and Foias we obtain a matrix version of a generalised Sobolev
inequality in one-dimension. This allow us to improve on the known estimates of
best constants in Lieb-Thirring inequalities for the sum of the negative
eigenvalues for multi-dimensional Schroedinger operators.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 20:14:18 GMT"
},
{
"version": "v2",
"created": "Fri, 24 Aug 2007 07:21:16 GMT"
}
] | 2011-11-10T00:00:00 | [
[
"Dolbeault",
"Jean",
"",
"CEREMADE"
],
[
"Laptev",
"Ari",
""
],
[
"Loss",
"Michael",
""
]
] |
0708.1166 | Katherine Rhode | Katherine L. Rhode, Stephen E. Zepf, Arunav Kundu, and Aaron N. Larner | Global Properties of the Globular Cluster Systems of Four Spiral
Galaxies | 30 pages, including 14 figures and 13 tables; accepted for
publication in The Astronomical Journal, Oct 2007 issue | Astron.J.134:1403-1418,2007 | 10.1086/521397 | null | astro-ph | null | We present results from a wide-field imaging study of the globular cluster
(GC) systems of a sample of edge-on, Sb-Sc spiral galaxies ~7-20 Mpc away. This
study is part of a larger survey of the ensemble properties of the GC
populations of giant galaxies. We imaged the galaxies in BVR filters with
large-format CCD detectors on the WIYN 3.5-m telescope, to projected radii of
~20-40 kpc. For four galaxies (NGC 2683, NGC 3556, NGC 4157, and NGC 7331), we
quantify the radial distributions of the GC systems and estimate the total
number, luminosity- and mass-normalized specific frequencies (S_N and T), and
blue (metal-poor) fraction of GCs. A fifth galaxy (NGC 3044) was apparently too
distant for us to have detected its GC system. Our S_N for NGC 2683 is 2.5
times smaller than the previously-published value, likely due in part to
reduced contamination from non-GCs. For the spiral galaxies analyzed for the
survey to date, the average number of GCs is 170+/-40 and the weighted mean
values of S_N and T are 0.8+/-0.2 and 1.4+/-0.3. We use the survey data to
derive a relationship between radial exent of the GC system and host galaxy
mass over a factor of 20 in mass. Finally, we confirm the trend, identified in
previous survey papers, of increasing specific frequency of metal-poor GCs with
increasing galaxy mass. We compare the data with predictions from a simple
model and show that carefully quantifying the numbers of metal-poor GCs in
galaxies can constrain the formation redshifts of the GCs and their host
galaxies.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 20:15:25 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Rhode",
"Katherine L.",
""
],
[
"Zepf",
"Stephen E.",
""
],
[
"Kundu",
"Arunav",
""
],
[
"Larner",
"Aaron N.",
""
]
] |
0708.1167 | Maria Stamenova | Maria Stamenova, Tchavdar N. Todorov, Stefano Sanvito | On the Newtonian origin of the spin motive force in ferromagnetic atomic
wires | 5 pages, 7 figures, added figure 7 and text | null | 10.1103/PhysRevB.77.054439 | null | cond-mat.mtrl-sci cond-mat.mes-hall | null | We demonstrate numerically the existence of a spin-motive force acting on
spin-carriers when moving in a time and space dependent internal field. This is
the case of electrons in a one-dimensional wires with a precessing domain wall.
The effect can be explained solely by considering adiabatic dynamics and it is
shown to exist for both classical and quantum systems.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 20:16:44 GMT"
},
{
"version": "v2",
"created": "Mon, 10 Dec 2007 19:37:32 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Stamenova",
"Maria",
""
],
[
"Todorov",
"Tchavdar N.",
""
],
[
"Sanvito",
"Stefano",
""
]
] |
0708.1168 | Davi Rodrigues | Davi C. Rodrigues | Anisotropic Cosmological Constant and the CMB Quadrupole Anomaly | 8 pages, 2 columns, 1 figure. v2: figure improved, added comments on
higher eccentricity powers and references. v3: typos corrected, version to
appear in PRD | Phys.Rev.D77:023534,2008 | 10.1103/PhysRevD.77.023534 | null | astro-ph gr-qc | null | There are evidences that the cosmic microwave background (CMB) large-angle
anomalies imply a departure from statistical isotropy and hence from the
standard cosmological model. We propose a LCDM model extension whose dark
energy component preserves its nondynamical character but wield anisotropic
vacuum pressure. Exact solutions for the cosmological scale factors are
presented, upper bounds for the deformation parameter are evaluated and its
value is estimated considering the elliptical universe proposal to solve the
quadrupole anomaly. This model can be constructed from a Bianchi I cosmology
with cosmological constant from two different ways: i) a straightforward
anisotropic modification of the vacuum pressure consistently with
energy-momentum conservation; ii) a Poisson structure deformation between
canonical momenta such that the dynamics remain invariant under scale factors
rescalings.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 20:46:26 GMT"
},
{
"version": "v2",
"created": "Mon, 10 Dec 2007 19:58:20 GMT"
},
{
"version": "v3",
"created": "Fri, 25 Jan 2008 19:12:19 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Rodrigues",
"Davi C.",
""
]
] |
0708.1169 | Sebastian Szybka | Piotr T. Chru\'sciel, Sebastian J. Szybka | On the Ernst electro-vacuum equations and ergosurfaces | 15 pages, no figures, minor changes | ActaPhys.Polon.B39:59-74,2008 | null | null | gr-qc | null | The question of smoothness at the ergosurface of the space-time metric
constructed out of solutions (E,phi) of the Ernst electro-vacuum equations is
considered. We prove smoothness of those ergosurfaces at which Re(E) provides
the dominant contribution to f=-(Re(E)+|phi|^2) at the zero-level-set of f.
Some partial results are obtained in the remaining cases: in particular we give
examples of leading-order solutions with singular isolated "ergocircles".
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 19:32:19 GMT"
},
{
"version": "v2",
"created": "Sat, 10 Nov 2007 09:51:24 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Chruściel",
"Piotr T.",
""
],
[
"Szybka",
"Sebastian J.",
""
]
] |
0708.1170 | Shuang Jia | S. Jia, Ni Ni, S. L. Bud'ko, P. C. Canfield | Magnetic properties of Gd_xY_{1-x}Fe_2Zn_{20}: dilute, large, $\textbf
{S}$ moments in a nearly ferromagnetic Fermi liquid | null | null | 10.1103/PhysRevB.76.184410 | null | cond-mat.str-el | null | Single crystals of the dilute, rare earth bearing, pseudo-ternary series,
Gd_xY_{1-x}Fe_2Zn_{20} were grown out of Zn-rich solution. Measurements of
magnetization, resistivity and heat capacity on Gd_xY_{1-x}Fe_2Zn_{20} samples
reveal ferromagnetic order of Gd^{3+} local moments across virtually the whole
series ($x \geq 0.02$). The magnetic properties of this series, including the
ferromagnetic ordering, the reduced saturated moments at base temperature, the
deviation of the susceptibilities from Curie-Weiss law and the anomalies in the
resistivity, are understood within the frame work of dilute, $\textbf {S}$
moments (Gd^{3+}) embedded in a nearly ferromagnetic Fermi liquid
(YFe_2Zn_{20}). The s-d model is employed to further explain the variation of
$T_{\mathrm{C}}$ with x as well as the temperature dependences of of the
susceptibilities.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 20:29:18 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Jia",
"S.",
""
],
[
"Ni",
"Ni",
""
],
[
"Bud'ko",
"S. L.",
""
],
[
"Canfield",
"P. C.",
""
]
] |
0708.1171 | Ruslan Sharipov | Ruslan Sharipov | On the spinor structure of the homogeneous and isotropic universe in
closed model | AmSTeX, 25 pages, amsppt style | null | null | null | math.DG | null | The closed homogeneous and isotropic universe is considered. The bundles of
Weyl and Dirac spinors for this universe are explicitly described. Some
explicit formulas for the basic fields and for the connection components in
stereographic and in spherical coordinates are presented.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 20:29:36 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Sharipov",
"Ruslan",
""
]
] |
0708.1172 | Don VandenBerg | Don A. VandenBerg, Bengt Gustafsson, Bengt Edvardsson, Kjell Eriksson,
and Jason Ferguson | A Constraint on Z_\odot from Fits of Isochrones to the Color-Magnitude
Diagram of M67 | 13 pages, including 2 figures and 1 table; accepted (July 2007) for
publication in the Astrophysical Journal Letters | null | 10.1086/521877 | null | astro-ph | null | The mass at which a transition is made between stars that have radiative or
convective cores throughout the core H-burning phase is a fairly sensitive
function of Z (particularly the CNO abundances). As a consequence, the ~4 Gyr,
open cluster M67 provides a constraint on Z_\odot (and the solar heavy-element
mixture) because (i) high-resolution spectroscopy indicates that this system
has virtually the same metal abundances as the Sun, and (ii) its turnoff stars
have masses just above the lower limit for sustained core convection on the
main sequence. In this study, evolutionary tracks and isochrones using the
latest MARCS model atmospheres as boundary conditions have been computed for
0.6-1.4 solar masses on the assumption of a metals mix (implying Z_\odot =
0.0125) based on the solar abundances derived by M. Asplund and collaborators
using 3-D model atmospheres. These calculations do not predict a turnoff gap
where one is observed in M67. No such difficulty is found if the analysis uses
isochrones for Z_\odot = 0.0165, assuming the Grevesse & Sauval (1998) mix of
heavy elements. Our findings, like the inferences from helioseismology,
indicate a problem with the Asplund et al. abundances. However, it is possible
that low-Z models with diffusive processes taken into account will be less
problematic.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 21:03:28 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"VandenBerg",
"Don A.",
""
],
[
"Gustafsson",
"Bengt",
""
],
[
"Edvardsson",
"Bengt",
""
],
[
"Eriksson",
"Kjell",
""
],
[
"Ferguson",
"Jason",
""
]
] |
0708.1173 | Nikolai Rulkov | Nikolai F. Rulkov | A Map-Based Model of the Cardiac Action Potential | 6 pages, 9 figures, submitted to PRE | null | null | null | q-bio.CB | null | A discrete time model that is capable of replicating the basic features of
cardiac cell action potentials is suggested. The paper shows how the map-based
approaches can be used to design highly efficient computational models
(algorithms) that enable large-scale simulations and analysis of discrete
network models of cardiac activity.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 21:04:19 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Rulkov",
"Nikolai F.",
""
]
] |
0708.1174 | Dirk Oliver Theis | Dirk Oliver Theis | On some lower bounds on the number of bicliques needed to cover a
bipartite graph | 6 pages | null | null | null | math.CO | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | The biclique covering number of a bipartite graph G is the minimum number of
complete bipartite subgraphs (bicliques) whose union contains every edge of G.
In this little note we compare three lower bounds on the biclique covering
number: A bound jk(G) proposed by Jukna & Kulikov (Discrete Math. 2009); the
well-known fooling set bound fool(G); the "tensor-power" fooling set bound
fool^\infty(G). We show jk \le fool le fool^\infty \le min_Q (rk Q)^2, where
the minimum is taken over all matrices with a certain zero/nonzero-pattern.
Only the first inequality is really novel, the third one generalizes a result
of Dietzfelbinger, Hromkovi\v{c}, Schnitger (1994).
We also give examples for which fool \ge (rk)^{log_4 6} improving on
Dietzfelbinger et al.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 21:06:24 GMT"
},
{
"version": "v2",
"created": "Mon, 10 Dec 2007 17:08:36 GMT"
},
{
"version": "v3",
"created": "Wed, 2 Apr 2008 18:42:38 GMT"
},
{
"version": "v4",
"created": "Tue, 6 Sep 2011 09:46:27 GMT"
}
] | 2011-09-07T00:00:00 | [
[
"Theis",
"Dirk Oliver",
""
]
] |
0708.1175 | Armen Allahverdyan | Armen E. Allahverdyan and Dominik Janzing | Relating the thermodynamic arrow of time to the causal arrow | 10 pages | null | 10.1088/1742-5468/2008/04/P04001 | null | cond-mat.stat-mech | null | Consider a Hamiltonian system that consists of a slow subsystem S and a fast
subsystem F. The autonomous dynamics of S is driven by an effective
Hamiltonian, but its thermodynamics is unexpected. We show that a well-defined
thermodynamic arrow of time (second law) emerges for S whenever there is a
well-defined causal arrow from S to F and the back-action is negligible. This
is because the back-action of F on S is described by a non-globally Hamiltonian
Born-Oppenheimer term that violates the Liouville theorem, and makes the second
law inapplicable to S. If S and F are mixing, under the causal arrow condition
they are described by microcanonic distributions P(S) and P(S|F). Their
structure supports a causal inference principle proposed recently in machine
learning.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 21:08:26 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Allahverdyan",
"Armen E.",
""
],
[
"Janzing",
"Dominik",
""
]
] |
0708.1176 | Miguel Urbaneja | M.A. Urbaneja, R.-P. Kudritzki and J. Puls | Clumping in the winds of O-type CSPNs | 3 pages, 2 figures, to appear in the workshop proceedings "Clumping
in Hot Star Winds", eds. W.-R. Hamann, A. Feldmeier and L. Oskinova | null | null | null | astro-ph | null | Recent studies of massive O-type stars present clear evidences of
inhomogeneous and clumped winds. O-type (H-rich) central stars of planetary
nebulae (CSPNs) are in some ways the low mass-low luminosity analogous of those
massive stars. In this contribution, we present preliminary results of our
on-going multi-wavelength (FUV, UV and optical) study of the winds of Galactic
CSPNs. Particular emphasis will be given to the clumping factors derived by
means of optical lines (Halpha and HeII4686) and "classic" FUV (and UV) lines.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 21:10:10 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Urbaneja",
"M. A.",
""
],
[
"Kudritzki",
"R. -P.",
""
],
[
"Puls",
"J.",
""
]
] |
0708.1177 | Ian Heywood | I. Heywood, T.J. O'Brien | Simulations and interpretation of the 6-cm MERLIN images of the
classical nova V723 Cas | 11 pages, 15 figures | Mon.Not.Roy.Astron.Soc.379:1453-1463,2007 | 10.1111/j.1365-2966.2007.12027.x | null | astro-ph | null | We compare the predictions of simple models for the radio emission from
classical novae with the MERLIN radio observations of nova V723 Cas (Nova Cas
1995). Spherically symmetric and ellipsoidal radiative transfer models are
implemented in order to generate synthetic emission maps. These are then
convolved with an accurate representation of the uv coverage of MERLIN. The
parameters and geometry of the shell model are based on those returned by
fitting models to the observed light curve. This allows direct comparison of
the model images with the nine 6-cm MERLIN images of V723 Cas. It is found that
the seemingly complex structure (clumping, apparent rotation) evident in the
observations can actually be reproduced with a simple spherical emission model.
The simulations showthat a 24-h track greatly reduces the instrumental effects
and the synthetic radio map is a closer representation of the true (model) sky
brightness distribution. It is clear that interferometric arrays with sparse uv
coverage (e.g. MERLIN, VLBA) will be more prone to these instrumental effects
especially when imaging ring-like objects with time-dependent structure
variations. A modelling approach such as that adopted here is essential when
interpreting observations.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 21:12:20 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Heywood",
"I.",
""
],
[
"O'Brien",
"T. J.",
""
]
] |
0708.1178 | Eugenia Cheng | Eugenia Cheng and Nick Gurski | The periodic table of n-categories for low dimensions I: degenerate
categories and degenerate bicategories | 23 pages, to appear in Streetfest proceedings | null | null | null | math.CT | null | We examine the periodic table of weak n-categories for the low-dimensional
cases. It is widely understood that degenerate categories give rise to monoids,
doubly degenerate bicategories to commutative monoids, and degenerate
bicategories to monoidal categories; however, to understand this correspondence
fully we examine the totalities of such structures together with maps between
them and higher maps between those. Categories naturally form a 2-category
{\bfseries Cat} so we take the full sub-2-category of this whose 0-cells are
the degenerate categories. Monoids naturally form a category, but we regard
this as a discrete 2-category to make the comparison. We show that this
construction does not yield a biequivalence; to get an equivalence we ignore
the natural transformations and consider only the {\it category} of degenerate
categories. A similar situation occurs for degenerate bicategories. The
tricategory of such does not yield an equivalence with monoidal categories; we
must consider only the categories of such structures. For doubly degenerate
bicategories the tricategory of such is not naturally triequivalent to the
category of commutative monoids (regarded as a tricategory). However in this
case considering just the categories does not give an equivalence either; to
get an equivalence we consider the {\it bicategory} of doubly degenerate
bicategories. We conclude with a hypothesis about how the above cases might
generalise for n-fold degenerate n-categories.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 21:13:33 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Cheng",
"Eugenia",
""
],
[
"Gurski",
"Nick",
""
]
] |
0708.1179 | Shuangqing Wei | Shuangqing Wei | Diversity-Multiplexing Tradeoff of Asynchronous Cooperative Diversity in
Wireless Networks | null | null | null | null | cs.IT math.IT | null | Synchronization of relay nodes is an important and critical issue in
exploiting cooperative diversity in wireless networks. In this paper, two
asynchronous cooperative diversity schemes are proposed, namely, distributed
delay diversity and asynchronous space-time coded cooperative diversity
schemes. In terms of the overall diversity-multiplexing (DM) tradeoff function,
we show that the proposed independent coding based distributed delay diversity
and asynchronous space-time coded cooperative diversity schemes achieve the
same performance as the synchronous space-time coded approach which requires an
accurate symbol-level timing synchronization to ensure signals arriving at the
destination from different relay nodes are perfectly synchronized. This
demonstrates diversity order is maintained even at the presence of asynchronism
between relay node. Moreover, when all relay nodes succeed in decoding the
source information, the asynchronous space-time coded approach is capable of
achieving better DM-tradeoff than synchronous schemes and performs equivalently
to transmitting information through a parallel fading channel as far as the
DM-tradeoff is concerned. Our results suggest the benefits of fully exploiting
the space-time degrees of freedom in multiple antenna systems by employing
asynchronous space-time codes even in a frequency flat fading channel. In
addition, it is shown asynchronous space-time coded systems are able to achieve
higher mutual information than synchronous space-time coded systems for any
finite signal-to-noise-ratio (SNR) when properly selected baseband waveforms
are employed.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 21:25:08 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Wei",
"Shuangqing",
""
]
] |
0708.1180 | Christopher Stockdale | Matthew T. Kelley, Christopher J. Stockdale, Kurt W. Weiler,
Christopher L. M. Williams, Nino Panagia, Richard A. Sramek, J. M. Marcaide,
and Schuyler D. Van Dyk | Light Curves of Radio Supernovae | 3 pages, 6 figures Conference Proceedings: "Supernova 1987A: 20 Years
After: Supernovae and Gamma-Ray Bursters" AIP, New York, eds. S. Immler, K.W.
Weiler, and R. McCray | AIPConf.Proc.937:269-271,2007 | 10.1063/1.2803574 | null | astro-ph | null | We present the results from the on-going radio monitoring of recent type II
supernovae (SNe), including SNe 2004et, 2004dj, 2002hh, 2001em, and 2001gd.
Using the Very Large Array to monitor these supernovae, we present their radio
light-curves. From these data we are able to discuss parameterizations and
modeling and make predictions of the nature of the progenitors based on
previous research. Derived mass loss rates assume wind-established
circumstellar medium, shock velocity ~10,000 km/s, wind velocity ~10 km/s, and
CSM Temperature ~10,000 K.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 21:30:23 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Kelley",
"Matthew T.",
""
],
[
"Stockdale",
"Christopher J.",
""
],
[
"Weiler",
"Kurt W.",
""
],
[
"Williams",
"Christopher L. M.",
""
],
[
"Panagia",
"Nino",
""
],
[
"Sramek",
"Richard A.",
""
],
[
"Marcaide",
"J. M.",
""
],
[
"Van Dyk",
"Schuyler D.",
""
]
] |
0708.1181 | Antonina Toropova | A. Toropova, C. A. Marianetti, K. Haule, G. Kotliar | One-Electron Physics of the Actinides | 11 pages, 7 figures | Phys. Rev. B 76, 155126 (2007) | 10.1103/PhysRevB.76.155126 | null | cond-mat.str-el cond-mat.mtrl-sci | null | We present a detailed analysis of the one-electron physics of the actinides.
Various LMTO basis sets are analyzed in order to determine a robust bare
Hamiltonian for the actinides. The hybridization between f- an spd- states is
compared with the f-f hopping in order to understand the Anderson-like and
Hubbard-like contributions to itineracy in the actinides. We show that both
contributions decrease strongly as one move from the light actinides to the
heavy actinides, while the Anderson-like contribution dominates in all cases. A
real-space analysis of the band structure shows that nearest-neighbor hopping
dominates the physics in these materials. Finally, we discuss the implications
of our results to the delocalization transition as function of atomic number
across the actinide series.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 21:38:19 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Toropova",
"A.",
""
],
[
"Marianetti",
"C. A.",
""
],
[
"Haule",
"K.",
""
],
[
"Kotliar",
"G.",
""
]
] |
0708.1182 | Christopher Stockdale | Christopher J. Stockdale, Matthew T. Kelley, Kurt W. Weiler, Nino
Panagia, Richard A. Sramek, J. M. Marcaide, Christopher L. M. Williams, and
Schuyler D. Van Dyk | Recent Type II Radio Supernovae | 5 pages, 2 figures, 1 table Conference Proceedings: "Supernova 1987A:
20 Years After: Supernovae and Gamma-Ray Bursters" AIP, New York, eds. S.
Immler, K.W. Weiler, and R. McCray | AIPConf.Proc.937:264-268,2007 | 10.1063/1.2803573 | null | astro-ph | null | We present the results of radio observations, taken primarily with the Very
Large Array, of Supernovae 1993J, 2001gd, 2001em, 2002hh, 2004dj, and 2004et.
We have fit a parameterized model to the multi-frequency observations of each
supernova. We compare the observed and derived radio properties of these
supernovae by optical classification and discuss the implications.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 21:36:33 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Stockdale",
"Christopher J.",
""
],
[
"Kelley",
"Matthew T.",
""
],
[
"Weiler",
"Kurt W.",
""
],
[
"Panagia",
"Nino",
""
],
[
"Sramek",
"Richard A.",
""
],
[
"Marcaide",
"J. M.",
""
],
[
"Williams",
"Christopher L. M.",
""
],
[
"Van Dyk",
"Schuyler D.",
""
]
] |
0708.1183 | Kentaro Nagamine | Kentaro Nagamine (UNLV) | DLAs and Galaxy Formation | 15 pages, 10 figures. Invited brief review for Modern Physics Letters
A, in press | Mod.Phys.Lett.A22:2413-2427,2007 | 10.1142/S021773230702436X | null | astro-ph | null | Damped Lyman-alpha systems (DLAs) are useful probes of star formation and
galaxy formation at high redshift. We study the physical properties of DLAs and
their relationship to Lyman-break galaxies using cosmological hydrodynamic
simulations based on the concordance Lambda cold dark matter model. Fundamental
statistics such as global neutral hydrogen (HI) mass density, HI column density
distribution function, DLA rate-of-incidence and mean halo mass of DLAs are
reproduced reasonably well by the simulations, but with some deviations that
need to be understood better in the future. We discuss the feedback effects by
supernovae and galactic winds on the DLA distribution. We also compute the
[C_II] emission from neutral gas in high-z galaxies, and make predictions for
the future observations by ALMA and SPICA. Agreement and disagreement between
simulations and observations are discussed, as well as the future directions of
our DLA research.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 21:52:57 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Nagamine",
"Kentaro",
"",
"UNLV"
]
] |
0708.1184 | Eric Chesebro | Eric Chesebro, Jason DeBlois | Trace fields and commensurability of link complements | 29 pages, 9 figures; added emails and affiliations for authors | null | null | null | math.GT | null | This paper investigates the strength of the trace field as a commensurability
invariant of hyperbolic 3-manifolds. We construct an infinite family of
two-component hyperbolic link complements which are pairwise incommensurable
and have the same trace field, and infinitely many 1-cusped finite volume
hyperbolic 3-manifolds with the same property. We also show that the
two-component link complements above have integral traces, but each has a
mutant with a nonintegral trace.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 21:44:37 GMT"
},
{
"version": "v2",
"created": "Wed, 15 Aug 2007 18:26:22 GMT"
}
] | 2007-08-15T00:00:00 | [
[
"Chesebro",
"Eric",
""
],
[
"DeBlois",
"Jason",
""
]
] |
0708.1185 | Nikodem Szpak | Nikodem Szpak | Weighted-$L^\infty$ and pointwise space-time decay estimates for wave
equations with potentials and initial data of low regularity | 31 pages | null | null | null | math-ph math.MP | null | We prove weighted-$L^\infty$ and pointwise space-time decay estimates for
weak solutions of a class of wave equations with time-independent potentials
and subject to initial data, both of low regularity, satisfying given decay
bounds at infinity. The rate of their decay depends on the asymptotic behaviour
of the potential and of the data. The technique is robust enough to treat also
more regular solutions and provides decay estimates for arbitrary derivatives,
provided the potential and the data have sufficient regularity, but it is
restricted to potentials of bounded strength (such that $-\Delta-|V|$ has no
negative eigenvalues).
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 21:46:36 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Szpak",
"Nikodem",
""
]
] |
0708.1186 | Vincent L. Fish | Vincent L. Fish (NRAO), Mark J. Reid (CfA) | Proper Motions of OH Masers and Magnetic Fields in Massive Star-Forming
Regions | 16 pages using emulateapj.cls including 17 figures and 5 tables,
accepted to ApJ | null | 10.1086/522329 | null | astro-ph | null | We present data of proper motions of OH masers in the massive star-forming
regions ON 1, K3-50, and W51 Main/South. OH maser motions in ON 1 are
consistent with expansion at approximately 5 km/s, likely tracing the expanding
ultracompact H II region. Motions in K3-50 are faster and may be indicating the
final stages of OH maser emission in the source, before the OH masers turn off
as the H II region transitions from the ultracompact to the compact phase. W51
South shows indications of aspherical expansion, while motions in W51 Main are
more difficult to interpret. Nevertheless, it appears that the relative
projected separation between W51 Main and W51 South is decreasing,
corresponding to an estimate of enclosed mass of at least 1500 solar masses,
consistent with estimates derived from millimeter-wavelength dust emission. We
confirm the ~20 mG magnetic fields previously seen in W51 Main, which may
represent the upper end of the density range allowable for 1665 MHz maser
emission. Magnetic field strengths and directions, obtained from Zeeman
splitting, in each source are consistent with values obtained in the first
epoch four to nine years ago.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 21:46:37 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Fish",
"Vincent L.",
"",
"NRAO"
],
[
"Reid",
"Mark J.",
"",
"CfA"
]
] |
0708.1187 | Saharian | A. A. Saharian | The generalized Abel-Plana formula with applications to Bessel functions
and Casimir effect | 120 pages | null | null | Preprint ICTP/2007/082 | hep-th math-ph math.GM math.MP quant-ph | null | One of the most efficient methods for the evaluation of the vacuum
expectation values for physical observables in the Casimir effect is based on
using the Abel-Plana summation formula. This enables to derive the renormalized
quantities in a manifestly cutoff independent way and to present them in the
form of strongly convergent integrals. However, applications of the Abel-Plana
formula, in its usual form, are restricted by simple geometries when the
eigenmodes have a simple dependence on quantum numbers. The author generalized
the Abel-Plana formula which essentially enlarges its application range. Based
on this generalization, formulae have been obtained for various types of series
over the zeros of combinations of Bessel functions and for integrals involving
these functions. It has been shown that these results generalize the special
cases existing in literature. Further, the derived summation formulae have been
used to summarize series arising in the direct mode summation approach to the
Casimir effect for spherically and cylindrically symmetric boundaries, for
boundaries moving with uniform proper acceleration, and in various braneworld
scenarios. This allows to extract from the vacuum expectation values of local
physical observables the parts corresponding to the geometry without boundaries
and to present the boundary-induced parts in terms of integrals strongly
convergent for the points away from the boundaries. As a result, the
renormalization procedure for these observables is reduced to the corresponding
procedure for bulks without boundaries. The present paper reviews these
results. We also aim to collect the results on vacuum expectation values for
local physical observables such as the field square and the energy-momentum
tensor in manifolds with boundaries for various bulk and boundary geometries.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 21:49:38 GMT"
}
] | 2007-12-03T00:00:00 | [
[
"Saharian",
"A. A.",
""
]
] |
0708.1188 | Don VandenBerg | Don A. VandenBerg, Bengt Edvardsson, Kjell Eriksson, and Bengt
Gustafsson | On the Use of Blanketed Atmospheres as Boundary Conditions for Stellar
Evolutionary Models | 54 pages, including 20 figures and 3 tables; accepted (July 2007) for
publication in the Astrophysical Journal | null | 10.1086/521600 | null | astro-ph | null | Stellar models have been computed for stars having [Fe/H] = 0.0 and -2.0 to
determine the effects of using boundary conditions derived from the latest
MARCS model atmospheres. The latter were fitted to the interior models at both
the photosphere and at tau = 100, and at least for the 0.8-1.0 solar mass stars
considered here, the resultant evolutionary tracks were found to be nearly
independent of the chosen fitting point. Particular care was taken to treat the
entire star as consistently as possible; i.e., both the interior and atmosphere
codes assumed the same abundances and the same treatment of convection. Tracks
were also computed using either the classical gray T(tau,T_eff) relation or
that derived by Krishna Swamy (1966) to derive the boundary pressure. The
latter predict warmer giant branches (by ~150 K) at solar abundances than those
based on gray or MARCS atmospheres, which happens to be in good agreement with
the inferred temperatures of giants in the open cluster M67 from the latest
(V-K)-T_eff relations. Most of the calculations assumed Z=0.0125 (Asplund et
al.), though a few models were computed for Z=0.0165 (Grevesse & Sauval) to
determine the dependence of the tracks on Z_\odot. Grids of "scaled solar,
differentially corrected" (SDC) atmospheres were also computed to try to
improve upon theoretical MARCS models. When they were used as boundary
conditions, the resultant tracks agreed very well with those based on a
standard scaled-solar (e.g., Krishna Swamy) T(tau,T_eff) relation,
independently of the assumed metal abundance. Fits of isochrones to the C-M
diagram of the [Fe/H] = -2 globular cluster M68 were examined, as was the
possibility that the mixing-length parameter varies with stellar parameters.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 22:22:18 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"VandenBerg",
"Don A.",
""
],
[
"Edvardsson",
"Bengt",
""
],
[
"Eriksson",
"Kjell",
""
],
[
"Gustafsson",
"Bengt",
""
]
] |
0708.1189 | Douglas J. Durian | A.R. Abate, H. Katsuragi, D.J. Durian | Avalanche statistics and time-resolved grain dynamics for a driven heap | null | Phys. Rev. E 76, 061301 (2007) | 10.1103/PhysRevE.76.061301 | null | cond-mat.soft | null | We probe the dynamics of intermittent avalanches caused by steady addition of
grains to a quasi-two dimensional heap. To characterize the time-dependent
average avalanche flow speed v(t), we image the top free surface. To
characterize the grain fluctuation speed dv(t), we use Speckle-Visibility
Spectroscopy. During an avalanche, we find that the fluctuation speed is
approximately one-tenth the average flow speed, and that these speeds are
largest near the beginning of an event. We also find that the distribution of
event durations is peaked, and that event sizes are correlated with the time
interval since the end of the previous event. At high rates of grain addition,
where successive avalanches merge into smooth continuous flow, the relationship
between average and fluctuation speeds changes to dv Sqrt[v].
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 22:17:32 GMT"
}
] | 2007-12-10T00:00:00 | [
[
"Abate",
"A. R.",
""
],
[
"Katsuragi",
"H.",
""
],
[
"Durian",
"D. J.",
""
]
] |
0708.1190 | Wayne Hu | Wayne Hu, Ignacy Sawicki (KICP, U Chicago) | A Parameterized Post-Friedmann Framework for Modified Gravity | 12 pages, 9 figures, additional references reflect PRD published
version | Phys.Rev.D76:104043,2007 | 10.1103/PhysRevD.76.104043 | null | astro-ph | null | We develop a parameterized post-Friedmann (PPF) framework which describes
three regimes of modified gravity models that accelerate the expansion without
dark energy. On large scales, the evolution of scalar metric and density
perturbations must be compatible with the expansion history defined by distance
measures. On intermediate scales in the linear regime, they form a
scalar-tensor theory with a modified Poisson equation. On small scales in dark
matter halos such as our own galaxy, modifications must be suppressed in order
to satisfy stringent local tests of general relativity. We describe these
regimes with three free functions and two parameters: the relationship between
the two metric fluctuations, the large and intermediate scale relationships to
density fluctuations and the two scales of the transitions between the regimes.
We also clarify the formal equivalence of modified gravity and generalized dark
energy. The PPF description of linear fluctuation in f(R) modified action and
the Dvali-Gabadadze-Porrati braneworld models show excellent agreement with
explicit calculations. Lacking cosmological simulations of these models, our
non-linear halo-model description remains an ansatz but one that enables
well-motivated consistency tests of general relativity. The required
suppression of modifications within dark matter halos suggests that the linear
and weakly non-linear regimes are better suited for making complementary test
of general relativity than the deeply non-linear regime.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 22:29:27 GMT"
},
{
"version": "v2",
"created": "Fri, 12 Oct 2007 03:31:48 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Hu",
"Wayne",
"",
"KICP, U Chicago"
],
[
"Sawicki",
"Ignacy",
"",
"KICP, U Chicago"
]
] |
0708.1191 | Mason A. Porter | Yan Zhang, A. J. Friend, Amanda L. Traud, Mason A. Porter, James H.
Fowler, and Peter J. Mucha | Community Structure in Congressional Cosponsorship Networks | 8 pages, 4 figures (some with multiple parts), to appear in Physica
A; additional background info and explanations added from last version | null | 10.1016/j.physa.2007.11.004 | null | nlin.AO physics.data-an physics.soc-ph | null | We study the United States Congress by constructing networks between Members
of Congress based on the legislation that they cosponsor. Using the concept of
modularity, we identify the community structure of Congressmen, as connected
via sponsorship/cosponsorship of the same legislation, to investigate the
collaborative communities of legislators in both chambers of Congress. This
analysis yields an explicit and conceptually clear measure of political
polarization, demonstrating a sharp increase in partisan polarization which
preceded and then culminated in the 104th Congress (1995-1996), when
Republicans took control of both chambers. Although polarization has since
waned in the U.S. Senate, it remains at historically high levels in the House
of Representatives.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 22:26:32 GMT"
},
{
"version": "v2",
"created": "Sun, 4 Nov 2007 23:08:56 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Zhang",
"Yan",
""
],
[
"Friend",
"A. J.",
""
],
[
"Traud",
"Amanda L.",
""
],
[
"Porter",
"Mason A.",
""
],
[
"Fowler",
"James H.",
""
],
[
"Mucha",
"Peter J.",
""
]
] |
0708.1192 | Denis Charles X. | Eric Bach and Denis Charles | The hardness of computing an eigenform | 5 Pages (corrected a typo in statement of Theorem 2.1) | null | null | null | math.NT | null | In this article, we give evidence that computing Fourier coefficients of the
Hecke eigenforms for composite indices is no easier than factoring integers. In
particular, we show that the existence of a polynomial time algorithm that,
given n, computes the n-th Fourier coefficient of a (fixed) Hecke eigenform
implies that we can factor most RSA moduli (numbers that are products of two
distinct primes) in polynomial time.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 23:35:23 GMT"
},
{
"version": "v2",
"created": "Mon, 13 Aug 2007 19:04:09 GMT"
}
] | 2007-08-13T00:00:00 | [
[
"Bach",
"Eric",
""
],
[
"Charles",
"Denis",
""
]
] |
0708.1193 | S. Ole Warnaar | S. Ole Warnaar | A Selberg integral for the Lie algebra A_n | 32 pages | Acta Mathematica 203 (2009), 269-304. | 10.1007/s11511-009-0043-x | null | math.CA math.CO math.QA | null | A new q-binomial theorem for Macdonald polynomials is employed to prove an
A_n analogue of the celebrated Selberg integral. This confirms the g=A_n case
of a conjecture by Mukhin and Varchenko concerning the existence of a Selberg
integral for every simple Lie algebra g.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 23:27:45 GMT"
}
] | 2009-12-11T00:00:00 | [
[
"Warnaar",
"S. Ole",
""
]
] |
0708.1194 | Stefan Schumacher | S. Schumacher, N. H. Kwong, and R. Binder | Influence of exciton-exciton correlations on the polarization
characteristics of the polariton amplification in semiconductor microcavities | null | null | 10.1103/PhysRevB.76.245324 | null | cond-mat.other | null | Based on a microscopic many-particle theory we investigate the influence of
excitonic correlations on the vectorial polarization state characteristics of
the parametric amplification of polaritons in semiconductor microcavities. We
study a microcavity with perfect in-plane isotropy. A linear stability analysis
of the cavity polariton dynamics shows that in the co-linear (TE-TE or TM-TM)
pump-probe polarization state configuration, excitonic correlations diminish
the parametric scattering process whereas it is enhanced by excitonic
correlations in the cross-linear (TE-TM or TM-TE) configuration. Without any
free parameters, our microscopic theory gives a quantitative understanding how
many-particle effects can lead to a rotation or change of the outgoing
(amplified) probe signal's vectorial polarization state relative to the
incoming one's.
| [
{
"version": "v1",
"created": "Wed, 8 Aug 2007 23:49:17 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Schumacher",
"S.",
""
],
[
"Kwong",
"N. H.",
""
],
[
"Binder",
"R.",
""
]
] |
0708.1195 | YaJin Zhou | Zhou Ya-Jin, Ma Wen-Gan, Han Liang and Zhang Ren-You | Associated production of graviton with $e^+e^-$ pair via photon-photon
collisions at a linear collider | Accepted by Phys. Rev. D | Phys.Rev.D76:054003,2007 | 10.1103/PhysRevD.76.054003 | null | hep-ph | null | We investigate the process \rreeG at the future International Linear
Collider(ILC), where G_n is the Kaluza-Klein graviton in the Large Extra
Dimension Model. When the fundamental energy scale is of a few ${\rm TeV}$, the
cross section of this process can reach several hundred fb at a photon-photon
collider with $\sqrt{s}=500 \sim 1000 GeV$, and the cross section in J=2
polarized photon collision mode is much larger than that in J=0 polarized
photon collision mode. We present strategies to distinguish the graviton signal
from numerous SM backgrounds, and find that the graviton signal with extra
dimensions $\delta=3$ can be detected when ${\rm M_S} \le 2.67(1.40) {\rm TeV}$
and $\gamma \gamma$ c.m.s. energy $\sqrt{s}=1000(500) {\rm GeV}$ in unpolarized
photon collision mode, while the detecting upper limit can be increased to
2.79(1.44) ${\rm TeV}$ in $+ -$ ($\lambda_1=1$, $\lambda_2=-1$) polarized
photon collision mode(with photon polarization efficiency $P_{\gamma}=0.9$).
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 00:11:27 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Ya-Jin",
"Zhou",
""
],
[
"Wen-Gan",
"Ma",
""
],
[
"Liang",
"Han",
""
],
[
"Ren-You",
"Zhang",
""
]
] |
0708.1196 | Christopher Onken | Christopher A. Onken, Monica Valluri, Bradley M. Peterson, Richard W.
Pogge, Misty C. Bentz, Laura Ferrarese, Marianne Vestergaard, D. Michael
Crenshaw, Sergey G. Sergeev, Ian M. McHardy, David Merritt, Gary A. Bower,
Timothy M. Heckman and Amri Wandel | The Black Hole Mass of NGC 4151: Comparison of Reverberation Mapping and
Stellar Dynamical Measurements | 20 pages, including 11 low-res figures. Accepted for publication in
ApJ. High resolution version available upon request | null | 10.1086/522220 | null | astro-ph | null | We present a stellar dynamical estimate of the black hole (BH) mass in the
Seyfert 1 galaxy, NGC 4151. We analyze ground-based spectroscopy as well as
imaging data from the ground and space, and we construct 3-integral
axisymmetric models in order to constrain the BH mass and mass-to-light ratio.
The dynamical models depend on the assumed inclination of the kinematic
symmetry axis of the stellar bulge. In the case where the bulge is assumed to
be viewed edge-on, the kinematical data give only an upper limit to the mass of
the BH of ~4e7 M_sun (1 sigma). If the bulge kinematic axis is assumed to have
the same inclination as the symmetry axis of the large-scale galaxy disk (i.e.,
23 degrees relative to the line of sight), a best-fit dynamical mass between
4-5e7 M_sun is obtained. However, because of the poor quality of the fit when
the bulge is assumed to be inclined (as determined by the noisiness of the
chi^2 surface and its minimum value), and because we lack spectroscopic data
that clearly resolves the BH sphere of influence, we consider our measurements
to be tentative estimates of the dynamical BH mass. With this preliminary
result, NGC 4151 is now among the small sample of galaxies in which the BH mass
has been constrained from two independent techniques, and the mass values we
find for both bulge inclinations are in reasonable agreement with the recent
estimate from reverberation mapping (4.57[+0.57/-0.47]e7 M_sun) published by
Bentz et al.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 18:10:05 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Onken",
"Christopher A.",
""
],
[
"Valluri",
"Monica",
""
],
[
"Peterson",
"Bradley M.",
""
],
[
"Pogge",
"Richard W.",
""
],
[
"Bentz",
"Misty C.",
""
],
[
"Ferrarese",
"Laura",
""
],
[
"Vestergaard",
"Marianne",
""
],
[
"Crenshaw",
"D. Michael",
""
],
[
"Sergeev",
"Sergey G.",
""
],
[
"McHardy",
"Ian M.",
""
],
[
"Merritt",
"David",
""
],
[
"Bower",
"Gary A.",
""
],
[
"Heckman",
"Timothy M.",
""
],
[
"Wandel",
"Amri",
""
]
] |
0708.1197 | Xiaojun Chen | Xiaojun Chen | An Algebraic Chain Model of String Topology | 30 pages; revised version with errors corrected | null | null | null | math.AT | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A chain complex model for the free loop space of a connected, closed and
oriented manifold is presented, and on its homology, the Gerstenhaber and
Batalin-Vilkovisky algebra structures are defined and identified with the
string topology structures. The gravity algebra on the equivariant homology of
the free loop space is also modeled. The construction includes non
simply-connected case, and therefore gives an algebraic and chain level model
of Chas-Sullivan's String Topology.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 01:24:14 GMT"
},
{
"version": "v2",
"created": "Sun, 2 Mar 2008 20:54:11 GMT"
},
{
"version": "v3",
"created": "Tue, 6 Jan 2009 02:49:35 GMT"
}
] | 2009-01-06T00:00:00 | [
[
"Chen",
"Xiaojun",
""
]
] |
0708.1198 | Feng Ye | F. Ye, J. A. Fernandez-Baca, R. S. Fishman, Y. Ren, H. J. Kang, Y.
Qiu, and T. Kimura | Magnetic Interaction in the Geometrically Frustrated Triangular Lattice
Antiferromagnet $\rm CuFeO_2$ | 4 pages, 4 figures, published in Phys. Rev. Lett | Phys. Rev. Lett. 99, 157201 (2007) | 10.1103/PhysRevLett.99.157201 | null | cond-mat.str-el cond-mat.mtrl-sci | null | The spin wave excitations of the geometrically frustrated triangular lattice
antiferromagnet (TLA) $\rm CuFeO_2$ have been measured using high resolution
inelastic neutron scattering. Antiferromagnetic interactions up to third
nearest neighbors in the ab plane (J_1, J_2, J_3, with $J_2/J_1 \approx 0.44$
and $J_3/J_1 \approx 0.57$), as well as out-of-plane coupling (J_z, with
$J_z/J_1 \approx 0.29$) are required to describe the spin wave dispersion
relations, indicating a three dimensional character of the magnetic
interactions. Two energy dips in the spin wave dispersion occur at the
incommensurate wavevectors associated with multiferroic phase, and can be
interpreted as dynamic precursors to the magnetoelectric behavior in this
system.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 01:48:39 GMT"
},
{
"version": "v2",
"created": "Mon, 8 Oct 2007 20:10:53 GMT"
}
] | 2007-10-08T00:00:00 | [
[
"Ye",
"F.",
""
],
[
"Fernandez-Baca",
"J. A.",
""
],
[
"Fishman",
"R. S.",
""
],
[
"Ren",
"Y.",
""
],
[
"Kang",
"H. J.",
""
],
[
"Qiu",
"Y.",
""
],
[
"Kimura",
"T.",
""
]
] |
0708.1199 | Edward W. Kolb | Rocky Kolb (Department of Astronomy & Astrophysics, The Enrico Fermi
Institute, and The Kavli Institute for Cosmological Physics, The University
of Chicago) | A Thousand Invisible Cords Binding Astronomy and High-Energy Physics | Why "Fundamentalist" Physics Is Good for Astronomy (in response to
the paper of Simon White, arXiv:0704.2291) | Rept.Prog.Phys.70:1583-1596,2007 | 10.1088/0034-4885/70/10/R01 | null | astro-ph hep-ex hep-ph | null | The traditional realm of astronomy is the observation and study of the
largest objects in the Universe, while the traditional domain of high-energy
physics is the study of the smallest things in nature. But these two sciences
concerned with opposite ends of the size spectrum are, in Muir's words, bound
fast by a thousand invisible cords that cannot be broken. In this essay I
propose that collaborations of astronomers and high-energy physicists on common
problems are beneficial for both fields, and that both astronomy and
high-energy physics can advance by this close and still growing relationship.
Dark matter and dark energy are two of the binding cords I will use to
illustrate how collaborations of astronomers and high-energy physicists on
large astronomical projects can be good for astronomy, and how discoveries in
astronomy can guide high-energy physicists in their quest for understanding
nature on the smallest scales. Of course, the fields have some different
intellectual and collaborative traditions, neither of which is ideal. The
cultures of the different fields cannot be judged to be right or wrong; they
either work or they don't. When astronomers and high-energy physicists work
together, the binding cords can either encourage or choke creativity. The
challenge facing the astronomy and high-energy physics communities is to adopt
the best traditions of both fields. It is up to us to choose wisely.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 18:34:02 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Kolb",
"Rocky",
"",
"Department of Astronomy & Astrophysics, The Enrico Fermi\n Institute, and The Kavli Institute for Cosmological Physics, The University\n of Chicago"
]
] |
0708.1200 | Zhenyue Zhu | Zhenyue Zhu, Yong Wang, Ke Xia, X. C. Xie, Zhongshui Ma | Time reversal Aharonov-Casher effect in mesoscopic rings with Rashba
spin-orbital interaction | 5 pages, 4 figures, accepted by Phys. Rev. B | Phys. Rev. B 76, 125311 (2007) | 10.1103/PhysRevB.76.125311 | null | cond-mat.mes-hall | null | The time reversal Aharonov-Casher (AC) interference effect in the mesoscopic
ring structures, based on the experiment in Phys. Rev. Lett. \textbf{97},
196803 (2006), is studied theoretically. The transmission curves are calculated
from the scattering matrix formalism, and the time reversal AC interference
frequency is singled out from the Fourier spectra in numerical simulations.
This frequency is in good agreement with analytical result. It is also shown
that in the absent of magnetic field, the Altshuler-Aronov-Spivak type (time
reversal) AC interference retains under the influence of strong disorder, while
the Aharonov-Bohm type AC interference is suppressed.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 03:02:48 GMT"
}
] | 2011-11-10T00:00:00 | [
[
"Zhu",
"Zhenyue",
""
],
[
"Wang",
"Yong",
""
],
[
"Xia",
"Ke",
""
],
[
"Xie",
"X. C.",
""
],
[
"Ma",
"Zhongshui",
""
]
] |
0708.1201 | Takeshi Itoh | Takeshi Itoh, Chris Done, Kazuo Makishima, Grzegorz Madejski,
Hisamitsu Awaki, Naoki Isobe, Poshak Gandhi, Gulab C. Dewangan, Richard E.
Griffiths, Naohisa Anabuki, Takashi Okajima, James Reeves, Tadayuki
Takahashi, Yoshihiro Ueda, Satohi Eguchi, Tahir Yaqoob | Suzaku wide-band X-ray Spectroscopy of the Seyfert 2 AGN in NGC 4945 | 11 pages, 11 figures | null | 10.1093/pasj/60.sp1.S251 | null | astro-ph | null | Suzaku observed a nearby Seyfert 2 galaxy NGC4945, which hosts one of the
brightest active galactic nuclei above 20 keV. Combining data from the X-ray
CCD camera (XIS) and the Hard X-ray Detector (HXD), the AGN intrinsic nuclear
emission and its reprocessed signals were observed simultaneously. The
intrinsic emission is highly obscured with an absorbing column of $\sim 5
\times 10^{24}$ cm$^{-2}$, and was detectable only above $\sim 10$ keV. The
spectrum below 10 keV is dominated by reflection continuum and emission lines
from neutral/ionized material. Along with a neutral iron K$\alpha$ line, a
neutral iron K$\beta$ and a neutral nickel K$\alpha$ line were detected for the
first time from this source. The neutral lines and the cold reflection
continuum are consistent with both originating in the same location. The
Compton down-scattered shoulder in the neutral Fe-K$\alpha$ line is $\sim 10%$
in flux of the narrow core, which confirms that the line originates from
reflection rather than transmission. The weakness of the Compton shoulder also
indicates that the reflector is probably seen nearly edge-on. Flux of the
intrinsic emission varied by a factor of $\sim 2$ within $\sim 20$ ks, which
requires the obscuring material to be geometrically thin. Broadband spectral
modeling showed that the solid angle of the neutral reflector is less than a
few $\times 10^{-2} \times 2\pi$. All this evidence regarding the reprocessed
signals suggests that a disk-like absorber/reflector is viewed from a near
edge-on angle.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 02:43:59 GMT"
}
] | 2017-01-18T00:00:00 | [
[
"Itoh",
"Takeshi",
""
],
[
"Done",
"Chris",
""
],
[
"Makishima",
"Kazuo",
""
],
[
"Madejski",
"Grzegorz",
""
],
[
"Awaki",
"Hisamitsu",
""
],
[
"Isobe",
"Naoki",
""
],
[
"Gandhi",
"Poshak",
""
],
[
"Dewangan",
"Gulab C.",
""
],
[
"Griffiths",
"Richard E.",
""
],
[
"Anabuki",
"Naohisa",
""
],
[
"Okajima",
"Takashi",
""
],
[
"Reeves",
"James",
""
],
[
"Takahashi",
"Tadayuki",
""
],
[
"Ueda",
"Yoshihiro",
""
],
[
"Eguchi",
"Satohi",
""
],
[
"Yaqoob",
"Tahir",
""
]
] |
0708.1202 | Velimir Jurdjevic | Velimir Jurdjevic | The symplectic structure of curves in three dimensional spaces of
constant curvature and the equations of mathematical physics | null | null | null | null | math.SG math.AP | null | This paper defines a symplectic form on the infinite dimensional Fr\'echet
manifold of framed curves of fixed length over a simply connected Riemannian
manifold of constant curvature. The paper then considers Hamiltonian systems
generated by the geometric invariants of the curves on the base manifold and
relates them to the equations of mathematical physics.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 03:35:38 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Jurdjevic",
"Velimir",
""
]
] |
0708.1203 | Kikuo Harigaya | Kikuo Harigaya | Exciton Effects in Optical Absorption of Boron-Nitride Nanotubes | 4 pages, 3 figure | Jpn. J. Appl. Phys. 48 (2009) 065007 | 10.1143/JJAP.48.065007 | null | cond-mat.mtrl-sci cond-mat.str-el physics.chem-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | Exciton effects are studied in single-wall boron-nitride (BN) nanotubes.
Linear absorption spectra are calculated with changing the chiral index of the
zigzag nanotubes. We consider the extended Hubbard model with atomic energies
at the boron and nitrogen sites. Exciton effects are calculated using the
configuration interaction technique. The Coulomb interaction dependence of the
band gap, the lowest exciton energy, and the binding energy of the exciton are
discussed. The optical gap of the (5,0) nanotube is about 6 eV at the onsite
interaction U=2t with the hopping integral t=1.2 eV. The binding energy of the
exciton is 0.50 eV for these parameters. This energy agrees well with that of
other theoretical investigations. We find that the energy gap and the binding
energy are almost independent of the geometries of the nanotubes. This novel
property is in contrast with that of the carbon nanotubes which show metallic
and semiconducting properties depending on the chiral index.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 02:36:33 GMT"
},
{
"version": "v2",
"created": "Tue, 19 May 2009 01:45:53 GMT"
}
] | 2009-07-07T00:00:00 | [
[
"Harigaya",
"Kikuo",
""
]
] |
0708.1204 | Zhongmu Li | Zhongmu Li, Zhanwen Han | An Isochrone Database and a Rapid Model for Stellar Population Synthesis | 11 pages, 18 figures, Accepted by MNRAS | null | 10.1111/j.1365-2966.2008.12793.x | null | astro-ph | null | We first presented an isochrone database that can be widely used for stellar
population synthesis studies and colour-magnitude diagram (CMD) fitting. The
database consists of the isochrones of both single star and binary star simple
stellar populations (ss-SSPs and bs-SSPs). The ranges for the age and
metallicity of populations are 0--15 Gyr and 0.0001--0.03, respectively. All
data are available for populations with Salpeter IMF and Chabrier IMF. Then
based on the isochrone database, we built a rapid stellar population synthesis
(RPS) model and calculated the high-resolution (0.3 AA) integrated spectral
energy distributions (SEDs), Lick indices and colour indices for bs-SSPs and
ss-SSPs. In particular, we calculated the UBVRIJHKLM colours, ugriz colours and
some composite colours that consist of magnitudes on different systems. As an
example for applying the isochrone database for CMD fitting, we fitted the CMDs
of star clusters M67 and NGC1868 and obtained their distance moduli, colour
excesses, stellar metallicities and ages. The results showed that the
isochrones of bs-SSPs are closer to those of real star clusters. The isochrone
database, colours, Lick indices of populations can be downloaded via
http://www.ynao.ac.cn/~bps/zhongmu/download.htm
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 03:07:50 GMT"
},
{
"version": "v2",
"created": "Sat, 11 Aug 2007 03:15:19 GMT"
},
{
"version": "v3",
"created": "Mon, 20 Aug 2007 08:49:11 GMT"
},
{
"version": "v4",
"created": "Thu, 15 Nov 2007 08:30:01 GMT"
},
{
"version": "v5",
"created": "Sun, 2 Dec 2007 08:03:40 GMT"
},
{
"version": "v6",
"created": "Tue, 11 Mar 2008 07:48:32 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Li",
"Zhongmu",
""
],
[
"Han",
"Zhanwen",
""
]
] |
0708.1205 | Eric Herbold | E.B. Herbold, J. Cai, D.J. Benson and V.F. Nesterenko | Simulation of Particle Size Effect on Dynamic Properties and Fracture of
PTFE-W-Al Composites | 5 pages, 6 figures | null | 10.1063/1.2833241 | null | cond-mat.soft cond-mat.mtrl-sci | null | Recent investigations of the dynamic compressive strength of cold
isostatically pressed composites of polytetrafluoroethylene (PTFE), tungsten
(W) and aluminum (Al) powders show significant differences depending on the
size of metallic particles. The addition of W increases the density and overall
strength of the sample. To investigate relatively large deformations
multi-material Eulerian and arbitrary Lagrangian-Eulerian methods, which have
the ability to efficiently handle the formation of free surfaces, were used.
The calculations indicate that the increased strength of the sample with fine
metallic particles is due to the formation of force chains under dynamic
loading. This phenomenon occurs even at larger porosity of the PTFE matrix in
comparison with samples with larger particle size of W and higher density of
the PTFE matrix.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 02:59:26 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Herbold",
"E. B.",
""
],
[
"Cai",
"J.",
""
],
[
"Benson",
"D. J.",
""
],
[
"Nesterenko",
"V. F.",
""
]
] |
0708.1206 | Xiaojun Bi | Xiao-Jun Bi | Constraining supersymmetry from the satellite experiments | 19 pages, 5 gigures; references added, more discussions added | Phys.Rev.D76:123511,2007 | 10.1103/PhysRevD.76.123511 | null | astro-ph hep-ph | null | In this paper we study the detectability of $\gamma$-rays from dark matter
annihilation in the subhalos of the Milky Way by the satellite-based
experiments, EGRET and GLAST. We work in the frame of supersymmetric extension
of the standard model and assume the lightest neutralino being the dark matter
particles. Based on the N-body simulation of the evolution of dark matter
subhalos we first calculate the average intensity distribution of this new
class of $\gamma$-ray sources by neutralino annihilation. It is possible to
detect these $\gamma$-ray sources by EGRET and GLAST. Conversely, if these
sources are not detected the nature of the dark matter particls will be
constrained by these experiments, which, however, depending on the
uncertainties of the subhalo profile.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 03:10:37 GMT"
},
{
"version": "v2",
"created": "Tue, 16 Oct 2007 12:23:41 GMT"
},
{
"version": "v3",
"created": "Mon, 10 Dec 2007 07:42:12 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Bi",
"Xiao-Jun",
""
]
] |
0708.1207 | Hosho Katsura | Hosho Katsura, Yasuyuki Hatsuda | Entanglement Entropy in the Calogero-Sutherland Model | 14 pages, 3figures, references added | J.Phys.A40:13931,2007 | 10.1088/1751-8113/40/46/007 | null | cond-mat.stat-mech cond-mat.mes-hall cond-mat.str-el hep-th quant-ph | null | We investigate the entanglement entropy between two subsets of particles in
the ground state of the Calogero-Sutherland model. By using the duality
relations of the Jack symmetric polynomials, we obtain exact expressions for
both the reduced density matrix and the entanglement entropy in the limit of an
infinite number of particles traced out. From these results, we obtain an upper
bound value of the entanglement entropy. This upper bound has a clear
interpretation in terms of fractional exclusion statistics.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 03:28:31 GMT"
},
{
"version": "v2",
"created": "Thu, 23 Aug 2007 13:01:13 GMT"
}
] | 2016-09-08T00:00:00 | [
[
"Katsura",
"Hosho",
""
],
[
"Hatsuda",
"Yasuyuki",
""
]
] |
0708.1208 | Werner Stulpe | Werner Stulpe | Topologies and Measurable Structures on the Projective Hilbert Space | 11 pages | null | null | null | math-ph math.MP | null | A systematic review of the various topologies that can be defined on the
projective Hilbert space P(H), i.e., on the set of the pure quantum states, is
presented. It is shown that P(H) carries a natural topology as well as a
natural measurable structure.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 03:30:14 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Stulpe",
"Werner",
""
]
] |
0708.1209 | Erasmo Recami | Michel Zamboni-Rached, Erasmo Recami and Hugo E. Hernandez-Figueroa | Structure of the Nondiffracting (Localized) Waves, and some interesting
applications | Article (mainly a review) with 37 pages and 8 Figures. An improved
version of this paper will appear as Chpater 2 of the book "Localized Waves"
(J.Wiley; in press), ed. by H.E.Hernandez-Figueroa, M.Zamboni-Rached, and
E.Recami | Chapt 2 in "Localized Waves" (book ISBN 978-0-470-10885-7, ed. by
H.E.H.Figueroa, M.Z.Rached and E.Recami), J.Wiley, 2008; pp.43-77. | null | null | physics.gen-ph physics.class-ph physics.optics | null | Since the early works[1-4] on the so-called nondiffracting waves (called also
Localized Waves), a great deal of results has been published on this important
subject, from both the theoretical and the experimental point of view.
Initially, the theory was developed taking into account only free space;
however, in recent years, it has been extended for more complex media
exhibiting effects such as dispersion[5-7], nonlinearity[8], anisotropy[9] and
losses[10]. Such extensions have been carried out along with the development of
efficient methods for obtaining nondiffracting beams and pulses in the
subluminal, luminal and superluminal regimes[11-18]. This paper (partly a
review) addresses some theoretical methods related to nondiffracting solutions
of the linear wave equation in unbounded homogeneous media, as well as to some
interesting applications of such waves. In section II we analyze the general
structure of the Localized Waves, develop the so called Generalized
Bidirectional Decomposition, and use it to obtain several luminal and
superluminal (especially X-shaped) nondiffracting solutions of the wave
equation. In section III we develop a space-time focusing method by a
continuous superposition of X-Shaped pulses of different velocities. Section IV
addresses the properties of chirped optical X-Shaped pulses propagating in
material media without boundaries. Finally, in Section V, we show how a
suitable superposition of Bessel beams can be used to obtain stationary
localized wave fields, with a static envelope and a high transverse
localization, and whose longitudinal intensity pattern can assume any desired
shape within a chosen interval of the propagation axis.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 03:40:10 GMT"
}
] | 2010-01-31T00:00:00 | [
[
"Zamboni-Rached",
"Michel",
""
],
[
"Recami",
"Erasmo",
""
],
[
"Hernandez-Figueroa",
"Hugo E.",
""
]
] |
0708.1210 | Peter B. Gilkey | M. Brozos-Vazquez, P. Gilkey, S. Nikcevic, and U. Simon | Projectively Osserman manifolds | null | null | null | null | math.DG | null | One says that a smooth manifold M is a pseudo-Riemannian manifold of
signature (p,q) if the tangent bundle TM is equipped with a smooth
non-degenerate symmetric inner product g of signature (p,q). Similarly one says
that M is an affine manifold if TM is equipped with a torsion free connection.
One says g is Osserman if the eigenvalues of the Jacobi operator are constant
on the pseudo-sphere bundles of unit timelike and spacelike vectors. We extend
this concept from the pseudo-Riemannian to the affine setting to define the
notion of a projectively Osserman manifold. This notion is the focus of the
paper. We establish some basic results concerning projectively Osserman
manifolds and exhibit examples of this structure which arise in several
different geometrical contexts.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 13:09:23 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Brozos-Vazquez",
"M.",
""
],
[
"Gilkey",
"P.",
""
],
[
"Nikcevic",
"S.",
""
],
[
"Simon",
"U.",
""
]
] |
0708.1211 | Mark Iwen | M. A. Iwen | A Deterministic Sub-linear Time Sparse Fourier Algorithm via
Non-adaptive Compressed Sensing Methods | 16 pages total, 10 in paper, 6 in appended | null | null | null | cs.DM cs.NA | null | We study the problem of estimating the best B term Fourier representation for
a given frequency-sparse signal (i.e., vector) $\textbf{A}$ of length $N \gg
B$. More explicitly, we investigate how to deterministically identify B of the
largest magnitude frequencies of $\hat{\textbf{A}}$, and estimate their
coefficients, in polynomial$(B,\log N)$ time. Randomized sub-linear time
algorithms which have a small (controllable) probability of failure for each
processed signal exist for solving this problem. However, for failure
intolerant applications such as those involving mission-critical hardware
designed to process many signals over a long lifetime, deterministic algorithms
with no probability of failure are highly desirable. In this paper we build on
the deterministic Compressed Sensing results of Cormode and Muthukrishnan (CM)
\cite{CMDetCS3,CMDetCS1,CMDetCS2} in order to develop the first known
deterministic sub-linear time sparse Fourier Transform algorithm suitable for
failure intolerant applications. Furthermore, in the process of developing our
new Fourier algorithm, we present a simplified deterministic Compressed Sensing
algorithm which improves on CM's algebraic compressibility results while
simultaneously maintaining their results concerning exponential decay.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 04:07:06 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Iwen",
"M. A.",
""
]
] |
0708.1212 | Utkir Rozikov A | N.N. Ganikhodjaev, U.A. Rozikov | On a Phase Separation Point for One - Dimensional Models | 10 pages | null | null | null | math-ph math.MP | null | In the paper a one-dimensional model with nearest - neighbor interactions
$I_n, n\in \Z$ and spin values $\pm 1$ is considered. It is known that under
some conditions on parameters $I_n$ the phase transition occurs for the model.
We define a notion of "phase separation" point between two phases. We prove
that the expectation value of the point is zero and its the mean square
fluctuation is bounded by a constant $C(\beta)$ which tends to 1/4 if
$\beta\to\infty$. Here $\beta=\frac{1}{T}$, $ T>0$-temperature.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 04:18:58 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Ganikhodjaev",
"N. N.",
""
],
[
"Rozikov",
"U. A.",
""
]
] |
0708.1213 | Kaner Kaner | Er-Jun Kan, Zhenyu Li, Jinlong Yang, J. G. Hou | Will Zigzag Graphene Nanoribbon Turn to Half Metal under Electric Field? | 8 pages, 3 figures | Appl. Phys. Lett 91, 243116 (2007) | 10.1063/1.2821112 | null | cond-mat.mtrl-sci | null | At B3LYP level of theory, we predict that the half-metallicity in zigzag edge
graphene nanoribbon (ZGNR) can be realized when an external electric field is
applied across the ribbon. The critical electric field to induce the
half-metallicity decreases with the increase of the ribbon width. Both the spin
polarization and half-metallicity are removed when the edge state electrons
fully transferred from one side to the other under very strong electric field.
The electric field range under which ZGNR remain half-metallic increases with
the ribbon width. Our study demonstrates a rich field-induced spin polarization
behavior, which may leads to some important applications in spinstronics.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 05:11:59 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Kan",
"Er-Jun",
""
],
[
"Li",
"Zhenyu",
""
],
[
"Yang",
"Jinlong",
""
],
[
"Hou",
"J. G.",
""
]
] |
0708.1214 | Rong-Gen Cai | Yi Zhang, Hui Li, Xing Wu, Hao Wei, Rong-Gen Cai | Age constraints on the Agegraphic Dark Energy Model | Revtex, 11 pages with 6 figures | null | null | null | astro-ph gr-qc hep-th | null | We investigate the age constraint on the agegraphic dark energy model by
using two old galaxies (LBDS 53W091 and LBDS 53W069) and the old high redshift
quasar APM 08279+5255. We find that the agegraphic dark energy model can easily
accommodate LBDS 53W091 and LBDS 53W069. To accommodate APM 08279+5255, one can
take the reduced Hubble parameter as large as h=0.64, when the fraction matter
energy density $\Omega_{m0}\approx 0.22$.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 12:42:11 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Zhang",
"Yi",
""
],
[
"Li",
"Hui",
""
],
[
"Wu",
"Xing",
""
],
[
"Wei",
"Hao",
""
],
[
"Cai",
"Rong-Gen",
""
]
] |
0708.1215 | Cheongho Han | Cheongho Han (Chungbuk Natl. Univ., Korea) | Near-Field Microlensing from Wide-Field Surveys | 6 pages, 2 tables, 3 figures (one in jpg format) | null | 10.1086/588083 | null | astro-ph | null | We estimate the rate of near-field microlensing events expected from all-sky
surveys and investigate the properties of these events. Under the assumption
that all lenses are composed of stars, our estimation of the event rate ranges
from \Gamma_{tot}~0.2 yr^{-1}$ for a survey with a magnitude limit of
V_{lim}=12 to \Gamma_{tot}~20 yr^{-1} for a survey with V_{lim}=18. We find
that the average distances to source stars and lenses vary considerably
depending on the magnitude limit, while the dependencies of the average event
time scale and lens-source transverse speed are weak and nearly negligible,
respectively. We also find that the the average lens-source proper motion of
events expected even from a survey with V_{lim}=18 would be <\mu> >~ 40 mas
yr^{-1}, implying that the source and lens of a significant fraction of
near-field events could be resolved from high-resolution follow-up
observations. From the investigation of the variation of the event
characteristics depending on the position of the sky, we find that the average
distances to source stars and lenses become shorter, the lens-source transverse
speed increases, and the time scale becomes shorter as the the galactic
latitude of the field increases. Due to the concentration of events near the
galactic plane, we find that >~ 50 % of events would be detected in the field
with b <= 20^\circ.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 05:24:48 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Han",
"Cheongho",
"",
"Chungbuk Natl. Univ., Korea"
]
] |
0708.1216 | Nimisha Kantharia | N. G. Kantharia (1), G. C. Anupama (2), T. P. Prabhu (2), S. Ramya
(2), M. F. Bode (3), S. P. S. Eyres (4), T. J. O'Brien (5) ((1) National
Centre for Radio Astrophysics (TIFR), Pune (2) Indian Institute of
Astrophysics, Bangalore (3) Liverpool John Moores University (4) University
of Central Lancashire (5) Jodrell Bank Observatory, University of Manchester) | GMRT Observations of the 2006 outburst of the Nova RS Ophiuchi: First
detection of emission at radio frequencies < 1.4 GHz | 14 pages, 1 figure. Accepted for publication in ApJL | null | 10.1086/522201 | null | astro-ph | null | The first low radio frequency (<1.4 GHz) detection of the outburst of the
recurrent nova RS Ophiuchi is presented in this letter. Radio emission was
detected at 0.61 GHz on day 20 with a flux density of ~48 mJy and at 0.325 GHz
on day 38 with a flux density of ~ 44 mJy. This is in contrast with the 1985
outburst when it was not detected at 0.327 GHz even on day 66. The emission at
low radio frequencies is clearly non-thermal and is well-explained by a
synchrotron spectrum of index alpha ~ -0.8 (S propto nu^alpha) suffering
foreground absorption due to the pre-existing, ionized, warm, clumpy red giant
wind. The absence of low frequency radio emission in 1985 and the earlier
turn-on of the radio flux in the current outburst are interpreted as being due
to higher foreground absorption in 1985 compared to that in 2006, suggesting
that the overlying wind densities in 2006 are only ~30% of those in 1985.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 05:54:03 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Kantharia",
"N. G.",
""
],
[
"Anupama",
"G. C.",
""
],
[
"Prabhu",
"T. P.",
""
],
[
"Ramya",
"S.",
""
],
[
"Bode",
"M. F.",
""
],
[
"Eyres",
"S. P. S.",
""
],
[
"O'Brien",
"T. J.",
""
]
] |
0708.1217 | Chungku Kim | Chungku Kim | Derivation of the Recursion Relation for the Feynman Diagrams of the CJT
effective action | 7 pages, 2 figures | J.Korean Phys.Soc.51:1873,2007 | 10.3938/jkps.51.1873 | null | hep-th | null | We derive a new recursion relation to obtain the Feynman diagrams of the
Cornwall-Jackiw-Toumboulis(CJT) effective action by using the functional
derivative identities. By using this recursion relation we show the
two-particle-irreducibility of the Feynman diagrams of the CJT effective action
by induction. We apply the recursion relation to obtain the Feynman diagrams of
the CJT effective action up to the four-loop order in case of the bosonic field
theory.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 06:35:46 GMT"
}
] | 2011-08-04T00:00:00 | [
[
"Kim",
"Chungku",
""
]
] |
0708.1218 | Valentina Klochkova | V.G. Klochkova, V.E. Panchuk, E.L. Chentsov, M.V. Yushkin | The evolutionary status of the semiregular variable QYSge | 29 pages, 8 figures, 4 tables; accepted by Astrophys. Bulletin | null | 10.1134/S1990341307030030 | null | astro-ph | null | Repeated spectroscopic observations made with the 6m telescope of yielded new
data on the radial-velocity variability of the anomalous yellow supergiant
QYSge. The strongest and most peculiar feature in its spectrum is the complex
profile of NaI D lines, which contains a narrow and a very wide emission
components. The wide emission component can be seen to extend from -170 to +120
km/s, and at its central part it is cut by an absorption feature, which, in
turn, is split into two subcomponents by a narrow (16km/s at r=2.5) emission
peak. An analysis of all the Vr values leads us to adopt for the star a
systemic velocity of Vr=-21.1 km/s, which corresponds to the position of the
narrow emission component of NaI. The locations of emission-line features of
NaI D lines are invariable, which point to their formation in regions that are
external to the supergiant's photosphere. Differential line shifts of about
10km/s are revealed. The absorption lines in the spectrum of QYSge have a
substantial width of FWHM~45 km/s. The method of model atmospheres is used to
determine the following parameters: Teff=6250K, lg g=2.0, and microturbulence
Vt=4.5km/s. The metallicity of the star is found to be somewhat higher than the
solar one with an average overabundance of iron-peak elements of [Met/H]=+0.20.
The star is found to be slightly overabundant in carbon and nitrogen,
[C/Fe]=+0.25, [N/Fe]=+0.27. The alpha-process elements Mg, Si, and Ca are
slightly overabundant [alpha/H]=+0.12. The strong sodium excess, [Na/Fe]=+0.75,
is likely to be due to the dredge-up of the matter processed in the NeNa cycle.
Heavy elements of the s-process are underabundant relative to the Sun. On the
whole, the observed properties of QYSge do not give grounds for including this
star into the group of RCrB or RVTau-type type objects.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 07:21:05 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Klochkova",
"V. G.",
""
],
[
"Panchuk",
"V. E.",
""
],
[
"Chentsov",
"E. L.",
""
],
[
"Yushkin",
"M. V.",
""
]
] |
0708.1219 | Mark Kuzyk | Mark C. Kuzyk and Mark G. Kuzyk | Monte Carlo Studies of the Fundamental Limits of the Intrinsic
Hyperpolarizability | 7 pages, 5 figures | null | 10.1364/JOSAB.25.000103 | null | physics.optics physics.atom-ph | null | The off-resonant hyperpolarizability is calculated using the dipole-free
sum-over-stats expression from a randomly chosen set of energies and transition
dipole moments that are forced to be consistent with the sum rules. The process
is repeated so that the distribution of hyperpolarizabilities can be
determined. We find this distribution to be a cycloid-like function. In
contrast to variational techniques that when applied to the potential energy
function yield an intrinsic hyperpolarizability less than 0.71, our Monte Carlo
method yields values that approach unity. While many transition dipole moments
are large when the calculated hyperpolarizability is near the fundamental
limit, only two excited states dominate the hyperpolarizability - consistent
with the three-level ansatz.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 06:53:51 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Kuzyk",
"Mark C.",
""
],
[
"Kuzyk",
"Mark G.",
""
]
] |
0708.1220 | Kourosh Nozari | Kourosh Nozari and Behnaz Fazlpour | UV/IR Mixing and Black Hole Thermodynamics | 17 pages, 3 eps figures, accepted for publication in IJMPD | Int.J.Mod.Phys.D17:55-69,2008 | 10.1142/S0218271808011869 | null | gr-qc | null | The goal of this paper is to investigate the final stage of black hole
evaporation process in the framework of Lorentz violating Modified Dispersion
Relations(MDRs). As a consequence of MDRs, the high energy sector of the
underlying field theory does not decouple from the low energy sector, the
phenomenon which is known as UV/IR mixing. In the absence of exact
supersymmetry, we derive a modified dispersion relation which shows UV/IR
mixing by a novel energy dependence. Then we investigate the effects of these
type of MDRs on the thermodynamics of a radiating noncommutative Schwarzschild
black hole. The final stage of black hole evaporation obtained in this
framework is compared with existing pictures.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 07:13:49 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Nozari",
"Kourosh",
""
],
[
"Fazlpour",
"Behnaz",
""
]
] |
0708.1221 | Gregory Crosswhite | Gregory M. Crosswhite and Dave Bacon | Finite automata for caching in matrix product algorithms | 18 pages, 19 figures, LaTeX; numerous improvements have been made to
the manuscript in response to referee feedback | Phys. Rev. A 78, 012356 (2008) | 10.1103/PhysRevA.78.012356 | null | quant-ph | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | A diagram is introduced for visualizing matrix product states which makes
transparent a connection between matrix product factorizations of states and
operators, and complex weighted finite state automata. It is then shown how one
can proceed in the opposite direction: writing an automaton that ``generates''
an operator gives one an immediate matrix product factorization of it. Matrix
product factorizations have the advantage of reducing the cost of computing
expectation values by facilitating caching of intermediate calculations. Thus
our connection to complex weighted finite state automata yields insight into
what allows for efficient caching in matrix product algorithms. Finally, these
techniques are generalized to the case of multiple dimensions.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 07:42:18 GMT"
},
{
"version": "v2",
"created": "Mon, 22 Oct 2007 19:07:15 GMT"
},
{
"version": "v3",
"created": "Mon, 7 Jul 2008 17:04:05 GMT"
}
] | 2008-08-18T00:00:00 | [
[
"Crosswhite",
"Gregory M.",
""
],
[
"Bacon",
"Dave",
""
]
] |
0708.1222 | Roman G. Mints | M. Moshe and R. G. Mints | Shapiro steps in Josephson junctions with alternating critical current
density | 5 pages, 3 figures, accepted for publication in Phys. Rev. B | Phys. Rev. B 76, 054518 (2007) | 10.1103/PhysRevB.76.054518 | null | cond-mat.supr-con | null | We treat theoretically Shapiro steps in tunnel Josephson junctions with
spatially alternating critical current density. Explicit analytical formulas
for the width of the first integer (normal) and half-integer (anomalous)
Shapiro steps are derived for short junctions. We develop coarse-graining
approach, which describes Shapiro steps in the voltage-current curves of the
asymmetric grain boundaries in YBCO thin films and different
superconductor-ferromagnet-superconductor Josephson-type heterostructures.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 07:48:05 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Moshe",
"M.",
""
],
[
"Mints",
"R. G.",
""
]
] |
0708.1223 | Alexander Balandin | I. Calizo, A.A. Balandin, F. Miao, W. Bao and C.N. Lau | Temperature Coefficients of the Raman Peaks for the Single-Layer and
Bi-Layer Graphene | null | Nano Letters, Vol. 7, No. 9, 2645 - 2649 (2007) | null | null | cond-mat.mtrl-sci cond-mat.mes-hall | null | We carried out micro-Raman spectroscopy of graphene layers over the
temperature range from approximately 80 K to 370 K. The number of layers was
independently confirmed by the quantum Hall measurements and atomic force
microscopy. The measured values of the temperature coefficients for the G and
2D-band frequencies of the single-layer graphene are -0.016 1/(cm K) and -0.034
1/(cm K), respectively. The G peak temperature coefficient of the bi-layer
graphene and bulk graphite are -0.015 1/(cm K) and -0.011 1/(cm K),
respectively.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 08:04:10 GMT"
}
] | 2008-03-15T00:00:00 | [
[
"Calizo",
"I.",
""
],
[
"Balandin",
"A. A.",
""
],
[
"Miao",
"F.",
""
],
[
"Bao",
"W.",
""
],
[
"Lau",
"C. N.",
""
]
] |
0708.1224 | Ross McPhedran Prof | I.J. Zucker and R.C. McPhedran | Dirichlet L-series with real and complex characters and their
application to solving double sums | 21 pages, 1 table | null | 10.1098/rspa.2007.0162 | null | math-ph math.MP | null | A description of the properties of \L with complex characters is given. By
using these, together with the more familiar \L with real characters, it is
shown how certain two dimensional lattice sums, which previously could not be
put into closed form, may now be expressed in this way.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 08:17:52 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Zucker",
"I. J.",
""
],
[
"McPhedran",
"R. C.",
""
]
] |
0708.1225 | Yue Chongxing | Chong-Xing Yue, Li-Hong Wang, Jia Wen | Single production of heavy top quark from the three-site Higgsless model | latex files, 13 pages, 5 figures | Chin.Phys.Lett.25:1613-1616,2008 | 10.1088/0256-307X/25/5/025 | null | hep-ph | null | We consider single production of the heavy top quark T predicted by the
three-site Higgsless model in future high energy collider experiments, such as
the high energy linear e^{+}e^{-} collider (ILC), the linear-ring type $ep$
collider (THERA), and the CERN Large Hadron Collider (LHC). Our numerical
results show that the possible signals of the heavy top quark T might be
observed via the process $e^{+}e^{-}\to t\bar{T}\to t\bar{t}Z$ in future ILC
experiments and via the subprocess $qb\to q'T$ at the LHC.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 08:18:54 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Yue",
"Chong-Xing",
""
],
[
"Wang",
"Li-Hong",
""
],
[
"Wen",
"Jia",
""
]
] |
0708.1226 | Xian Gao | Xian Gao | Non-supersymmetric Attractors in Born-Infeld Black Holes with a
Cosmological Constant | 18 pages, no figue | JHEP 0711:006,2007 | 10.1088/1126-6708/2007/11/006 | null | hep-th | null | We investigate the attractor mechanism for spherically symmetric extremal
black holes in Einstein-Born-Infeld-dilaton theory of gravity in
four-dimensions, in the presence of a cosmological constant. We look for
solutions analytic near the horizon by using perturbation method. It is shown
that the values of the scalar fields at the horizon are only dependent on the
charges carried by the black hole and are irrelevant in their asymptotic
values. This analysis supports the validity of non-supersymmetric attractors in
the presence of higher derivative interactions in the gauge fields part and in
non-asymptotically flat spacetime.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 09:01:29 GMT"
},
{
"version": "v2",
"created": "Fri, 10 Aug 2007 09:52:23 GMT"
},
{
"version": "v3",
"created": "Fri, 17 Aug 2007 07:26:59 GMT"
},
{
"version": "v4",
"created": "Wed, 7 Nov 2007 10:50:46 GMT"
}
] | 2010-02-03T00:00:00 | [
[
"Gao",
"Xian",
""
]
] |
0708.1227 | Galina Korotkova Gennadievna | S. S. Kaisin, A. V. Kasparova, A. Yu. Knyazev, and I. D. Karachentsev | H-alpha Survey of the Local Volume: Isolated Southern Galaxies | 9 pages, 3 figures | Astron.Lett.33:283-291,2007 | 10.1134/S1063773707050015 | null | astro-ph | null | We present our H-alpha observations of 11 isolated southern galaxies: SDIG,
PGC 51659, E 222-010, E 272-025, E 137-018, IC 4662, Sag DIG, IC 5052, IC 5152,
UGCA 438, and E149-003, with distances from 1 to 7 Mpc. We have determined the
total H-alpha fluxes from these galaxies. The star formation rates in these
galaxies range from 10^{-1} (IC 4662) to 10^{-4}_{\odot}/yr (SDIG) and the gas
depletion time at the observed star formation rates lies within the range from
1/6 to 24 Hubble times H_0^{-1} .
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 10:11:59 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Kaisin",
"S. S.",
""
],
[
"Kasparova",
"A. V.",
""
],
[
"Knyazev",
"A. Yu.",
""
],
[
"Karachentsev",
"I. D.",
""
]
] |
0708.1228 | Dmitry Kerner | Dmitry Kerner | On the collisions of singular points of complex algebraic plane curves | Final version | "Contemporary Mathematics", volume 475, 2008, pg. 89-110 | null | null | math.AG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study the "generic" degenerations of curves with two singular points when
the points merge. First, the notion of generic degeneration is defined
precisely. Then a method to classify the possible results of generic
degenerations is proposed in the case of linear singularity types.
We discuss possible bounds on the singularity invariants of the resulting
type in terms of the initial types. In particular the strict upper bound on the
resulting multiplicity is proved and a sufficient condition for $\delta=const$
collision is given.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 08:56:32 GMT"
},
{
"version": "v2",
"created": "Tue, 27 May 2008 09:49:29 GMT"
},
{
"version": "v3",
"created": "Tue, 21 Apr 2009 17:09:23 GMT"
}
] | 2009-04-21T00:00:00 | [
[
"Kerner",
"Dmitry",
""
]
] |
0708.1229 | Dmitry Kerner | Dmitry Kerner | On the enumeration of complex plane curves with two singular points | 24 pages, the Mathematica file with explicit calculations is
attached. Some typos removed. To appear in the International Mathematics
Research Notices | International Mathematics Research Notices, 2010 | 10.1093/imrn/rnq057 | preprint: Max Planck Institut fuer Mathematik Bonn, Germany,
MPIM2007-76 | math.AG | http://arxiv.org/licenses/nonexclusive-distrib/1.0/ | We study equi-singular strata of plane curves with two singular points of
prescribed types. The method of the previous work [Kerner06] is generalized to
this case. In particular we consider the enumerative problem for plane curves
with two singular points of linear singularity types. First the problem for two
ordinary multiple points of fixed multiplicities is solved. Then the
enumeration for arbitrary linear types is reduced to the case of ordinary
multiple points and to the understanding of "merging" of singular points. Many
examples and numerical answers are given.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 09:05:11 GMT"
},
{
"version": "v2",
"created": "Thu, 27 Dec 2007 13:09:12 GMT"
},
{
"version": "v3",
"created": "Tue, 22 Jul 2008 16:42:31 GMT"
},
{
"version": "v4",
"created": "Tue, 20 Oct 2009 11:58:54 GMT"
},
{
"version": "v5",
"created": "Mon, 18 Jan 2010 07:39:49 GMT"
}
] | 2010-06-02T00:00:00 | [
[
"Kerner",
"Dmitry",
""
]
] |
0708.1230 | Fedor V. Prigara | Fedor V. Prigara | Antiferromagnetic fluctuations in the superconducting phase of low- and
high-temperature superconductors | 10 pages, REVTeX, Note on hole-doped cuprate superconductors added | null | null | null | cond-mat.supr-con | null | Based on recent experimental results for electron-doped cuprate oxides and
ferromagnetic superconductors, it is shown that antiferromagnetic fluctuations
always develop in the superconducting phase of both low- and high-temperature
superconductors. The relation between the magnitude of the antiferromagnetic
pseudogap and the characteristic temperature of the antiferromagnetic pseudogap
opening is obtained. The characteristic temperature of the antiferromagnetic
pseudogap opening for metal superconductors is estimated.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 09:09:04 GMT"
},
{
"version": "v2",
"created": "Wed, 22 Aug 2007 11:50:34 GMT"
},
{
"version": "v3",
"created": "Mon, 3 Sep 2007 10:35:05 GMT"
}
] | 2007-09-03T00:00:00 | [
[
"Prigara",
"Fedor V.",
""
]
] |
0708.1231 | Fei Huang | F. Huang, W.L. Wang, Z.Y. Zhang, Y.W. Yu | Preliminary study of the anti-K N interaction in a chiral constituent
quark model | 4 pages, 6 figures | Phys.Rev.C76:018201,2007 | 10.1103/PhysRevC.76.018201 | null | nucl-th | null | A preliminary investigation of the anti-K N interaction is performed within a
chiral constituent quark model by solving the resonating group method (RGM)
equation. The model parameters are taken from our previous work, which gave a
satisfactory description of the S-, P-, D-, F-wave KN scattering phase shifts.
The channel-coupling between anti-K N, pi Lambda and pi Sigma is considered,
and the scattering phase shifts as well as the bound-state problem of anti-K N
are dynamically studied. The results show that the S-wave anti-K N interaction
in the isospin I=0 channel is attractive, and in the extended chiral SU(3)
quark model such an attraction can make for an anti-K N bound state, which
appears as a pi Sigma resonance in the coupled-channel calculation, while the
chiral SU(3) quark model cannot accommodate the existence of an anti-K N bound
state. It seems that the vector meson exchanges are necessary to be introduced
in the quark-quark interactions if one tries to explain the Lambda(1405) as an
anti-K N bound state or a pi Sigma - anti-K N resonance state.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 09:13:37 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Huang",
"F.",
""
],
[
"Wang",
"W. L.",
""
],
[
"Zhang",
"Z. Y.",
""
],
[
"Yu",
"Y. W.",
""
]
] |
0708.1232 | Sarah Bailey Frick | Sarah Bailey Frick, Karl Petersen | Random permutations and unique fully supported ergodicity for the Euler
adic transformation | 12 pages, 7 figures, to appear Ann. Inst. H. Poincar\'e Prob. and
Stat | null | null | null | math.DS | null | There is only one fully supported ergodic invariant probability measure for
the adic transformation on the space of infinite paths in the graph that
underlies the Eulerian numbers. This result may partially justify a frequent
assumption about the equidistribution of random permutations.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 19:38:23 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Frick",
"Sarah Bailey",
""
],
[
"Petersen",
"Karl",
""
]
] |
0708.1233 | Gaurang Mahajan | Gaurang Mahajan, T. Padmanabhan | Particle creation, classicality and related issues in quantum field
theory: I. Formalism and toy models | RevTeX 4; 32 pages; 28 figures; first of a series of two papers, the
second being arXiv:0708.1237 [gr-qc]; high resolution figures available from
the authors on request | Gen.Rel.Grav. 40 (2008) 661-708 | 10.1007/s10714-007-0526-z | null | gr-qc astro-ph hep-th | null | The quantum theory of a harmonic oscillator with a time dependent frequency
arises in several important physical problems, especially in the study of
quantum field theory in an external background. While the mathematics of this
system is straightforward, several conceptual issues arise in such a study. We
present a general formalism to address some of the conceptual issues like the
emergence of classicality, definition of particle content, back reaction etc.
In particular, we parametrize the wave function in terms of a complex number
(which we call excitation parameter) and express all physically relevant
quantities in terms it. Many of the notions -- like those of particle number
density, effective Lagrangian etc., which are usually defined using asymptotic
in-out states -- are generalized as time-dependent concepts and we show that
these generalized definitions lead to useful and reasonable results. Having
developed the general formalism we apply it to several examples. Exact analytic
expressions are found for a particular toy model and approximate analytic
solutions are obtained in the extreme cases of adiabatic and highly
non-adiabatic evolution. We then work out the exact results numerically for a
variety of models and compare them with the analytic results and
approximations. The formalism is useful in addressing the question of emergence
of classicality of the quantum state, its relation to particle production and
to clarify several conceptual issues related to this. In Paper II
(arXiv:0708.1237), which is a sequel to this, the formalism will be applied to
analyze the corresponding issues in the context of quantum field theory in
background cosmological models and electric fields.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 10:16:29 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Mahajan",
"Gaurang",
""
],
[
"Padmanabhan",
"T.",
""
]
] |
0708.1234 | Benjamin Burrington A. | Benjamin A. Burrington, Vadim S. Kaplunovsky, Jacob Sonnenschein | Localized Backreacted Flavor Branes in Holographic QCD | 1+48 pages (7 figures) + 15 pages, citations added & minor
corrections | JHEP 0802:001,2008 | 10.1088/1126-6708/2008/02/001 | TAUP-2861/07 and UTTG-04-07 | hep-th | null | We investigate the perturbative (in $g_s N_{D8}$) backreaction of localized
D8 branes in D4-D8 systems including in particular the Sakai Sugimoto model. We
write down the explicit expressions of the backreacted metric, dilaton and RR
form. We find that the backreaction remains small up to a radial value of $u
\ll \ell_s/(g_s N_{D8})$, and that the background functions are smooth except
at the D8 sources. In this perturbative window, the original embedding remains
a solution to the equations of motion. Furthermore, the fluctuations around the
original embedding, describing scalar mesons, do not become tachyonic due to
the backreaction in the perturbative regime. This is is due to a cancelation
between the DBI and CS parts of the D8 brane action in the perturbed
background.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 09:14:46 GMT"
},
{
"version": "v2",
"created": "Thu, 29 Nov 2007 09:51:11 GMT"
},
{
"version": "v3",
"created": "Tue, 12 Feb 2008 09:38:23 GMT"
}
] | 2014-11-18T00:00:00 | [
[
"Burrington",
"Benjamin A.",
""
],
[
"Kaplunovsky",
"Vadim S.",
""
],
[
"Sonnenschein",
"Jacob",
""
]
] |
0708.1235 | Passemar Emilie | Emilie Passemar | Dispersive representation and shape of K_{l3} form factors | 7 pages, 4 figures. Discussion slightly extended in section 2. Talk
given at the KAON07 International Conference, May 21-25 2007, Frascati, Italy | PoSKAON:012,2008 | null | null | hep-ph hep-ex | null | The Callan-Treiman low-energy theorem offers an opportunity to test
electroweak couplings of light quarks to the gauge boson W. To that aim, we
introduce a model-independent and accurate dispersive parametrization of the
two K_{l3} form factors. We then discuss three applications to the analysis of
K_{e3} and K_{mu3} measurements: the prediction of the ratios
Gamma(K_{mu3})/Gamma(K_{e3}), the extraction of |f_+(0)V_{us}| and finally the
possible measurement of m_u - m_d induced isospin breaking asymmetry.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 19:47:14 GMT"
},
{
"version": "v2",
"created": "Mon, 29 Oct 2007 19:19:49 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Passemar",
"Emilie",
""
]
] |
0708.1236 | Carlo Rovelli | Jonathan Engle, Roberto Pereira, Carlo Rovelli | Flipped spinfoam vertex and loop gravity | 37 pages, 4 figures | Nucl.Phys.B798:251-290,2008 | 10.1016/j.nuclphysb.2008.02.002 | null | gr-qc | null | We introduce a vertex amplitude for 4d loop quantum gravity. We derive it
from a conventional quantization of a Regge discretization of euclidean general
relativity. This yields a spinfoam sum that corrects some difficulties of the
Barrett-Crane theory. The second class simplicity constraints are imposed
weakly, and not strongly as in Barrett-Crane theory. Thanks to a flip in the
quantum algebra, the boundary states turn out to match those of SO(3) loop
quantum gravity -- the two can be identified as eigenstates of the same
physical quantities -- providing a solution to the problem of connecting the
covariant SO(4) spinfoam formalism with the canonical SO(3) spin-network one.
The vertex amplitude is SO(3) and SO(4)-covariant. It rectifies the triviality
of the intertwiner dependence of the Barrett-Crane vertex, which is responsible
for its failure to yield the correct propagator tensorial structure. The
construction provides also an independent derivation of the kinematics of loop
quantum gravity and of the result that geometry is quantized.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 09:35:40 GMT"
}
] | 2008-11-26T00:00:00 | [
[
"Engle",
"Jonathan",
""
],
[
"Pereira",
"Roberto",
""
],
[
"Rovelli",
"Carlo",
""
]
] |
0708.1237 | Gaurang Mahajan | Gaurang Mahajan, T. Padmanabhan | Particle creation, classicality and related issues in quantum field
theory: II. Examples from field theory | RevTeX 4; 27 pages; 18 figures; second of a series of two papers, the
first being arXiv:0708.1233 [gr-qc]; high resolution figures available from
the authors on request | Gen.Rel.Grav. 40 (2008) 709-747 | 10.1007/s10714-007-0527-y | null | gr-qc astro-ph hep-th | null | We adopt the general formalism, which was developed in Paper I
(arXiv:0708.1233) to analyze the evolution of a quantized time-dependent
oscillator, to address several questions in the context of quantum field theory
in time dependent external backgrounds. In particular, we study the question of
emergence of classicality in terms of the phase space evolution and its
relation to particle production, and clarify some conceptual issues. We
consider a quantized scalar field evolving in a constant electric field and in
FRW spacetimes which illustrate the two extreme cases of late time adiabatic
and highly non-adiabatic evolution. Using the time-dependent generalizations of
various quantities like particle number density, effective Lagrangian etc.
introduced in Paper I, we contrast the evolution in these two limits bringing
out key differences between the Schwinger effect and evolution in the de Sitter
background. Further, our examples suggest that the notion of classicality is
multifaceted and any one single criterion may not have universal applicability.
For example, the peaking of the phase space Wigner distribution on the
classical trajectory \emph{alone} does not imply transition to classical
behavior. An analysis of the behavior of the \emph{classicality parameter},
which was introduced in Paper I, leads to the conclusion that strong particle
production is necessary for the quantum state to become highly correlated in
phase space at late times.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 10:23:30 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Mahajan",
"Gaurang",
""
],
[
"Padmanabhan",
"T.",
""
]
] |
0708.1238 | Hyun Jong Shin | H. J. Shin | Three-dimensional Curve Motions Induced by the Modified Korteweg-de
Vries Equation | 26 pages, 4 figures | null | 10.1143/PTP.119.701 | null | nlin.SI | null | We have constructed one-phase quasi-periodic solutions of the curve equation
induced by the mKdV equation. The solution is expressed in terms of the
elliptic functions of Weierstrass. This solution can describe curve dynamics
such as a vortex filament with axial velocity embedded in an incompressible
inviscid fluid. There exist two types of curves (type-A, type-B) according to
the form of the main spectra of the finite-band integrated solution. Our
solution includes various filament shapes such as the Kelvin-type wave, the
rigid vortex, plane curves, closed curves, and the Hasimoto one-solitonic
filament.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 09:45:02 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Shin",
"H. J.",
""
]
] |
0708.1239 | Nicola Cufaro Petroni | Nicola Cufaro Petroni | Selfdecomposability and selfsimilarity: a concise primer | 24 pages, 3 figures; corrected misprint in the title; redactional
modifications required by the referee; added references from [16] to [28];.
Accepted and in press on Physica A | Physica A 387 (2008) 1875-94 | 10.1016/j.physa.2007.11.036 | Rapporto n. 32/07 - Dpt of Mathematics, Bari University | cond-mat.stat-mech math.PR | null | We summarize the relations among three classes of laws: infinitely divisible,
selfdecomposable and stable. First we look at them as the solutions of the
Central Limit Problem; then their role is scrutinized in relation to the Levy
and the additive processes with an emphasis on stationarity and selfsimilarity.
Finally we analyze the Ornstein-Uhlenbeck processes driven by Levy noises and
their selfdecomposable stationary distributions, and we end with a few
particular examples.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 09:45:44 GMT"
},
{
"version": "v2",
"created": "Fri, 10 Aug 2007 18:33:14 GMT"
},
{
"version": "v3",
"created": "Tue, 27 Nov 2007 22:03:31 GMT"
}
] | 2008-05-06T00:00:00 | [
[
"Petroni",
"Nicola Cufaro",
""
]
] |
0708.1240 | Alvio Renzini | Alvio Renzini | The Rest-Frame UV Spectrum of Elliptical Galaxies at High Redshift | 9 pages, 6 figures, invited talk at the conference "New Quests in
Stellar Astrophysics II: The Ultraviolet Properties of Evolved Stellar
Populations", Puerto Vallarta, Mexico, April 16-20, 2007. Proceedings edited
by Miguel Chavez-Dagostino | null | 10.1007/978-0-387-87621-4_1 | null | astro-ph | null | Beyond redshift ~1.4 the only spectral feature that allows one to get the
redshift of passively evolving galaxies (PEG) with optical spectrographs is a
characteristic structure due to a set of iron and magnesium lines lines at
2600-2850 Angstrom in the rest frame. The same feature permits also to estimate
the time elapsed since the cessation of star formation. Current efforts at
observing high redshift PEGs at the VLT and SUBARU telescopes are briefly
reviewed.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 09:52:25 GMT"
}
] | 2020-08-05T00:00:00 | [
[
"Renzini",
"Alvio",
""
]
] |
0708.1241 | Igor Mazin | I.I. Mazin | Absence of magnetic ordering in NiGa_2S_4 | 4 pages, 4 figures | Phys. Rev. B 76, 140406(R) (2007) | 10.1103/PhysRevB.76.140406 | null | cond-mat.str-el cond-mat.mtrl-sci | null | Triangular-layered NiGa2S4, contrary to intuitive expectation, does not form
a noncollinear antiferromagnetic structure, as do isoelectronic NaCrO2 and
LiCrO2. Instead, the local magnetic moments remain disordered down to the
lowest measured temperature. To get more insight into this phenomenon, we have
performed first principles calculations of the first, second end third
neighbors exchange interactions, and found that the second neighbor exchange is
negligible, while the first and the third neighbor exchanges are comparable and
antiferromagnetic. Both are rapidly suppressed by the on-site Hubbard
repulsion.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 18:48:01 GMT"
}
] | 2015-05-13T00:00:00 | [
[
"Mazin",
"I. I.",
""
]
] |
0708.1242 | Christos Dimitrakakis | Christos Dimitrakakis and Christian Savu-Krohn | Cost-minimising strategies for data labelling : optimal stopping and
active learning | 17 pages, 4 figures. Corrected some errors and changed the flow of
the text | null | null | null | cs.LG | null | Supervised learning deals with the inference of a distribution over an output
or label space $\CY$ conditioned on points in an observation space $\CX$, given
a training dataset $D$ of pairs in $\CX \times \CY$. However, in a lot of
applications of interest, acquisition of large amounts of observations is easy,
while the process of generating labels is time-consuming or costly. One way to
deal with this problem is {\em active} learning, where points to be labelled
are selected with the aim of creating a model with better performance than that
of an model trained on an equal number of randomly sampled points. In this
paper, we instead propose to deal with the labelling cost directly: The
learning goal is defined as the minimisation of a cost which is a function of
the expected model performance and the total cost of the labels used. This
allows the development of general strategies and specific algorithms for (a)
optimal stopping, where the expected cost dictates whether label acquisition
should continue (b) empirical evaluation, where the cost is used as a
performance metric for a given combination of inference, stopping and sampling
methods. Though the main focus of the paper is optimal stopping, we also aim to
provide the background for further developments and discussion in the related
field of active learning.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 10:21:34 GMT"
},
{
"version": "v2",
"created": "Mon, 27 Aug 2007 22:05:57 GMT"
},
{
"version": "v3",
"created": "Thu, 15 Nov 2007 16:37:51 GMT"
}
] | 2007-11-15T00:00:00 | [
[
"Dimitrakakis",
"Christos",
""
],
[
"Savu-Krohn",
"Christian",
""
]
] |
0708.1243 | Alvio Renzini | Alvio Renzini | New HST Views at Old Stellar Systems | 8 pages, 7 figures, invited talk at the 41st ESLAB Symposium: The
Impact of HST on European Astronomy, Noordwijk, Netherland, May 29-June 1,
2007 | null | null | null | astro-ph | null | HST has recently revealed that many among the most massive globular clusters
harbor multiple stellar populations, and --most surprisingly-- some of them are
extremely helium rich. How these clusters managed to generate such complex
stellar populations, and what processes let to so dramatic helium enrichment,
is today one of the most exciting puzzles in the astrophysics of stellar
systems. HST has also been instrumental in demonstrating that both the bulge of
our own Galaxy and that of M31 are dominated by old stellar populations, coeval
to galactic globular clusters. Ultradeep HST imaging has also demonstrated that
a major component of the M31 halo is metal rich and much younger than old
globular clusters.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 10:44:17 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Renzini",
"Alvio",
""
]
] |
0708.1244 | Peter Franek | Peter Franek | Several Dirac Operator in parabolic geometry | null | null | null | null | math.DG | null | In this thesis, we show the existence of a sequence of differential operators
starting with with the Dirac operator in k Clifford variables, $D=(D_1,...,
D_k)$, where $D_i=\sum_j e_j\cdot \partial_{ij}: C^\infty((\R^n)^k,\S)\to
C^\infty((\R^n)^k,\S)$ ($\S$ is the spinor module). This operator is the
Cauchy-Riemann operator for n=2 and its resolution is the Dolbeault complex.
For higher n, the resolution of D is not known in general. While this problem
was treated many times in the language of Clifford analysis and some partial
results are known, we give a description of this operator in Parabolic
geometry, which is a special type of Cartan geometry modeled on $G/P$, where P
is a Parabolic subgroup of G. We construct sequences of invariant differential
operators starting with the Dirac operator in several variables and assume that
these sequences coinside in some cases with the resolution. We describe the
structure of these sequences precisely in case the dimension $n$ is odd and
give a conjecture that these sequences have similar structure for n even,
$k\leq n/2$ (the s.c. {\it stable range}). We also give some information about
these sequences in case n even, k>n/2. In the last chapter, explicite formulas
for the operators are derived for the case k=2.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 10:55:22 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Franek",
"Peter",
""
]
] |
0708.1245 | Jens Marklof | Jens Marklof, Yves Tourigny, Lech Wolowski | Pade approximants of random Stieltjes series | To appear in Proc Roy Soc | null | 10.1098/rspa.2007.0014 | null | math-ph math.MP math.NA | null | We consider the random continued fraction S(t) := 1/(s_1 + t/(s_2 + t/(s_3 +
>...))) where the s_n are independent random variables with the same gamma
distribution. For every realisation of the sequence, S(t) defines a Stieltjes
function. We study the convergence of the finite truncations of the continued
fraction or, equivalently, of the diagonal Pade approximants of the function
S(t). By using the Dyson--Schmidt method for an equivalent one-dimensional
disordered system, and the results of Marklof et al. (2005), we obtain explicit
formulae (in terms of modified Bessel functions) for the almost-sure rate of
convergence of these approximants, and for the almost-sure distribution of
their poles.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 10:57:04 GMT"
}
] | 2009-11-13T00:00:00 | [
[
"Marklof",
"Jens",
""
],
[
"Tourigny",
"Yves",
""
],
[
"Wolowski",
"Lech",
""
]
] |
0708.1246 | Raphael Rouquier | C\'edric Bonnaf\'e and Rapha\"el Rouquier | Affineness of Deligne-Lusztig varieties for minimal length elements | Corrected version | null | null | null | math.AG math.RT | null | We prove that the Deligne-Lusztig varieties associated to elements of the
Weyl group which are of minimal length in their twisted class are affine. Our
proof differs from the proof of He and Orlik-Rapoport and it is inspired by the
case of regular elements, which correspond to the varieties involved in
Brou\'e's conjectures.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 10:58:47 GMT"
},
{
"version": "v2",
"created": "Mon, 3 Dec 2007 11:15:48 GMT"
}
] | 2007-12-03T00:00:00 | [
[
"Bonnafé",
"Cédric",
""
],
[
"Rouquier",
"Raphaël",
""
]
] |
0708.1247 | Sanjay Ram | Md. N. Islam, Sanjay K. Ram and Satyendra Kumar | Band edge discontinuities and carrier transport in c-Si/porous silicon
heterojunctions | 8 pages, 11 figures | null | null | null | cond-mat.mtrl-sci | null | We have prepared light emitting nanocrystalline porous silicon (PS) layers by
electrochemical anodization of crystalline silicon (c-Si) wafer and
characterized the c-Si/PS heterojunctions using temperature dependence of dark
current-voltage (I-V) characteristics. The reverse bias I-V characteristics of
c-Si/PS heterojunctions are found to behave like Schottky junctions where
carrier transport is mainly governed by the carrier generation-recombination in
the depletion region formed on the PS side. Fermi level of c-Si gets pinned to
the defect levels at the interface resulting in ln(I) proportional to V^0.5.
The barrier height in the reverse bias condition is shown to be equal to the
band offset at the conduction band edges. An energy band diagram for the
c-Si/PS heterojunction is proposed.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 11:10:34 GMT"
}
] | 2007-08-10T00:00:00 | [
[
"Islam",
"Md. N.",
""
],
[
"Ram",
"Sanjay K.",
""
],
[
"Kumar",
"Satyendra",
""
]
] |
0708.1248 | Konstantinos Zoubos | James Bedford, Constantinos Papageorgakis and Konstantinos Zoubos | Twistor Strings with Flavour | 38+12 pages; uses axodraw.sty. v2: References added, minor
clarifications | JHEP 0711:088,2007 | 10.1088/1126-6708/2007/11/088 | QMUL-PH-07-13, CERN-PH-TH/2007-117, TIFR/TH/07-13 | hep-th | null | We explore the tree-level description of a class of N=2 UV-finite SYM
theories with fundamental flavour within a topological B-model twistor string
framework. In particular, we identify the twistor dual of the Sp(N) gauge
theory with one antisymmetric and four fundamental hypermultiplets, as well as
that of the SU(N) theory with 2N hypermultiplets. This is achieved by suitably
orientifolding/orbifolding the original N=4 setup of Witten and adding a
certain number of new topological 'flavour'-branes at the orientifold/orbifold
fixed planes to provide the fundamental matter. We further comment on the
appearance of these objects in the B-model on CP(3|4). An interesting aspect of
our construction is that, unlike the IIB description of these theories in terms
of D3 and D7-branes, on the twistor side part of the global flavour symmetry is
realised geometrically. We provide evidence for this correspondence by
calculating and matching amplitudes on both sides.
| [
{
"version": "v1",
"created": "Thu, 9 Aug 2007 16:00:23 GMT"
},
{
"version": "v2",
"created": "Wed, 5 Sep 2007 09:59:06 GMT"
}
] | 2014-11-18T00:00:00 | [
[
"Bedford",
"James",
""
],
[
"Papageorgakis",
"Constantinos",
""
],
[
"Zoubos",
"Konstantinos",
""
]
] |
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