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802.2403 | Hylke Koers | Hylke B. J. Koers, Peter Tinyakov | Koers Hylke B. J., Tinyakov Peter | On the relation between the neutrino flux from Centaurus A and the
associated diffuse neutrino flux | 12 pages, 5 figures, revtex4. Accepted for publication in PRD. (v2)
Expanded significantly compared to the previous version; conclusions remain
valid | Phys.Rev.D78:083009,2008 | 10.1103/PhysRevD.78.083009 | astro-ph hep-ph | Based on recent results obtained by the Pierre Auger Observatory (PAO), it
has been hypothesized that Centaurus A (Cen A) is a source of ultra-high-energy
cosmic rays (UHECRs) and associated neutrinos. We point out that the diffuse
neutrino flux may be used to constrain the source model if one assumes that the
ratio between the UHECR and neutrino fluxes outputted by Cen A is
representative for other sources. Under this assumption we investigate the
relation between the neutrino flux from Cen A and the diffuse neutrino flux.
Assuming furthermore that Cen A is the source of two UHECR events observed by
PAO, we estimate the all-sky diffuse neutrino flux to be ~200-5000 times larger
than the neutrino flux from Cen A. As a result, the diffuse neutrino fluxes
associated with some of the recently proposed models of UHECR-related neutrino
production in Cen A are above existing limits. Regardless of the underlying
source model, our results indicate that the detection of neutrinos from Cen A
without the accompanying diffuse flux would mean that Cen A is an exceptionally
efficient neutrino source.
| v1 (Mon, 18 Feb 2008 20:05:05 GMT), v2 (Sun, 5 Oct 2008 17:06:38 GMT) |
802.2404 | Aaron O'Connell | Aaron D. O'Connell, M. Ansmann, R. C. Bialczak, M. Hofheinz, N. Katz,
Erik Lucero, C. McKenney, M. Neeley, H. Wang, E. M. Weig, A. N. Cleland, and
J. M. Martinis | O'Connell Aaron D., Ansmann M., Bialczak R. C., Hofheinz M., Katz N., Lucero Erik, McKenney C., Neeley M., Wang H., Weig E. M., Cleland A. N., Martinis J. M. | Microwave Dielectric Loss at Single Photon Energies and milliKelvin
Temperatures | 4 pages, 3 figures, submitted to Applied Physics Letters | null | 10.1063/1.2898887 | cond-mat.supr-con | The microwave performance of amorphous dielectric materials at very low
temperatures and very low excitation strengths displays significant excess
loss. Here, we present the loss tangents of some common amorphous and
crystalline dielectrics, measured at low temperatures (T < 100 mK) with near
single-photon excitation energies, using both coplanar waveguide (CPW) and
lumped LC resonators. The loss can be understood using a two-level state (TLS)
defect model. A circuit analysis of the half-wavelength resonators we used is
outlined, and the energy dissipation of such a resonator on a multilayered
dielectric substrate is considered theoretically.
| v1 (Mon, 18 Feb 2008 00:38:50 GMT) |
802.2405 | Scott Fleming | S.W. Fleming, S.R. Kane, P.R. McCullough, F.R. Chromey | Fleming S. W., Kane S. R., McCullough P. R., Chromey F. R. | Detecting "Temperate" Jupiters: The Prospects of Searching for
Transiting Gas Giants in Habitability Zones | 14 pages, 12 figures, 4 tables, accepted to MNRAS | null | 10.1111/j.1365-2966.2008.13120.x | astro-ph | This paper investigates the effects of observing windows on detecting
transiting planets by calculating the fraction of planets with a given period
that have zero, one (single), two (double), or $\ge$3 (multiple) transits
occurring while observations are being taken. We also investigate the effects
of collaboration by performing the same calculations with combined observing
times from two wide-field transit survey groups. For a representative field of
the 2004 observing season, both XO and SuperWASP experienced an increase in
single and double transit events by up to 20-40% for planets with periods 14 <
P < 150 days when collaborating by sharing data. For the XO Project using its
data alone, between 20-40% of planets with periods 14-150 days should have been
observed at least once. For the SuperWASP Project, 50-90% of planets with
periods between 14-150 days should have been observed at least once. If XO and
SuperWASP combined their observations, 50-100% of planets with periods less
than 20 days should be observed three or more times. We find that in general
wide-field transit surveys have selected appropriate observing strategies to
observe a significant fraction of transiting giant planets with semimajor axes
larger than the Hot Jupiter regime. The actual number of intermediate-period
transiting planets that are detected depends upon their true semimajor axis
distribution and the signal-to-noise of the data.
| v1 (Mon, 18 Feb 2008 01:09:43 GMT) |
802.2406 | Reg Cahill | Reginald T Cahill, Finn Stokes (Flinders University) | Cahill Reginald T, Stokes Finn | Correlated Detection of sub-mHz Gravitational Waves by Two Optical-Fiber
Interferometers | 15 pages, 17 colored figures | Progr.Phys.2:103-110,2008 | null | physics.gen-ph | Results from two optical-fiber gravitational-wave interferometric detectors
are reported. The detector design is very small, cheap and simple to build and
operate. Using two detectors has permitted various tests of the design
principles as well as demonstrating the first simultaneous detection of
correlated gravitational waves from detectors spatially separated by 1.1km. The
frequency spectrum of the detected gravitational waves is sub-mHz with a strain
spectral index a=-1.4 +/- 0.1. As well as characterising the wave effects the
detectors also show, from data collected over some 80 days in the latter part
of 2007, the dominant earth rotation effect and the earth orbit effect. The
detectors operate by exploiting light speed anisotropy in optical-fibers. The
data confirms previous observations of light speed anisotropy, earth rotation
and orbit effects, and gravitational waves.
| v1 (Mon, 18 Feb 2008 01:09:08 GMT) |
802.2407 | Alexej Bagrets | Chen Li, Ilya Pobelov, Thomas Wandlowski, Alexei Bagrets, Andreas
Arnold, and Ferdinand Evers | Li Chen, Pobelov Ilya, Wandlowski Thomas, Bagrets Alexei, Arnold Andreas, Evers Ferdinand | Charge Transport in Single Au|Alkanedithiol|Au Junctions: Coordination
Geometries and Conformational Degrees of Freedom | 19 pages, 9 figures, 1 table; published version | J. Am. Chem. Soc. 2008, 130, 318-326 | 10.1021/ja0762386 | cond-mat.mtrl-sci | Recent STM molecular break-junction experiments have revealed multiple series
of peaks in the conductance histograms of alkanedithiols. To resolve a current
controversy, we present here an in-depth study of charge transport properties
of Au|alkanedithiol|Au junctions. Conductance histograms extracted from our STM
measurements unambiguously confirm features showing more than one set of
junction configurations. Based on quantum chemistry calculations, we propose
that certain combinations of different sulfur-gold couplings and trans/gauche
conformations act as the driving agents. The present study may have
implications for experimental methodology: whenever conductances of different
junction conformations are not statistically independent, the conductance
histogram technique can exhibit a single series only, even though a much larger
abundance of microscopic realizations exists.
| v1 (Mon, 18 Feb 2008 01:20:06 GMT) |
802.2408 | Terence C. Tao | Terence Tao | Tao Terence | Why are solitons stable? | 33 pages, no figures, submitted, Bulletin of the AMS. Minor
corrections | null | null | math.AP | The theory of linear dispersive equations predicts that waves should spread
out and disperse over time. However, it is a remarkable phenomenon, observed
both in theory and practice, that once nonlinear effects are taken into
account, \emph{solitary wave} or \emph{soliton} solutions can be created, which
can be stable enough to persist indefinitely. The construction of such
solutions is relatively straightforward, but the fact that they are
\emph{stable} requires some significant amounts of analysis to establish, in
part due to symmetries in the equation (such as translation invariance) which
create degeneracy in the stability analysis. The theory is particularly
difficult in the \emph{critical} case in which the nonlinearity is at exactly
the right power to potentially allow for a self-similar blowup. In this article
we survey some of the highlights of this theory, from the more classical
orbital stability analysis of Weinstein and Grillakis-Shatah-Strauss, to the
more recent asymptotic stability and blowup analysis of Martel-Merle and
Merle-Raphael, as well as current developments in using this theory to
rigorously demonstrate controlled blowup for several key equations.
| v1 (Mon, 18 Feb 2008 02:26:54 GMT), v2 (Wed, 20 Feb 2008 18:43:48 GMT) |
802.2409 | Youngman Kim | Youngman Kim and Hyun Kyu Lee | Kim Youngman, Lee Hyun Kyu | Consequences of the partial restoration of chiral symmetry in AdS/QCD | 11 pages, 6 figures | Phys.Rev.D77:096011,2008 | 10.1103/PhysRevD.77.096011 | hep-ph | Chiral symmetry is an essential concept in understanding QCD at low energy.
We treat the chiral condensate, which measures the spontaneous breaking of
chiral symmetry, as a free parameter to investigate the effect of partially
restored chiral symmetry on the physical quantities in the frame work of an
AdS/QCD model. We observe an interesting scaling behavior among the nucleon
mass, pion decay constant and chiral condensate. We propose a phenomenological
way to introduce the temperature dependence of a physical quantity in the
AdS/QCD model with the thermal AdS metric.
| v1 (Mon, 18 Feb 2008 02:44:31 GMT) |
802.241 | Lev Kaplan | L. Kaplan and Y. Alhassid | Kaplan L., Alhassid Y. | Interaction Matrix Element Fluctuations in Ballistic Quantum Dots:
Random Wave Model | 13 pages, 10 figures | Phys. Rev. B 78, 085305 (2008) | 10.1103/PhysRevB.78.085305 | cond-mat.mes-hall nlin.CD nucl-th | We study matrix element fluctuations of the two-body screened Coulomb
interaction and of the one-body surface charge potential in ballistic quantum
dots. For chaotic dots, we use a normalized random wave model to obtain
analytic expansions for matrix element variances and covariances in the limit
of large kL (where k is the Fermi wave number and L the linear size of the
dot). These leading-order analytical results are compared with exact numerical
results. Both two-body and one-body matrix elements are shown to follow
strongly non-Gaussian distributions, despite the Gaussian random nature of the
single-electron wave functions.
| v1 (Mon, 18 Feb 2008 03:36:30 GMT) |
802.2411 | Mahesh Pal Dr. | Mahesh Pal | Pal Mahesh | Multiclass Approaches for Support Vector Machine Based Land Cover
Classification | 16 pages, MapIndia 2005 conference | null | null | cs.NE cs.CV | SVMs were initially developed to perform binary classification; though,
applications of binary classification are very limited. Most of the practical
applications involve multiclass classification, especially in remote sensing
land cover classification. A number of methods have been proposed to implement
SVMs to produce multiclass classification. A number of methods to generate
multiclass SVMs from binary SVMs have been proposed by researchers and is still
a continuing research topic. This paper compares the performance of six
multi-class approaches to solve classification problem with remote sensing data
in term of classification accuracy and computational cost. One vs. one, one vs.
rest, Directed Acyclic Graph (DAG), and Error Corrected Output Coding (ECOC)
based multiclass approaches creates many binary classifiers and combines their
results to determine the class label of a test pixel. Another catogery of multi
class approach modify the binary class objective function and allows
simultaneous computation of multiclass classification by solving a single
optimisation problem. Results from this study conclude the usefulness of One
vs. One multi class approach in term of accuracy and computational cost over
other multi class approaches.
| v1 (Mon, 18 Feb 2008 03:47:45 GMT) |
802.2412 | Yasuhiro Shimizu | Mihoko M. Nojiri, Yasuhiro Shimizu, Shogo Okada, Kiyotomo Kawagoe | Nojiri Mihoko M., Shimizu Yasuhiro, Okada Shogo, Kawagoe Kiyotomo | Inclusive transverse mass analysis for squark and gluino mass
determination | 21 pages, 18 figures | JHEP0806:035,2008 | 10.1088/1126-6708/2008/06/035 | hep-ph | We propose an inclusive analysis of a stransverse mass (m_{T2}) using a
hemisphere method for supersymmetry studies at the LHC . The hemisphere method
is an algorithm to group collinear and high p_T particles and jets, assuming
that there are two of such groups in a event. The m_{T2} is defined as a
function of the unknown LSP mass, two hemisphere momenta, and missing
transverse momentum. The kinematical end point of the m_{T2} distribution
provides information on the squark and gluino masses. We perform a Monte Carlo
simulation to study the inclusive m_{T2} distribution at the LHC. We show that
the end point of the inclusive m_{T2} distribution has a cusp-like structure
around the true LSP mass. The knowledge of the expected kinematical behavior
near the end point for true events is important to establish the end point of
the inclusive distribution. We find that the inclusive analysis is useful to
obtain the information on the heaviest of the squark/gluino.
| v1 (Mon, 18 Feb 2008 04:03:01 GMT) |
802.2413 | Masanari Asano | Tatsuro Yamamoto, Masanari Asano, Yoshio Togawa and Masanori Ohya | Yamamoto Tatsuro, Asano Masanari, Togawa Yoshio, Ohya Masanori | On the Scarf-Hirota model in the price-scaled price adjustment process | null | null | null | math.DS | Hirota's results given in (Hirota.M.,1981) on the asymptotically stability
are generalized to the price-scaled price adjustment process.
| v1 (Mon, 18 Feb 2008 04:10:12 GMT) |
802.2414 | Minhsiu Hsieh | Isaac Kremsky, Min-Hsiu Hsieh, and Todd A. Brun | Kremsky Isaac, Hsieh Min-Hsiu, Brun Todd A. | Classical Enhancement of Quantum Error-Correcting Codes | 8 pages, submitted to PRA | Phys. Rev. A 78, 012341 (2008) | 10.1103/PhysRevA.78.012341 | quant-ph | We present a general formalism for quantum error-correcting codes that encode
both classical and quantum information (the EACQ formalism). This formalism
unifies the entanglement-assisted formalism and classical error correction, and
includes encoding, error correction, and decoding steps such that the encoded
quantum and classical information can be correctly recovered by the receiver.
We formally define this kind of quantum code using both stabilizer and
symplectic language, and derive the appropriate error-correcting conditions. We
give several examples to demonstrate the construction of such codes.
| v1 (Mon, 18 Feb 2008 04:12:18 GMT) |
802.2415 | Leonid Kitchatinov | L. L. Kitchatinov, G. R\"udiger | Kitchatinov L. L., Rüdiger G. | Diamagnetic pumping near the base of a stellar convection zone | 4 pages, 5 figures | null | 10.1002/asna.200810971 | astro-ph | The property of inhomogeneous turbulence in conducting fluids to expel
large-scale magnetic fields in the direction of decreasing turbulence intensity
is shown as important for the magnetic field dynamics near the base of a
stellar convection zone. The downward diamagnetic pumping confines a fossil
internal magnetic field in the radiative core so that the field geometry is
appropriate for formation of the solar tachocline. For the stars of solar age,
the diamagnetic confinement is efficient only if the ratio of turbulent
magnetic diffusivity of the convection zone to the (microscopic or turbulent)
diffusivity of the radiative interiour is larger than 10^5. Confinement in
younger stars require still larger diffusivity ratio. The observation of
persistent magnetic structures on young solar-type stars can thus provide
evidences for the nonexistence of tachoclines in stellar interiors and on the
level of turbulence in radiative cores.
| v1 (Mon, 18 Feb 2008 05:15:06 GMT) |
802.2416 | Pengjie Zhang | Pengjie Zhang (SHAO) | Zhang Pengjie | Self calibration of galaxy bias in spectroscopic redshift surveys of
baryon acoustic oscillations | 7 pages, 3 figures. Submitted to ApJ | null | null | astro-ph | Baryon acoustic oscillation (BAO) is a powerful probe on the expansion of the
universe, shedding light on elusive dark energy and gravity at cosmological
scales. BAO measurements through biased tracers of the underlying matter
density field, as most proposals do, can reach high statistical accuracy.
However, possible scale dependence in bias may induce non-negligible
systematical errors, especially for the most ambitious spectroscopic surveys
proposed. We show that precision spectroscopic redshift information available
in these surveys allows for {\it self calibration} of the galaxy bias and its
stochasticity, as function of scale and redshift. Through the effect of
redshift distortion, one can simultaneously measure the real space power
spectra of galaxies, galaxy-velocity and velocity, respectively. At relevant
scales of BAO, galaxy velocity faithfully traces that of the underlying matter.
This valuable feature enables a rather model independent way to measure the
galaxy bias and its stochasticity by comparing the three power spectra. For the
square kilometer array (SKA), this self calibration is statistically accurate
to correct for 1% level shift in BAO peak positions induced by bias scale
dependence. Furthermore, we find that SKA is able to detect BAO in the velocity
power spectrum, opening a new window for BAO cosmology.
| v1 (Mon, 18 Feb 2008 05:32:09 GMT) |
802.2417 | Pengjie Zhang | Pengjie Zhang (SHAO) | Zhang Pengjie | Dimming of supernovae and gamma ray busts by Compton Scattering and its
cosmological implications | 3 pages, 3 figures. Minor revisions. Accepted to ApJ | Astrophys.J.682:721-723,2008 | 10.1086/589736 | astro-ph | Free electrons deplete photons from type Ia supernovae through the (inverse)
Compton scattering. This Compton dimming increases with redshift and reaches
0.004 mag at $z=1$ and 0.01 mag at $z=2$. Although far from sufficient to
invalidate the existence of dark energy, it can bias constraint on dark energy
at a level non-negligible for future supernova surveys. This effect is
correctable and should be incorporated in supernova analysis. The Compton
dimming has similar impact on cosmology based on gamma ray bursts as standard
candles.
| v1 (Mon, 18 Feb 2008 05:26:38 GMT), v2 (Thu, 10 Apr 2008 01:38:52 GMT) |
802.2418 | Jacob Scott | Christopher Crutchfield, Zoran Dzunic, Jeremy T. Fineman, David R.
Karger, and Jacob Scott | Crutchfield Christopher, Dzunic Zoran, Fineman Jeremy T., Karger David R., Scott Jacob | Improved Approximations for Multiprocessor Scheduling Under Uncertainty | null | null | null | cs.DC cs.DS | This paper presents improved approximation algorithms for the problem of
multiprocessor scheduling under uncertainty, or SUU, in which the execution of
each job may fail probabilistically. This problem is motivated by the
increasing use of distributed computing to handle large, computationally
intensive tasks. In the SUU problem we are given n unit-length jobs and m
machines, a directed acyclic graph G of precedence constraints among jobs, and
unrelated failure probabilities q_{ij} for each job j when executed on machine
i for a single timestep. Our goal is to find a schedule that minimizes the
expected makespan, which is the expected time at which all jobs complete.
Lin and Rajaraman gave the first approximations for this NP-hard problem for
the special cases of independent jobs, precedence constraints forming disjoint
chains, and precedence constraints forming trees. In this paper, we present
asymptotically better approximation algorithms. In particular, we give an
O(loglog min(m,n))-approximation for independent jobs (improving on the
previously best O(log n)-approximation). We also give an O(log(n+m) loglog
min(m,n))-approximation algorithm for precedence constraints that form disjoint
chains (improving on the previously best
O(log(n)log(m)log(n+m)/loglog(n+m))-approximation by a (log n/loglog n)^2
factor when n = poly(m). Our algorithm for precedence constraints forming
chains can also be used as a component for precedence constraints forming
trees, yielding a similar improvement over the previously best algorithms for
trees.
| v1 (Mon, 18 Feb 2008 20:57:17 GMT), v2 (Tue, 19 Feb 2008 02:58:36 GMT) |
802.2419 | Shun Watanabe | Shun Watanabe, Ryutaroh Matsumoto, Tomohiko Uyematsu | Watanabe Shun, Matsumoto Ryutaroh, Uyematsu Tomohiko | Tomography increases key rates of quantum-key-distribution protocols | 13 pages, 1 figure, REVTeX4. To be published in PRA. Version 2 adds
many references, a closed form key rate formula for unital channels, and a
procedure for the maximum likelihood channel estimation | Phys. Rev. A 78, 042316 (2008) | 10.1103/PhysRevA.78.042316 | quant-ph | We construct a practically implementable classical processing for the BB84
protocol and the six-state protocol that fully utilizes the accurate channel
estimation method, which is also known as the quantum tomography. Our proposed
processing yields at least as high key rate as the standard processing by Shor
and Preskill. We show two examples of quantum channels over which the key rate
of our proposed processing is strictly higher than the standard processing. In
the second example, the BB84 protocol with our proposed processing yields a
positive key rate even though the so-called error rate is higher than the 25%
limit.
| v1 (Mon, 18 Feb 2008 06:26:38 GMT), v2 (Tue, 22 Jul 2008 09:57:59 GMT) |
802.242 | Hitoshi Seo | Hitoshi Seo, Shoji Ishibashi, Yoshinori Okano, Hayao Kobayashi, Akiko
Kobayashi, Hidetoshi Fukuyama, and Kiyoyuki Terakura | Seo Hitoshi, Ishibashi Shoji, Okano Yoshinori, Kobayashi Hayao, Kobayashi Akiko, Fukuyama Hidetoshi, Terakura Kiyoyuki | Single-Component Molecular Metals as Multiband \pi-d Systems | 5 pages, 4 figures; for full color figures, see J. Phys. Soc. Jpn.
published version | J. Phys. Soc. Jpn. Vol. 77 No. 2, February, 2008, 023714 (4 pages) | 10.1143/JPSJ.77.023714 | cond-mat.str-el cond-mat.mtrl-sci | Electronic states of single-component molecular metals M(tmdt)2 (M = Ni, Au)
are studied theoretically. We construct an effective three-band Hubbard model
for each material by numerical fitting to first-principles band calculations,
while referring to molecular orbital calculations for the isolated molecules.
The model consists of two kinds of base orbital for each molecule with
hybridization between them, i.e., a \pi-character orbital for each of the two
tmdt ligands, and, a pd\pi-orbital for M = Ni or a pd\sigma-orbital for M = Au
centered on the metal site; this indicates that these materials can be
considered as novel multiband \pi-d systems. We find that both orbitals
contribute to realize the metallic character in Ni(tmdt)2. The origin of the
antiferromagnetic transition observed in Au(tmdt)2 is also discussed based on
this model.
| v1 (Mon, 18 Feb 2008 06:23:36 GMT) |
802.2421 | Juergen Horbach | Antoine Carre (University of Mainz, Germany), Juergen Horbach (German
Aerospace Center, Koeln, Germany), Simona Ispas, Walter Kob (University of
Montpellier II, France) | Carre Antoine, Horbach Juergen, Ispas Simona, Kob Walter | New fitting scheme to obtain effective potential from Car-Parrinello
molecular dynamics simulations: Application to silica | 6 pages, 5 figures | null | 10.1209/0295-5075/82/17001 | cond-mat.dis-nn cond-mat.mtrl-sci | A fitting scheme is proposed to obtain effective potentials from
Car-Parrinello molecular dynamics (CPMD) simulations. It is used to
parameterize a new pair potential for silica. MD simulations with this new
potential are done to determine structural and dynamic properties and to
compare these properties to those obtained from CPMD and a MD simulation using
the so-called BKS potential. The new potential reproduces accurately the liquid
structure generated by the CPMD trajectories, the experimental activation
energies for the self-diffusion constants and the experimental density of
amorphous silica. Also lattice parameters and elastic constants of alpha-quartz
are well-reproduced, showing the transferability of the new potential.
| v1 (Mon, 18 Feb 2008 18:54:33 GMT) |
802.2422 | Nobusuke Takahashi | N.Takahashi, E.Konishi and A.Misaki | Takahashi N., Konishi E., Misaki A. | The numerical computer experiment for the neutrino events with the SK
neutrino oscillation parameters occurring outside the Superkamiokande
detector | 21 pages, 31 figures | null | null | hep-ph hep-ex | Adopting neutrino oscillation parameters obtained by Super-Kamiokande, a
numerical computer experiment for neutrino events occurring outside the
detector, is carried out in the same SK live days, 1645.9 live days,
constructing the virtual Super-Kamiokande detector in the computer. The
numerical results by the computer experiment could be directly compared with
the real SK experimental data. The comparison shows that it is difficult to
obtain convincing conclusion on the existence of the neutrino oscillation with
specified neutrino oscillation parameters claimed by SK through analysis for
neutrino events occurring outside the detector.
| v1 (Mon, 18 Feb 2008 06:47:13 GMT) |
802.2423 | Ying Liu | Y. Liu, J. G. Luhmann, R. M\"uller-Mellin, P. C. Schroeder, L. Wang,
R. P. Lin, S. D. Bale, Y. Li, M. H. Acu\~na, and J.-A. Sauvaud | Liu Y., Luhmann J. G., Müller-Mellin R., Schroeder P. C., Wang L., Lin R. P., Bale S. D., Li Y., Acuña M. H., Sauvaud J. -A. | A Comprehensive View of the 2006 December 13 CME: From the Sun to
Interplanetary Space | 26 pages, 10 figures. 2008, ApJ, in press | null | 10.1086/592031 | astro-ph | The biggest halo coronal mass ejection (CME) since the Halloween storm in
2003, which occurred on 2006 December 13, is studied in terms of its solar
source and heliospheric consequences. The CME is accompanied by an X3.4 flare,
EUV dimmings and coronal waves. It generated significant space weather effects
such as an interplanetary shock, radio bursts, major solar energetic particle
(SEP) events, and a magnetic cloud (MC) detected by a fleet of spacecraft
including STEREO, ACE, Wind and Ulysses. Reconstruction of the MC with the
Grad-Shafranov (GS) method yields an axis orientation oblique to the flare
ribbons. Observations of the SEP intensities and anisotropies show that the
particles can be trapped, deflected and reaccelerated by the large-scale
transient structures. The CME-driven shock is observed at both the Earth and
Ulysses when they are separated by 74$^{\circ}$ in latitude and 117$^{\circ}$
in longitude, the largest shock extent ever detected. The ejecta seems missed
at Ulysses. The shock arrival time at Ulysses is well predicted by an MHD model
which can propagate the 1 AU data outward. The CME/shock is tracked remarkably
well from the Sun all the way to Ulysses by coronagraph images, type II
frequency drift, in situ measurements and the MHD model. These results reveal a
technique which combines MHD propagation of the solar wind and type II
emissions to predict the shock arrival time at the Earth, a significant advance
for space weather forecasting especially when in situ data are available from
the Solar Orbiter and Sentinels.
| v1 (Mon, 18 Feb 2008 07:06:02 GMT), v2 (Thu, 21 Feb 2008 01:55:00 GMT), v3 (Fri, 18 Jul 2008 00:31:18 GMT) |
802.2424 | Erwan Le Pennec | Florent Autin (MODAL'X), Erwan Le Pennec (PMA), Karine Tribouley
(MODAL'X, PMA) | Autin Florent, Pennec Erwan Le, Tribouley Karine | Thresholding methods to estimate the copula density | null | Journal of Multivariate Analysis 101, 1 (2010) 200-222 | 10.1016/j.jmva.2009.07.009 | math.ST stat.TH | This paper deals with the problem of the multivariate copula density
estimation. Using wavelet methods we provide two shrinkage procedures based on
thresholding rules for which the knowledge of the regularity of the copula
density to be estimated is not necessary. These methods, said to be adaptive,
are proved to perform very well when adopting the minimax and the maxiset
approaches. Moreover we show that these procedures can be discriminated in the
maxiset sense. We produce an estimation algorithm whose qualities are evaluated
thanks some simulation. Last, we propose a real life application for financial
data.
| v1 (Mon, 18 Feb 2008 07:15:12 GMT) |
802.2425 | Yoshihiro Kuge | Yoshihiro Kuge, Isao Maruyama and Yasuhiro Hatsugai | Kuge Yoshihiro, Maruyama Isao, Hatsugai Yasuhiro | Topological Aspects of Surface States in Semiconductors | 10 pages, 9 figures; two-column | null | null | cond-mat.str-el cond-mat.mes-hall | Topological aspects of surface states in semiconductors are studied by an
adiabatic deformation which connects a realistic system and a decoupled
covalent-bond model. Two topological invariants are focused. One is a quantized
Berry phase, and the other is a number of the edge states. A winding number as
another topological invariant is also considered. The surface states of Si and
Ge at (111), (110), and (100) surfaces are classified by the topological
invariants. Surface states of the GaAs as heterosemiconductors are also
discussed.
| v1 (Mon, 18 Feb 2008 07:18:25 GMT), v2 (Tue, 19 Feb 2008 07:32:24 GMT) |
802.2426 | Bertrand Iooss | Claire Cannamela, Josselin Garnier, Bertrand Iooss | Cannamela Claire, Garnier Josselin, Iooss Bertrand | Controlled stratification for quantile estimation | Published in at http://dx.doi.org/10.1214/08-AOAS186 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org) | Annals of Applied Statistics 2008, Vol. 2, No. 4, 1554-1580 | 10.1214/08-AOAS186 | stat.ME math.ST stat.AP stat.TH | In this paper we propose and discuss variance reduction techniques for the
estimation of quantiles of the output of a complex model with random input
parameters. These techniques are based on the use of a reduced model, such as a
metamodel or a response surface. The reduced model can be used as a control
variate; or a rejection method can be implemented to sample the realizations of
the input parameters in prescribed relevant strata; or the reduced model can be
used to determine a good biased distribution of the input parameters for the
implementation of an importance sampling strategy. The different strategies are
analyzed and the asymptotic variances are computed, which shows the benefit of
an adaptive controlled stratification method. This method is finally applied to
a real example (computation of the peak cladding temperature during a
large-break loss of coolant accident in a nuclear reactor).
| v1 (Mon, 18 Feb 2008 07:19:52 GMT), v2 (Tue, 27 Jan 2009 12:56:56 GMT) |
802.2427 | Herve Courtois | Sukumar Rajauria (NEEL), Philippe Gandit (NEEL), Thierry Fournier
(NEEL), F. W. J. Hekking (PMMC), Bernard Pannetier (NEEL), Herv\'e Courtois
(NEEL) | Rajauria Sukumar, Gandit Philippe, Fournier Thierry, Hekking F. W. J., Pannetier Bernard, Courtois Hervé | Andreev Current-Induced Dissipation in a Hybrid Superconducting Tunnel
Junction | null | Physical Review Letters 100 (2008) 207002 | 10.1103/PhysRevLett.100.207002 | cond-mat.supr-con | We have studied hybrid superconducting micro-coolers made of a double
Superconductor-Insulator-Normal metal tunnel junction. Under subgap conditions,
the Andreev current is found to dominate the single-particle tunnel current. We
show that the Andreev current introduces additional dissipation in the normal
metal equivalent to Joule heating. By analyzing quantitatively the heat balance
in the system, we provide a full description of the evolution of the electronic
temperature with the voltage. The dissipation induced by the Andreev current is
found to dominate the quasiparticle tunneling-based cooling over a large bias
range.
| v1 (Mon, 18 Feb 2008 07:25:21 GMT), v2 (Tue, 3 Jun 2008 08:26:59 GMT) |
802.2428 | Alexandre Benoit | Oya Aran, Ismail Ari, Alexandre Benoit (GIPSA-lab), Ana Huerta
Carrillo, Fran\c{c}ois-Xavier Fanard (TELE), Pavel Campr, Lale Akarun, Alice
Caplier (GIPSA-lab), Michele Rombaut (GIPSA-lab), Bulent Sankur | Aran Oya, Ari Ismail, Benoit Alexandre, Carrillo Ana Huerta, Fanard François-Xavier, Campr Pavel, Akarun Lale, Caplier Alice, Rombaut Michele, Sankur Bulent | Sign Language Tutoring Tool | eNTERFACE'06. Summer Workshop. on Multimodal Interfaces, Dubrovnik :
Croatie (2007) | null | null | cs.LG cs.HC | In this project, we have developed a sign language tutor that lets users
learn isolated signs by watching recorded videos and by trying the same signs.
The system records the user's video and analyses it. If the sign is recognized,
both verbal and animated feedback is given to the user. The system is able to
recognize complex signs that involve both hand gestures and head movements and
expressions. Our performance tests yield a 99% recognition rate on signs
involving only manual gestures and 85% recognition rate on signs that involve
both manual and non manual components, such as head movement and facial
expressions.
| v1 (Mon, 18 Feb 2008 07:28:44 GMT) |
802.2429 | Sebastien Verel | David Simoncini (I3S), S\'ebastien Verel (I3S), Philippe Collard
(I3S), Manuel Clergue (I3S) | Simoncini David, Verel Sébastien, Collard Philippe, Clergue Manuel | Anisotropic selection in cellular genetic algorithms | null | Dans Proceedings of the 8th annual conference on Genetic and
evolutionary computation - Genetic And Evolutionary Computation Conference,
Seatle : \'Etats-Unis d'Am\'erique (2006) | 10.1145/1143997.1144098 | cs.AI | In this paper we introduce a new selection scheme in cellular genetic
algorithms (cGAs). Anisotropic Selection (AS) promotes diversity and allows
accurate control of the selective pressure. First we compare this new scheme
with the classical rectangular grid shapes solution according to the selective
pressure: we can obtain the same takeover time with the two techniques although
the spreading of the best individual is different. We then give experimental
results that show to what extent AS promotes the emergence of niches that
support low coupling and high cohesion. Finally, using a cGA with anisotropic
selection on a Quadratic Assignment Problem we show the existence of an
anisotropic optimal value for which the best average performance is observed.
Further work will focus on the selective pressure self-adjustment ability
provided by this new selection scheme.
| v1 (Mon, 18 Feb 2008 07:30:04 GMT) |
802.243 | Phil Yoon PhD | Phil S. Yoon, David E. Johnson, and Weiren Chou | Yoon Phil S., Johnson David E., Chou Weiren | The Modeling of Time-Structured Multiturn Injection into Fermilab Main
Injector (Microbunch Injection with Parasitic Longitudinal Painting) | 42 pages, 35 figures | null | null | physics.acc-ph physics.comp-ph | This paper presents the modeling of time-structured multiturn injection for
an upgraded Main Injector with the 8-GeV Superconducting RF proton driver, or
an ILC-style linac, or a Project-X linac. The Radio-Frequency mismatch between
a linac and the upgraded Main Injector will induce parasitic longitudinal
painting in RF-phase direction. Several different scenarios with a choice of
different RF parameters for single RF system and double RF system in the
presence of longitudinal space charge have been investigated. From the studies
of microbunch injection with the aid of ESME (2003) numerical simulations, it
is found that the dual RF system with a choice of appropriate RF parameters
allows us to overcome the space-charge limitation set by beam intensity during
the multiturn-injection process. A double RF system with a harmonic ratio (R_H
= H_2/H_1) of 2.0 and a voltage ratio (R_V = V_2/V_1) of 0.5 are most favored
to reduce both longitudinal and transverse effects of space charge in the Main
Injector.
| v1 (Mon, 18 Feb 2008 07:39:38 GMT), v2 (Sun, 5 Aug 2012 08:57:41 GMT) |
802.2431 | Zurab Silagadze | O.I. Chashchina, Z.K. Silagadze | Chashchina O. I., Silagadze Z. K. | Remark on orbital precession due to central-force perturbations | 3 pages, ReVTeX4, title changed to match the version to be published
in Phys. Rev. D, one new reference added, minor corrections in the text | Phys.Rev.D77:107502,2008 | 10.1103/PhysRevD.77.107502 | gr-qc | This is a comment on the recent paper by G. S. Adkins and J. McDonnell
``Orbital precession due to central-force perturbations'' published in Phys.
Rev. D75 (2007), 082001 [arXiv:gr-qc/0702015]. We show that the main result of
this paper, the formula for the precession of Keplerian orbits induced by
central-force perturbations, can be obtained very simply by the use of
Hamilton's vector.
| v1 (Mon, 18 Feb 2008 10:19:22 GMT), v2 (Mon, 31 Mar 2008 04:58:32 GMT) |
802.2432 | Andrei Romashchenko | Bruno Durand (LIF), Andrei Romashchenko (LIP), Alexander Shen (LIF) | Durand Bruno, Romashchenko Andrei, Shen Alexander | Fixed Point and Aperiodic Tilings | v5: technical revision (positions of figures are shifted) | 12th International Conference on Developments in Language Theory,
Kyoto : Japan (2008) | 10.1007/978-3-540-85780-8_22 | cs.CC cs.DM | An aperiodic tile set was first constructed by R.Berger while proving the
undecidability of the domino problem. It turned out that aperiodic tile sets
appear in many topics ranging from logic (the Entscheidungsproblem) to physics
(quasicrystals) We present a new construction of an aperiodic tile set that is
based on Kleene's fixed-point construction instead of geometric arguments. This
construction is similar to J. von Neumann self-reproducing automata; similar
ideas were also used by P. Gacs in the context of error-correcting
computations. The flexibility of this construction allows us to construct a
"robust" aperiodic tile set that does not have periodic (or close to periodic)
tilings even if we allow some (sparse enough) tiling errors. This property was
not known for any of the existing aperiodic tile sets.
| v1 (Mon, 18 Feb 2008 07:50:13 GMT), v2 (Tue, 19 Feb 2008 15:43:21 GMT), v3 (Mon, 7 Jul 2008 11:16:24 GMT), v4 (Wed, 13 Jan 2010 13:50:04 GMT), v5 (Wed, 27 Jan 2010 14:15:07 GMT) |
802.2433 | Agam Jha | R. Ramanathan, Agam k. Jha, K. k. Gupta and S. S. Singh (University of
Delhi, Delhi) | Ramanathan R., Jha Agam k., Gupta K. k., Singh S. S. | Effect of finite chemical potential on QGP-Hadron phase transition in a
statistical model of fireball formation | LaTex 20 pages, 20 figures | Indian J.Phys.85:885-889,2011 | 10.1007/s12648-011-0094-7 | hep-ph | We study the effect of finite chemical potential for the QGP constituents in
the Ramanathan et al. statistical model (Phys.Rev.C70, 027903,2004). While the
earlier computations using this model with vanishing chemical potentials
indicated a weakly first order phase transition for the system in the vicinity
of 170 MeV (Pramana, 68, 757, 2007), the introduction of finite values for the
chemical potentials of the constituents makes the transition a smooth roll over
of the phases, while allowing fireball formation with radius of a few "fermi"
to take place. This seems to be in conformity with the latest consensus on the
nature of the QGP-Hadron phase transition.
Keywords: Quark Gluon Plasma, Quark Hadron Phase Transition
| v1 (Mon, 18 Feb 2008 07:54:18 GMT) |
802.2434 | Mykola Shpot | M. A. Shpot, H. W. Diehl, and Yu. M. Pis'mak | Shpot M. A., Diehl H. W., Pis'mak Yu. M. | Compatibility of 1/n and epsilon expansions for critical exponents at
m-axial Lifshitz points | 8 pages, submitted to J. Phys. A | J. Phys. A: Math. Theor. 41, 135003 (2008) | 10.1088/1751-8113/41/13/135003 | cond-mat.stat-mech hep-th | The critical behaviour of d-dimensional n-vector models at m-axial Lifshitz
points is considered for general values of m in the large-n limit. It is proven
that the recently obtained large-N expansions [J. Phys.: Condens. Matter 17,
S1947 (2005)] of the correlation exponents \eta_{L2}, \eta_{L4} and the related
anisotropy exponent \theta are fully consistent with the dimensionality
expansions to second order in \epsilon=4+m/2-d [Phys. Rev. B 62, 12338 (2000);
Nucl. Phys. B 612, 340 (2001)] inasmuch as both expansions yield the same
contributions of order \epsilon^2/n.
| v1 (Mon, 18 Feb 2008 08:28:13 GMT) |
802.2435 | Victor Mironov | Victor L. Mironov, Sergey V. Mironov | Mironov Victor L., Mironov Sergey V. | Octonic Electrodynamics | 12 pages, 1 figure | Journal of Mathematical Physics, 50, 012901 (2009) | 10.1063/1.3041499 | math-ph math.MP | In this paper we present eight-component values "octons", generating
associative noncommutative algebra. It is shown that the electromagnetic field
in a vacuum can be described by a generalized octonic equation, which leads
both to the wave equations for potentials and fields and to the system of
Maxwell's equations. The octonic algebra allows one to perform compact combined
calculations simultaneously with scalars, vectors, pseudoscalars and
pseudovectors. Examples of such calculations are demonstrated by deriving the
relations for energy, momentum and Lorentz invariants of the electromagnetic
field. The generalized octonic equation for electromagnetic field in a matter
is formulated.
| v1 (Mon, 18 Feb 2008 08:31:12 GMT), v2 (Thu, 26 Jun 2014 08:05:37 GMT) |
802.2436 | Stefan Schulz | S. Schulz, S. Schumacher, G. Czycholl | Schulz S., Schumacher S., Czycholl G. | Spin-orbit coupling and crystal-field splitting in the electronic and
optical properties of nitride quantum dots with a wurtzite crystal structure | 9 pages, 6 figures | null | 10.1140/epjb/e2008-00269-7 | cond-mat.mtrl-sci | We present an $sp^3$ tight-binding model for the calculation of the
electronic and optical properties of wurtzite semiconductor quantum dots (QDs).
The tight-binding model takes into account strain, piezoelectricity, spin-orbit
coupling and crystal-field splitting. Excitonic absorption spectra are
calculated using the configuration interaction scheme. We study the electronic
and optical properties of InN/GaN QDs and their dependence on structural
properties, crystal-field splitting, and spin-orbit coupling.
| v1 (Mon, 18 Feb 2008 08:36:54 GMT) |
802.2437 | Mohsen Nejad-Asghar | M. Nejad-Asghar and D. Molteni | Nejad-Asghar M., Molteni D. | Modeling fragmentation of the self-gravitating molecular layer by
smoothed particle hydrodynamics | to appear in proceeding of The JENAM 2007, August 20-25, Yerevan,
Armenia | null | null | astro-ph | We revisit the modeling of ion-neutral (or ambipolar) diffusion with two
fluid smoothed particle hydrodynamics, as discussed by Hosking & Whitworth.
Some parts of the technique are optimized to testify the pioneer works on
behavior of the ambipolar diffusion in an isothermal self-gravitating layer.
The frictional heating by ambipolar diffusion is examined, and its effect on
fragmentation of the layer is studied. The results are compared to the thermal
phases of instability as obtained by Nejad-Asghar.
| v1 (Mon, 18 Feb 2008 08:47:34 GMT), v2 (Sun, 13 Apr 2008 04:43:31 GMT) |
802.2438 | Ion Dinca Mr | Ion I. Dinca | Dinca Ion I. | Peterson's Deformations of Higher Dimensional Quadrics | null | SIGMA 6 (2010), 006, 13 pages | 10.3842/SIGMA.2010.006 | math.DG | We provide the first explicit examples of deformations of higher dimensional
quadrics: a straightforward generalization of Peterson's explicit 1-dimensional
family of deformations in $\mathbb{C}^3$ of 2-dimensional general quadrics with
common conjugate system given by the spherical coordinates on the complex
sphere $\mathbb{S}^2\subset\mathbb{C}^3$ to an explicit $(n-1)$-dimensional
family of deformations in $\mathbb{C}^{2n-1}$ of $n$-dimensional general
quadrics with common conjugate system given by the spherical coordinates on the
complex sphere $\mathbb{S}^n\subset\mathbb{C}^{n+1}$ and non-degenerate joined
second fundamental forms. It is then proven that this family is maximal.
| v1 (Mon, 18 Feb 2008 08:56:14 GMT), v2 (Tue, 19 Feb 2008 06:20:49 GMT), v3 (Tue, 18 Mar 2008 09:35:40 GMT), v4 (Wed, 2 Apr 2008 06:10:45 GMT), v5 (Sat, 5 Apr 2008 06:22:00 GMT), v6 (Sun, 13 Apr 2008 10:48:36 GMT), v7 (Tue, 15 Apr 2008 11:41:28 GMT), v8 (Wed, 20 Jan 2010 07:20:06 GMT) |
802.2439 | Vinod Kumar | Vinod Kumar P.B., K. Babu Joseph | B. Vinod Kumar P., Joseph K. Babu | Fermats Last Theorem on Topological Fields | 13 pages | null | null | math.GM | Even though flt is a number theoretic result we prove that the result depends
on the topological as well as the field structure of the underlying space.
| v1 (Mon, 18 Feb 2008 09:10:20 GMT) |
802.244 | Nivedita Deo | Itty Garg and N. Deo | Garg Itty, Deo N. | Genus Distributions For Extended Matrix Models Of RNA | 15 pages, 4 figures, 3 tables | null | null | cond-mat.stat-mech cond-mat.soft q-bio.BM | We construct and study an extended random matrix model of RNA (polymer)
folding. A perturbation which acts on all the nucleotides in the chain is added
to the action of the RNA partition function. The effect of this perturbation on
the partition function and the Genus Distributions is studied. This
perturbation distinguishes between the paired and unpaired bases. For example,
for $\alpha = 1$ (where $\alpha$ is the ratio of the strengths of the original
and perturbed term in the action) the partition function and genus distribution
for odd lengths vanish completely. This partition function and the genus
distribution is non-zero for even lengths where structures with fully paired
bases only remain. This implies that (i). the genus distributions are different
and (ii). there is a ``structural transition'' (from an ``unpaired-paired base
phase'' to a ``completely paired base phase'') as $\alpha$ approaches 1 in the
extended matrix models. We compare the results of the extended RNA model with
the results of G. Vernizzi, H. Orland and A. Zee in PRL 94, 168103(2005).
| v1 (Mon, 18 Feb 2008 09:23:07 GMT), v2 (Wed, 23 Apr 2008 12:44:08 GMT) |
802.2441 | Adrien Dubouloz | Adrien Dubouloz (IMB), St\'ephane Lamy (ICJ) | Dubouloz Adrien, Lamy Stéphane | Variations on Log Sarkisov Program for Surfaces | Revised and enlarged version with new examples and applications | null | null | math.AG | Let (S, BS) be the log-pair associated with a compactification of a given
smooth quasi-projective surface V . Under the assumption that the boundary BS
is irreducible, we propose an algorithm, in the spirit of the (log) Sarkisov
program, to factorize any automorphism of V into a sequence of elementary links
in the framework of the logarithmic Mori theory. The new noteworthy feature of
our algorithm is that all the blow-ups and contractions involved in the process
occur on the boundary.
| v1 (Mon, 18 Feb 2008 09:26:16 GMT), v2 (Wed, 11 Feb 2009 15:34:49 GMT) |
802.2442 | Nils Paar Dr. | T. Niksic, D. Vretenar, G. A. Lalazissis, and P. Ring | Niksic T., Vretenar D., Lalazissis G. A., Ring P. | Finite- to zero-range relativistic mean-field interactions | 25 pages, 5 figures, accepted for publication in Physical Review C | Phys.Rev.C77:034302,2008 | 10.1103/PhysRevC.77.034302 | nucl-th | We study the relation between the finite-range (meson-exchange) and
zero-range (point-coupling) representations of effective nuclear interactions
in the relativistic mean-field framework. Starting from the phenomenological
interaction DD-ME2 with density-dependent meson-nucleon couplings, we construct
a family of point-coupling effective interactions for different values of the
strength parameter of the isoscalar-scalar derivative term. In the
meson-exchange picture this corresponds to different values of the
$\sigma$-meson mass. The parameters of the isoscalar-scalar and
isovector-vector channels of the point-coupling interactions are adjusted to
nuclear matter and ground-state properties of finite nuclei. By comparing
results for infinite and semi-infinite nuclear matter, ground-state masses,
charge radii, and collective excitations, we discuss constraints on the
parameters of phenomenological point-coupling relativistic effective
interaction.
| v1 (Mon, 18 Feb 2008 09:41:23 GMT), v2 (Thu, 6 Mar 2008 16:10:00 GMT) |
802.2443 | John V. Corbett | John V. Corbett and Dipankar Home | Corbett John V., Home Dipankar | Bell's Inequality, Quantum Measurement and Einstein Realism: A Unified
Perspective | 15 pages | null | null | quant-ph | The logical foundations of Bell's inequality are reexamined. We argue that
the form of the reality condition that underpins Bell's inequality comes from
the requirement of solving the quantum measurement problem. Hence any violation
of Bell's inequality necessarily implies nonlocality because of the measurement
problem. The differences in the implications of deterministic and stochastic
formulations of Bell's inequality are highlighted. The reality condition used
in Bell's inequality is shown to be a generalisation of Einstein's later form
of realism.
| v1 (Mon, 18 Feb 2008 09:48:49 GMT) |
802.2444 | Paul Walmsley | P. M. Walmsley and A. I. Golov | Walmsley P. M., Golov A. I. | Quantum and quasiclassical types of superfluid turbulence | Final version. 4 pages, 5 figures | Phys. Rev. Lett. 100, 245301 (2008) | 10.1103/PhysRevLett.100.245301 | cond-mat.other | By injecting negative ions in superfluid 4He in the zero-temperature limit (T
< 0.5 K), we generated tangles of quantized vortex line with negligible
large-scale flow. For this quantum regime of superfluid turbulence, the vortex
line length L was found to decay at late time t as L proportional to t^{-1};
the prefactor being independent of the initial value of L. The corresponding
effective kinematic viscosity is 0.1 kappa, where kappa is the circulation
quantum. At T > 0.7 K, a jet of ions generates quasi-classical tangles
identical to those produced by mechanical means.
| v1 (Mon, 18 Feb 2008 12:57:34 GMT), v2 (Wed, 1 Oct 2008 08:47:49 GMT) |
802.2445 | Kuo-Chang Chen | Kuo-Chang Chen and Xun Dong | Chen Kuo-Chang, Dong Xun | On the mass center of the tent map | 15 pages | null | null | math.DS | It is well known that the time average or the center of mass for generic
orbits of the standard tent map is 0.5. In this paper we show some interesting
properties of the exceptional orbits, including periodic orbits, orbits without
mass center, and orbits with mass centers different from 0.5. We prove that for
any positive integer $n$, there exist $n$ distinct periodic orbits for the
standard tent map with the same center of mass, and the set of mass centers of
periodic orbits is a dense subset of $[0,2/3]$. Considering all possible
orbits, then the set of mass centers is the interval $[0,2/3]$. Moreover, for
every $x$ in $[0,2/3]$, there are uncountably many orbits with mass center $x$.
We also show that there are uncountably many orbits without mass center.
| v1 (Mon, 18 Feb 2008 10:00:00 GMT) |
802.2446 | Sambaran Banerjee Mr. | Sambaran Banerjee and Pranab Ghosh | Banerjee Sambaran, Ghosh Pranab | Evolution of Compact-Binary Populations in Globular Clusters: A
Boltzmann Study II. Introducing Stochasticity | 32 pages, 8 figures. To be published in the Astrophysical Journal,
Vol. 680, No.1, June 10, 2008. Minor revision in abstract | null | 10.1086/587677 | astro-ph | We continue exploration of the Boltzmann scheme started in Banerjee and Ghosh
(2007, henceforth Paper I) for studying the evolution of compact-binary
populations of globular clusters, introducing in this paper our method of
handling the stochasticity inherent in dynamical processes of binary formation,
destruction and hardening in globular clusters. We describe these stochastic
processes as "Wiener processes", whereupon the Boltzmann equation becomes a
stochastic partial differential equation, the solution of which requires the
use of "Ito calculus" (this use being the first, to our knowledge, in this
subject), in addition to ordinary calculus. We focus on the evolution of (a)
the number of X-ray binaries $N_{XB}$ in globular clusters, and (b) the
orbital-period distribution of these binaries. We show that, although the
details of the fluctuations in the above quantities differ from one
"realization" to another of the stochastic processes, the general trends follow
those found in the continuous-limit study of Paper I, and the average result
over many such realizations is close to the continuous-limit result. We
investigate the dependence of $N_{XB}$ found by these calculations on two
essential globular-cluster parameters, namely, the star-star and star-binary
encounter-rate parameters $\Gamma$ and $\gamma$, for which we had coined the
name Verbunt parameters in Paper I. We compare our computed results with those
from CHANDRA observations of Galactic globular clusters, showing that the
expected scalings of $N_{XB}$ with the Verbunt parameters are in good agreement
with the observed ones. We indicate what additional features can be
incorporated into the scheme in future, and how more elaborate problems can be
tackled.
| v1 (Mon, 18 Feb 2008 10:04:06 GMT), v2 (Wed, 20 Feb 2008 08:57:26 GMT), v3 (Mon, 14 Apr 2008 19:41:22 GMT) |
802.2447 | Ugo Moschella | Ugo Moschella, Richard Schaeffer | Moschella Ugo, Schaeffer Richard | A note on canonical quantization of fields on a manifold | null | JCAP 0902:033,2009 | 10.1088/1475-7516/2009/02/033 | gr-qc hep-th | We propose a general construction of quantum states for linear canonical
quantum fields on a manifold, which encompasses and generalizes the "standard"
procedures existing in textbooks. Our method provides pure and mixed states on
the same footing. A large class of examples finds a simple and unified
treatment in our approach. Applications discussed here include thermodynamical
equilibrium states for Minkowski fields and quantum field theory in the
Rindler's and in the open de Sitter universes. Our approach puts the above
examples into perspective and unravels new possibilities for quantization. We
call our generalization "extended canonical quantization" as it is suited to
attack cases not directly covered by the standard canonical approach.
| v1 (Mon, 18 Feb 2008 13:32:42 GMT), v2 (Wed, 1 Apr 2009 14:17:15 GMT) |
802.2448 | Jonathan Silman | Y. Strauss, J. Silman, S. Machnes, L.P. Horwitz | Strauss Y., Silman J., Machnes S., Horwitz L. P. | An Arrow of Time Operator for Standard Quantum Mechanics | 5 pages, 2 figures | null | null | quant-ph | We introduce a self-adjoint operator that indicates the direction of time
within the framework of standard quantum mechanics. That is, as a function of
time its expectation value decreases monotonically for any initial state. This
operator can be defined for any system governed by a Hamiltonian with a
uniformly finitely degenerate, absolutely continuous and semibounded spectrum.
We study some of the operator's properties and illustrate them for a large
equivalence class of scattering problems. We also discuss some previous
attempts to construct such an operator, and show that the no-go theorems
developed in this context are not applicable to our construction.
| v1 (Mon, 18 Feb 2008 10:11:00 GMT) |
802.2449 | Bin Wang | Xi He, Songbai-Chen, Bin Wang, Rong-Gen Cai and Chi-Yong Lin | He Xi, Songbai-Chen , Wang Bin, Cai Rong-Gen, Lin Chi-Yong | Quasinormal modes in the background of charged Kaluza-Klein black hole
with squashed horizons | revised version, accepted for publication in Phys.Lett.B | Phys.Lett.B665:392-400,2008 | 10.1016/j.physletb.2008.06.038 | hep-th gr-qc | We study the scalar perturbation in the background of the charged
Kaluza-Klein black holes with squashed horizons. We find that the position of
infinite discontinuities of the heat capacities can be reflected in quasinormal
spectrum. This shows the possible non-trivial relation between the
thermodynamical and dynamical properties of black holes.
| v1 (Mon, 18 Feb 2008 10:24:09 GMT), v2 (Tue, 17 Jun 2008 11:54:45 GMT) |
802.245 | Z. Ya. Turakulov | A.T. Muminov | Muminov A. T. | Motion of Spin 1/2 Massless Particle in a Curved Spacetime. I.
Lagrangian Approach | 7 pages | null | null | gr-qc | Quasi-classical picture of motion of spin 1/2 massless particle in a curved
spacetime is built on base of simple Lagrangian model. The one is constructed
due to analogy with Lagrangian of massive spin 1/2 particle. Equations of
motion and spin propagation coincide with Papapetrou equations describing
dynamic of photon in a curved spacetime.
| v1 (Mon, 18 Feb 2008 10:31:45 GMT) |
802.2451 | Georg Bocherer | Georg Bocherer and Valdemar Cardoso da Rocha Junior and Cecilio
Pimentel | Bocherer Georg, Junior Valdemar Cardoso da Rocha, Pimentel Cecilio | Capacity of General Discrete Noiseless Channels | 4 pages. Essentially the paper that appeared in Proc. ISCTA '07,
2007. From v1 to v2, one error was corrected | null | null | cs.IT math.IT | This paper concerns the capacity of the discrete noiseless channel introduced
by Shannon. A sufficient condition is given for the capacity to be
well-defined. For a general discrete noiseless channel allowing non-integer
valued symbol weights, it is shown that the capacity--if well-defined--can be
determined from the radius of convergence of its generating function, from the
smallest positive pole of its generating function, or from the rightmost real
singularity of its complex generating function. A generalisation is given for
Pringsheim's Theorem and for the Exponential Growth Formula to generating
functions of combinatorial structures with non-integer valued symbol weights.
| v1 (Mon, 18 Feb 2008 11:06:47 GMT), v2 (Thu, 10 Jun 2010 11:08:11 GMT) |
802.2452 | Jun'ichi Yokoyama | Kazunori Nakayama, Shun Saito, Yudai Suwa, and Jun'ichi Yokoyama | Nakayama Kazunori, Saito Shun, Suwa Yudai, Yokoyama Jun'ichi | Space laser interferometers can determine the thermal history of the
early Universe | 5 pages | Phys.Rev.D77:124001,2008 | 10.1103/PhysRevD.77.124001 | hep-ph | It is shown that space-based gravitational wave detectors such as DECIGO
and/or Big Bang Observer (BBO) will provide us with invaluable information on
the cosmic thermal history after inflation and they will be able to determine
the reheat temperature $T_R$ provided that it lies in the range preferred by
the cosmological gravitino problem, $T_R\sim 10^{5-9}$ GeV. Therefore it is
strongly desired that they will be put into practice as soon as possible.
| v1 (Mon, 18 Feb 2008 11:59:24 GMT) |
802.2453 | Steven Thomas | Vincenzo Cal\`o and Steven Thomas | Calò Vincenzo, Thomas Steven | Phase Transitions in Separated $D_{p-1}$ and anti-$D_{p-1}$ Branes at
Finite Temperature | 25 pages, 4 figures; Clarifications added to Section 3 concerning
winding modes; updated plots of the effective potential in section 4; typos
corrected. Version to be published in JHEP | JHEP 0806:093,2008 | 10.1088/1126-6708/2008/06/093 | hep-th | We consider a pair of parallel ${\rm D}_{p-1}$ and anti-${\rm D}_{p-1}$
branes in flat space, with a finite separation $d$ along some perpendicular
spatial direction and at finite temperature. If this spatial direction is
compactified on a circle then by T-duality, the system is equivalent to a ${\rm
D}_{p}$-anti ${\rm D}_{p} $ pair wrapped around the dual circle with a constant
Wilson line $A \approx d $ on one of the branes. We focus in particular on the
$p=9$ case and compute the free energy of this system and study the occurrence
of second order phase transitions as both the temperature and Wilson line
(brane-antibrane separation) are varied. In the limit of vanishing Wilson line
we recover the previous results obtained in the literature, whereby the open
string vacuum at the origin of the tachyon field T=0 is stabilized at
sufficiently high temperature at which a second order phase transition occurs.
For sufficiently large Wilson line, we find new second order phase transitions
corresponding to the existence of two minima in the tachyon effective potential
at finite temperature and tachyon field value. Entropic arguments suggest that
as the system cools, the tachyon is likely to find itself in the minimum that
approaches infinity as the temperature vanishes (i.e. the one corresponding to
the closed string vacuum), rather than the minimum at T=0 (corresponding to the
open string vacuum).
| v1 (Mon, 18 Feb 2008 10:41:35 GMT), v2 (Wed, 18 Jun 2008 15:12:52 GMT) |
802.2454 | Wlodzimierz Jelonek | Wlodzimierz Jelonek | Jelonek Wlodzimierz | On A-tensors in Riemannian geometry | 12 pages, preprint PAN 551,1995 | null | null | math.DG | We present examples, both compact and non-compact complete, of lo- cally
non-homogeneous proper A-manifolds.
| v1 (Mon, 18 Feb 2008 11:03:24 GMT) |
802.2455 | Frank Kr\"uger | J. Zaanen, F. Kr\"uger, J.-H. She, D. Sadri, S. I. Mukhin | Zaanen J., Krüger F., She J. -H., Sadri D., Mukhin S. I. | Pacifying the Fermi-liquid: battling the devious fermion signs | 28 pages, 5 figures | null | null | cond-mat.other | The fermion sign problem is studied in the path integral formalism. The
standard picture of Fermi liquids is first critically analyzed, pointing out
some of its rather peculiar properties. The insightful work of Ceperley in
constructing fermionic path integrals in terms of constrained world-lines is
then reviewed. In this representation, the minus signs associated with
Fermi-Dirac statistics are self consistently translated into a geometrical
constraint structure (the {\em nodal hypersurface}) acting on an effective
bosonic dynamics. As an illustrative example we use this formalism to study
1+1-dimensional systems, where statistics are irrelevant, and hence the sign
problem can be circumvented. In this low-dimensional example, the structure of
the nodal constraints leads to a lucid picture of the entropic interaction
essential to one-dimensional physics. Working with the path integral in
momentum space, we then show that the Fermi gas can be understood by analogy to
a Mott insulator in a harmonic trap. Going back to real space, we discuss the
topological properties of the nodal cells, and suggest a new holographic
conjecture relating Fermi liquids in higher dimensions to soft-core bosons in
one dimension. We also discuss some possible connections between mixed
Bose/Fermi systems and supersymmetry.
| v1 (Mon, 18 Feb 2008 11:09:46 GMT) |
802.2456 | Shailesh Kulkarni | Shailesh Kulkarni | Kulkarni Shailesh | Hawking Fluxes, Back reaction and Covariant Anomalies | 6 pages, no figures, minor changes and references added, to appear in
Classical and Quantum Gravity | Class.Quant.Grav.25:225023,2008 | 10.1088/0264-9381/25/22/225023 | hep-th | Starting from the chiral covariant effective action approach of Banerjee and
Kulkarni [Phys. Lett. B 659, 827(2008)], we provide a derivation of the Hawking
radiation from a charged black hole in the presence of gravitational back
reaction. The modified expressions for charge and energy flux, due to effect of
one loop back reaction are obtained.
| v1 (Mon, 18 Feb 2008 11:09:49 GMT), v2 (Tue, 16 Sep 2008 17:13:43 GMT) |
802.2457 | Shachar Klaiman | Shachar Klaiman, Nimrod Moiseyev, and Uwe Gunther | Klaiman Shachar, Moiseyev Nimrod, Gunther Uwe | Visualization of Branch Points in PT-Symmetric Waveguides | null | Phys.Rev.Lett.101:080402,2008 | 10.1103/PhysRevLett.101.080402 | quant-ph | The visualization of an exceptional point in a PT symmetric directional
coupler(DC) is demonstrated. In such a system the exceptional point can be
probed by varying only a single parameter. Using the Rayleigh-Schroedinger
perturbation theory we prove that the spectrum of a PT symmetric Hamiltonian is
real as long as the radius of convergence has not been reached. We also show
how one can use a PT symmetric DC to measure the radius of convergence for non
PT symmetric structures. For such systems the physical meaning of the rather
mathematical term: radius of convergence, is exemplified.
| v1 (Mon, 18 Feb 2008 11:19:52 GMT) |
802.2458 | Hatziminaoglou Evanthia | E. Hatziminaoglou, J. Fritz, A. Franceschini, A. Afonso-Luis, A.
Hernan-Caballero, I. Perez-Fournon, S. Serjeant, C. Lonsdale, S. Oliver, M.
Rowan-Robinson, D. Shupe, H.E. Smith, J. Surace | Hatziminaoglou E., Fritz J., Franceschini A., Afonso-Luis A., Hernan-Caballero A., Perez-Fournon I., Serjeant S., Lonsdale C., Oliver S., Rowan-Robinson M., Shupe D., Smith H. E., Surace J. | Properties of dusty tori in AGN: I. The Case of SWIRE/SDSS Quasars | Full length tables 1 & 2 were omitted from the on-line issue, they
can be directly retrieved from the CDS ftp site:
http://cdsarc.u-strasbg.fr/viz-bin/ftp-index?J/MNRAS/386/1252 | MNRAS, Volume 386, Issue 3, Page 1252-1264, May 2008 | 10.1111/j.1365-2966.2008.13119.x | astro-ph | We derive the properties of dusty tori in Active Galactic Nuclei (AGN) from
the comparison of observed Spectral Energy Distributions (SEDs) of SDSS quasars
and a precomputed grid of torus models. The observed SEDs comprise SDSS
photometry, 2MASS J, H, and K data, whenever available and mid-Infrared (MIR)
data from the Spitzer Wide-area InfraRed Extragalactic (SWIRE) Survey. The
adopted model is that of Fritz et al., 2006. The fit is performed by standard
chi^2 minimisation, the model however can be multi-component comprising a
stellar and a starburst components, whenever necessary. Models with low
equatorial optical depth, tau_9.7, were allowed as well as ``traditional''
models with tau_9.7 > 1.0, corresponding to A_V > 22 and the results were
compared. Fits using high optical depth tori models only produced dust more
compactly distributed than in the configuration where all tau_9.7 models were
permitted. Tori with decreasing dust density with the distance from the centre
were favoured while there was no clear preference for models with or without
angular variation of the dust density. The computed outer radii of the tori are
of some tens of parsecs large but can reach, in a few cases, a few hundreds of
parsecs. The mass of dust, M_Dust, and infrared luminosity, L_IR, integrated in
the wavelength range between 1 and 1000 micron, do not show significant
variations with redshift, once the observational biases are taken into account.
Objects with 70 micron detections, representing 25% of the sample, are studied
separately and the starburst contribution (whenever present) to the IR
luminosity can reach, in the most extreme but very few cases, 80%.
| v1 (Mon, 18 Feb 2008 11:13:14 GMT), v2 (Thu, 5 Jun 2008 11:53:39 GMT) |
802.2459 | Harald Dimmelmeier | Bernhard Mueller, Harald Dimmelmeier, Ewald Mueller | Mueller Bernhard, Dimmelmeier Harald, Mueller Ewald | Exploring the relativistic regime with Newtonian hydrodynamics: II. An
effective gravitational potential for rapid rotation | 15 pages, 12 figures, minor modifications | null | 10.1051/0004-6361:200809609 | astro-ph gr-qc | We present the generalization of a recently introduced modified gravitational
potential for self-gravitating fluids. The use of this potential allows for an
accurate approximation of general relativistic effects in an otherwise
Newtonian hydrodynamics code also in cases of rapid rotation. We test this
approach in numerical simulations of astrophysical scenarios related to compact
stars, like supernova core collapse with both a simplified and detailed
microphysical description of matter, and rotating neutron stars in equilibrium.
We assess the quality of the new potential, and demonstrate that it provides a
significant improvement compared to previous formulations for such potentials.
Newtonian simulations of compact objects employing such an effective
relativistic potential predict inaccurate pulsation frequencies despite the
excellent agreement of the collapse dynamics and structure of the compact
objects with general relativistic results. We analyze and discuss the reason
for this behavior.
| v1 (Mon, 18 Feb 2008 15:41:23 GMT), v2 (Mon, 8 Sep 2008 17:21:41 GMT) |
802.246 | Matthew Pitkin | Matthew Pitkin, James Clark, Martin A. Hendry, Ik Siong Heng, Chris
Messenger, Jennifer Toher and Graham Woan | Pitkin Matthew, Clark James, Hendry Martin A., Heng Ik Siong, Messenger Chris, Toher Jennifer, Woan Graham | Is there potential complementarity between LISA and pulsar timing? | 5 pages, 2 figures, submitted for the proceedings of the Amaldi 7
conference | J.Phys.Conf.Ser.122:012004,2008 | 10.1088/1742-6596/122/1/012004 | astro-ph gr-qc | We open the discussion into how the Laser Interferometer Space Antenna (LISA)
observations of supermassive black-hole (SMBH) mergers (in the mass range
~10^6-10^8 Msun) may be complementary to pulsar timing-based gravitational wave
searches. We consider the toy model of determining pulsar distances by
exploiting the fact that LISA SMBH inspiral observations can place tight
parameter constraints on the signal present in pulsar timing observations. We
also suggest, as a future path of research, the use of LISA ring-down
observations from the most massive (>~ a few 10^7 Msun) black-hole mergers, for
which the inspiral stage will lie outside the LISA band, as both a trigger and
constraint on searches within pulsar timing data for the inspiral stage of the
merger.
| v1 (Mon, 18 Feb 2008 11:52:52 GMT) |
802.2461 | Stefan Scherer | S. Scherer (Mainz U., Inst. f. Kernphysik) | Scherer S. | Effective Field Theory of the Single-Nucleon Sector | 4 pages, talk at "Chiral Symmetry in Hadron and Nuclear Physics"
(Chiral 07), Osaka, Japan, 13-16 Nov. 2007 | Mod.Phys.Lett.A23:2289-2292,2008 | 10.1142/S0217732308029216 | hep-ph | We address the issue of a consistent power counting scheme in manifestly
Lorentz-invariant baryon chiral perturbation theory. We discuss the inclusion
of vector mesons in the calculation of the nucleon electromagnetic form
factors. We comment on the chiral expansion of the nucleon mass to order
O(q**6).
| v1 (Mon, 18 Feb 2008 11:57:10 GMT) |
802.2462 | Oleg Tsupko | G.S. Bisnovatyi-Kogan and O.Yu. Tsupko | Bisnovatyi-Kogan G. S., Tsupko O. Yu. | Primordial Black Hole: Mass and Angular Momentum Evolution | Gravitation and Cosmology, accepted, 3 pages, Talk presented at the
russian summer school-seminar "Modern theoretical problems of gravitation and
cosmology" (GRACOS-2007), September 9-16, 2007, Kazan-Yalchik, Russia | Grav.Cosmol.14:173-175,2008 | 10.1134/S0202289308020084 | astro-ph gr-qc | The evolution of the primordial low mass black hole (PBH) in hot universe is
considered. Increase of mass and decrease of PBH spin due to the accretion of
radiation dominated matter are estimated with using of results of numerical
simulation of PBH formation and approximate relations for accretion to a
rotating black hole.
| v1 (Mon, 18 Feb 2008 11:58:48 GMT), v2 (Wed, 20 Feb 2008 12:17:11 GMT) |
802.2463 | Daniel Klauser | D. Klauser, W. A. Coish, Daniel Loss | Klauser D., Coish W. A., Loss Daniel | Nuclear spin dynamics and Zeno effect in quantum dots and defect centers | 11 pages, 3 figures | Phys. Rev. B 78, 205301 (2008) | 10.1103/PhysRevB.78.205301 | cond-mat.mes-hall | We analyze nuclear spin dynamics in quantum dots and defect centers with a
bound electron under electron-mediated coupling between nuclear spins due to
the hyperfine interaction ("J-coupling" in NMR). Our analysis shows that the
Overhauser field generated by the nuclei at the position of the electron has
short-time dynamics quadratic in time for an initial nuclear spin state without
transverse coherence. The quadratic short-time behavior allows for an extension
of the Overhauser field lifetime through a sequence of projective measurements
(quantum Zeno effect). We analyze the requirements on the repetition rate of
measurements and the measurement accuracy to achieve such an effect. Further,
we calculate the long-time behavior of the Overhauser field for effective
electron Zeeman splittings larger than the hyperfine coupling strength and
find, both in a Dyson series expansion and a generalized master equation
approach, that for a nuclear spin system with a sufficiently smooth
polarization the electron-mediated interaction alone leads only to a partial
decay of the Overhauser field by an amount on the order of the inverse number
of nuclear spins interacting with the electron.
| v1 (Mon, 18 Feb 2008 12:05:02 GMT) |
802.2464 | Mifuyu Ukai | M. Ukai, et al | Ukai M. | Gamma-Ray Spectroscopy of $^{16}_\Lambda$O and $^{15}_\Lambda$N
Hypernuclei via the $^{16}$O$(K^-, \pi^-)$ reaction | 22 pages, 17 figures | Phys.Rev.C77:054315,2008 | 10.1103/PhysRevC.77.054315 | nucl-ex | he bound-state level structures of the $^{16}_{\Lambda}$O and
$^{15}_{\Lambda}$N hypernuclei were studied by $\gamma$-ray spectroscopy using
a germanium detector array (Hyperball) via the $^{16}$O ($K^-, \pi^- \gamma$)
reaction. A level scheme for $^{16}_{\Lambda}$O was determined from the
observation of three $\gamma$-ray transitions from the doublet of states
($2^-$,$1^-$) at $\sim 6.7$ MeV to the ground-state doublet ($1^-$,$0^-$). The
$^{15}_{\Lambda}$N hypernuclei were produced via proton emission from unbound
states in $^{16}_{\Lambda}$O . Three $\gamma$ -rays were observed and the
lifetime of the $1/2^+;1$ state in $^{15}_{\Lambda}$N was measured by the
Doppler shift attenuation method. By comparing the experimental results with
shell-model calculations, the spin-dependence of the $\Lambda N$ interaction is
discussed. In particular, the measured $^{16}_{\Lambda}$O ground-state doublet
spacing of 26.4 $\pm$ 1.6 $\pm$ 0.5 keV determines a small but nonzero strength
of the $\Lambda N$ tensor interaction.
| v1 (Mon, 18 Feb 2008 15:31:19 GMT) |
802.2465 | Kiyotaka Tanikawa | Kiyotaka Tanikawa and Seppo Mikkola | Tanikawa Kiyotaka, Mikkola Seppo | A trial symbolic dynamics of the planar three-body problem | Conference paper, 8 pages | null | null | nlin.CD | Symbolic dynamics is applied to the planar three-body problem. Symbols are
defined on the planar orbit when it experiences a syzygy crossing. If the body
i is in the middle at the syzygy crossing and the vectorial area of the
triangle made with three bodies changes sign from + to -, number i is given to
this event, whereas if the vectorial area changes sign from - to +, number i+3
is given. We examine the case of free-fall three-body problem for the first few
digits of symbol sequences, and we examine the case with angular momentum only
for the first digit of the symbol sequences. This trial experiments show some
new aspects of the planar three-body problem.
| v1 (Mon, 18 Feb 2008 12:20:29 GMT) |
802.2466 | Emanuela Bianchi | Emanuela Bianchi, Piero Tartaglia, Emanuela Zaccarelli, Francesco
Sciortino | Bianchi Emanuela, Tartaglia Piero, Zaccarelli Emanuela, Sciortino Francesco | Theoretical and numerical study of the phase diagram of patchy colloids:
ordered and disordered patch arrangements | preprint, 32 pages, 6 figures, 3 tables, J. Chem. Phys. in press | null | 10.1063/1.2888997 | cond-mat.soft | We report theoretical and numerical evaluations of the phase diagram for a
model of patchy particles. Specifically we study hard-spheres whose surface is
decorated by a small number f of identical sites ("sticky spots'') interacting
via a short-range square-well attraction. We theoretically evaluate, solving
the Wertheim theory, the location of the critical point and the gas-liquid
coexistence line for several values of f and compare them to results of Gibbs
and Grand Canonical Monte Carlo simulations. We study both ordered and
disordered arrangements of the sites on the hard-sphere surface and confirm
that patchiness has a strong effect on the phase diagram: the gas-liquid
coexistence region in the temperature-density plane is significantly reduced as
f decreases. We also theoretically evaluate the locus of specific heat maxima
and the percolation line.
| v1 (Mon, 18 Feb 2008 12:24:36 GMT) |
802.2467 | David Wood | David R. Wood | Wood David R. | Folding = Colouring | I have discovered that the main result was first proved by Cook and
Evans in 1979 | null | null | math.CO | The foldings of a connected graph $G$ are defined as follows. First, $G$ is a
folding of itself. Let $G'$ be a graph obtained from $G$ by identifying two
vertices at distance 2 in $G$. Then every folding of $G'$ is a folding of $G$.
The folding number of $G$ is the minimum order of a complete folding of $G$.
Theorem: The folding number of every graph equals its chromatic number.
| v1 (Mon, 18 Feb 2008 12:27:45 GMT), v2 (Mon, 25 Feb 2008 09:40:57 GMT) |
802.2468 | Guy Katriel | Michael Demuth, Marcel Hansmann, Guy Katriel | Demuth Michael, Hansmann Marcel, Katriel Guy | On the distribution of eigenvalues of non-selfadjoint operators | null | null | null | math.SP math.FA | We prove quantitative bounds on the eigenvalues of non-selfadjoint bounded
and unbounded operators. We use the perturbation determinant to reduce the
problem to one of studying the zeroes of a holomorphic function.
| v1 (Mon, 18 Feb 2008 12:36:54 GMT) |
802.2469 | Ting Gao | Ting Gao, Feng-Li Yan, and You-Cheng Li | Gao Ting, Yan Feng-Li, Li You-Cheng | Optimal Controlled teleportation via several kinds of three-qubit states | 15 pages | Science in China Series G, 51 (2008) 1529. | 10.1007/s11433-008-0165-8 | quant-ph | The probability of successfully controlled teleportating an unknown qubit
using a general three-particle state is investigated. We give the analytic
expressions of maximal probabilities of successfully controlled teleportating
an unknown qubit via several kinds of tripartite states including a tripartite
GHZ state and a tripartite W-state.
| v1 (Mon, 18 Feb 2008 12:44:29 GMT) |
802.247 | Jonathan Butterworth | Jonathan M. Butterworth, Adam R. Davison, Mathieu Rubin, Gavin P.
Salam | Butterworth Jonathan M., Davison Adam R., Rubin Mathieu, Salam Gavin P. | Jet substructure as a new Higgs search channel at the LHC | 4 pages, 3 figures | Phys.Rev.Lett.100:242001,2008 | 10.1103/PhysRevLett.100.242001 | hep-ph hep-ex | It is widely considered that, for Higgs boson searches at the Large Hadron
Collider, WH and ZH production where the Higgs boson decays to b anti-b are
poor search channels due to large backgrounds. We show that at high transverse
momenta, employing state-of-the-art jet reconstruction and decomposition
techniques, these processes can be recovered as promising search channels for
the standard model Higgs boson around 120 GeV in mass.
| v1 (Mon, 18 Feb 2008 19:57:19 GMT), v2 (Thu, 19 Jun 2008 09:05:18 GMT) |
802.2471 | Xiangcun Meng | X. Meng, X. Chen and Z. Han | Meng X., Chen X., Han Z. | The single-degenerate channel for the progenitor of type Ia supernovae
with different metallicities | 15pages, 12figures, accepted for publication in MNRAS, including
referee's comments | null | 10.1111/j.1365-2966.2009.14636.x | astro-ph | The single-degenerate channel for the progenitors of type Ia supernovae (SNe
Ia) are currently accepted, in which a carbon-oxygen white dwarf (CO WD)
accretes hydrogen-rich material from its companion, increases its mass to the
Chandrasekhar mass limit, and then explodes as a SN Ia. Incorporating the
prescription of \citet{HAC99a} for the accretion efficiency into Eggleton's
stellar evolution code and assuming that the prescription is valid for
\emph{all} metallicities, we performed binary stellar evolution calculations
for more than 25,000 close WD binaries with metallicities $Z=0.06, 0.05, 0.04,
0.03, 0.02, 0.01, 0.004, 0.001, 0.0003$ and 0.0001. For our calculations, the
companions are assumed to be unevolved or slightly evolved stars (WD + MS). As
a result, the initial parameter spaces for SNe Ia at various $Z$ are presented
in orbital period-secondary mass ($\log P_{\rm i}, M_{\rm 2}^{\rm i}$) planes.
Our study shows that both the initial mass of the secondary and the initial
orbital period increase with metallicity. Thus, the minimum mass of the CO WD
for SNe Ia decreases with metallicity $Z$. The difference of the minimum mass
may be as large as 0.24 $M_{\odot}$ for different Z.
Adopting the results above, we studied the birth rate of SNe Ia for various
$Z$ via a binary population synthesis approach. If a single starburst is
assumed, SNe Ia occur systemically earlier and the peak value of the birth rate
is larger for a high $Z$. The Galactic birth rate from the WD + MS channel is
lower than (but comparable to) that inferred from observations. Our study
indicates that supernovae like SN2002ic would not occur in extremely
low-metallicity environments, if the delayed dynamical-instability model in
\citet{HAN06} is appropriate.
| v1 (Mon, 18 Feb 2008 13:14:04 GMT), v2 (Fri, 13 Feb 2009 04:31:17 GMT) |
802.2472 | Mari Carmen Ba\~nuls | Mari-Carmen Ba\~nuls, David P\'erez-Garc\'ia, Michael M. Wolf, Frank
Verstraete, J. Ignacio Cirac | Bañuls Mari-Carmen, Pérez-García David, Wolf Michael M., Verstraete Frank, Cirac J. Ignacio | Sequentially generated states for the study of two dimensional systems | 10 pages, 4 figures | Phys. Rev. A 77, 052306 (2008) | 10.1103/PhysRevA.77.052306 | quant-ph cond-mat.str-el | Matrix Product States can be defined as the family of quantum states that can
be sequentially generated in a one-dimensional system. We introduce a new
family of states which extends this definition to two dimensions. Like in
Matrix Product States, expectation values of few body observables can be
efficiently evaluated and, for the case of translationally invariant systems,
the correlation functions decay exponentially with the distance. We show that
such states are a subclass of Projected Entangled Pair States and investigate
their suitability for approximating the ground states of local Hamiltonians.
| v1 (Mon, 18 Feb 2008 13:07:27 GMT) |
802.2473 | Tetsuya Takimoto | V. Yushankhai, P. Thalmeier, and T. Takimoto | Yushankhai V., Thalmeier P., Takimoto T. | Self-consistent renormalization theory of spin fluctuations in
paramagnetic spinel LiV2O4 | 7 pages, 1 figure. accepted to PRB | null | 10.1103/PhysRevB.77.125126 | cond-mat.str-el | A phenomenological description for the dynamical spin susceptibility
$\chi({\bf q},\omega;T)$ observed in inelastic neutron scattering measurements
on powder samples of LiV$_2$O$_4$ is developed in terms of the parametrized
self-consistent renormalization (SCR) theory of spin fluctuations. Compatible
with previous studies at $T\to 0$, a peculiar distribution in ${\bf q}$-space
of strongly enhanced and slow spin fluctuations at $q \sim Q_c \simeq$ 0.6
$\AA^{-1}$ in LiV$_2$O$_4$ is involved to derive the mode-mode coupling term
entering the basic equation of the SCR theory. The equation is solved
self-consistently with the parameter values found from a fit of theoretical
results to experimental data. For low temperatures, $T \lesssim 30$K, where the
SCR theory is more reliable, the observed temperature variations of the static
spin susceptibility $\chi(Q_c;T)$ and the relaxation rate $\Gamma_Q(T)$ at
$q\sim Q_c$ are well reproduced by those suggested by the theory. For $T\gtrsim
30$K, the present SCR is capable in predicting only main trends in
$T$-dependences of $\chi(Q_c;T)$ and $\Gamma_Q(T)$.
The discussion is focused on a marked evolution (from $q \sim Q_c$ at $T\to
0$ towards low $q$ values at higher temperatures) of the dominant low-$\omega$
integrated neutron scattering intensity $I(q; T)$.
| v1 (Mon, 18 Feb 2008 13:08:38 GMT) |
802.2474 | Yann Rollin | Yann Rollin | Rollin Yann | A remark on the Herzlich volume of asymptotically complex hyperbolic
Einstein manifolds | 4 pages, no figure | null | null | math.DG | We observe inequalities involving the Herzlich volume of a 4-dimensional
asymptotically complex hyperbolic Einstein manifold and its Euler
characteristic provided the metrics is either Kaehler or selfdual. In the
selfdual case we have to assume furthermore that the Kronheimer-Mrowka
invariant is non vanishing.
| v1 (Mon, 18 Feb 2008 14:14:12 GMT) |
802.2475 | Oliver Roth | Oliver Roth, Luis Salinas, Stephan Ruscheweyh | Roth Oliver, Salinas Luis, Ruscheweyh Stephan | A Note on Generating Functions for Hausdorff Moment Sequences | null | Proc. Amer. Math. Soc. 136, 3171-3176, 2008 | null | math.CA math.CV | For functions $f$ whose Taylor coefficients at the origin form a Hausdorff
moment sequence we study the behaviour of $w(y):=|f(\gamma+iy)|$ for $y>0$
($\gamma\leq1$ fixed).
| v1 (Mon, 18 Feb 2008 13:27:16 GMT) |
802.2476 | Georg B\"ocherer | Georg B\"ocherer and Daniel Bielefeld | Böcherer Georg, Bielefeld Daniel | Theoretical Analysis of the Energy Capture in Strictly Bandlimited
Ultra-Wideband Channels | 5 pages. Changes from 2nd version: minor corrections. Essentially the
paper to be presented at ISWCS 2008 in Reykjavik | null | null | cs.IT math.IT | The frequency selectivity of wireless communication channels can be
characterized by the delay spread Ds of the channel impulse response. If the
delay spread is small compared to the bandwidth W of the input signal, that is,
Ds*W approximately equal to 1, the channel appears to be flat fading. For Ds*W
>> 1, the channel appears to be frequency selective, which is usually the case
for wideband signals. In the first case, small scale synchronization with a
precision much higher than the sampling time T = 1/W is crucial. In this paper,
it is shown by analytical means that this is different in the wideband regime.
Here synchronization with a precision of T is sufficient and small scale
synchronization cannot further increase the captured energy at the receiver.
Simulation results show that this effect already occurs for W > 50MHz for the
IEEE 802.15.4a channel model.
| v1 (Mon, 18 Feb 2008 13:34:44 GMT), v2 (Wed, 28 May 2008 09:59:39 GMT), v3 (Thu, 7 Aug 2008 14:03:44 GMT) |
802.2477 | Maria Madjarska | M.S. Madjarska and J.G. Doyle | Madjarska M. S., Doyle J. G. | Small-scale flows in SUMER and TRACE high-cadence co-observations | 7 pages, 6 figures, accepted by A&A | null | 10.1051/0004-6361:200809349 | astro-ph | We report on the physical properties of small-scale transient flows observed
simultaneously at high cadence with the SUMER spectrometer and the TRACE imager
in the plage area of an active region. Our major objective is to provide a
better understanding of the nature of transient phenomena in the solar
atmosphere by using high-cadence imager and spectrometer co-observations at
similar spatial and temporal resolution. A sequence of TRACE Fe IX/X 171 A and
high-resolution MDI images were analysed together with simultaneously obtained
SUMER observations in spectral lines covering a temperature range from 10 000 K
to 1 MK. We reveal the existence of numerous transient flows in small-scale
loops (up to 30 Mm) observed in the plage area of an active region. These flows
have temperatures from 10 000 K (the low temperature limit of our observations)
to 250 000 K. The coronal response of these features is uncertain due to a
blending of the observed coronal line Mg X 624.85 A. The duration of the events
ranges from 60 s to 19 min depending on the loop size. Some of the flows reach
supersonic velocities. The Doppler shifts often associated with explosive
events or bi-directional jets can actually be identified with flows (some of
them reaching supersonic velocities) in small-scale loops. Additionally, we
demonstrate how a line-of-sight effect can give misleading information on the
nature of the observed phenomena if only either an imager or a spectrometer is
used.
| v1 (Mon, 18 Feb 2008 13:24:02 GMT) |
802.2478 | Yves Le Jan | Yves Le Jan (LM-Orsay) | Jan Yves Le | Markov loops and renormalization | null | null | null | math.PR | We study Poissonian ensembles of Markov loops and the associated renormalized
self-intersection local times.
| v1 (Mon, 18 Feb 2008 13:24:56 GMT), v2 (Thu, 20 Mar 2008 15:22:19 GMT), v3 (Thu, 31 Jul 2008 12:23:42 GMT) |
802.2479 | Henri Gouin | Vadim S. Nikolayev, Sergey L. Gavrilyuk, Henri Gouin (MSNMGP, LMMT) | Nikolayev Vadim S., Gavrilyuk Sergey L., Gouin Henri | Modelling of the moving deformed triple contact line: influence of the
fluid inertia | 19 pages and 3 figures | Journal of Colloid and Interface Science 302, 2 (2006) 605-612 | 10.1016/j.jcis.2006.06.046 | physics.class-ph math-ph math.MP | For partial wetting, motion of the triple liquid-gas-solid contact line is
influenced by heterogeneities of the solid surface. This influence can be
strong in the case of inertial (e.g. oscillation) flows where the line can be
pinned or move intermittently. A model that takes into account both surface
defects and fluid inertia is proposed. The viscous dissipation in the bulk of
the fluid is assumed to be negligible as compared to the dissipation in the
vicinity of the contact line. The equations of motion and the boundary
condition at the contact line are derived from Hamilton's principle. The rapid
capillary rise along a vertical inhomogeneous wall is treated as an example.
| v1 (Mon, 18 Feb 2008 13:25:49 GMT) |
802.248 | Maxim M. Korshunov | M.A. Korshunov | Korshunov M. A. | Manifestation of Vacancies in a Spectrum of Organic Molecular Crystal
Lattice Vibrations | 2 pages, PDF | null | null | physics.atm-clus physics.optics | Using a method Raman of spectroscopy and considering a non-uniformity of
allocation of vacancies in a monocrystal, it is shown that lines with the small
intensity (caused by presence of vacancies) have a major intensity in the
sample of a larger size than in the sample of a smaller size. Increase of an
intensity of lines at vacancy concentration increase can reveal which lines are
related to presence of vacancies in the sample. For a p-dichlorobenzene, it is
lines of a small intensity in a spectrum of the lattice oscillations in the
field of 70 cm^{-1}.
| v1 (Mon, 18 Feb 2008 13:40:54 GMT) |
802.2481 | Kristina Frantzen | Kristina Frantzen and Alan Huckleberry | Frantzen Kristina, Huckleberry Alan | K3-surfaces with special symmetry: An example of classification by
Mori-reduction | 14 pages | null | null | math.AG | The classification problem for K3-surfaces equipped with finite groups $H$ of
symplectic symmetry centralized by an antisymplectic involution is considered.
An approach via equivariant Mori-reduction is employed. This method, which has
proved to be successful even for rather small groups, is exemplified here by
giving a complete classification in the case $H = C_3 \ltimes C_7$. The
consideration of this particular group is related to the study of K3-surfaces
with maximal finite groups of symplectic automorphisms. Applications to the
case $L_2(7)$ are given.
| v1 (Mon, 18 Feb 2008 20:39:01 GMT) |
802.2482 | Maxim M. Korshunov | M.A. Korshunov | Korshunov M. A. | Determination of Vacancies Allocation in a Monocrystal of a
P-Dichlorobenzene Using a Method of the Raman Spectroscopy | 2 pages, PDF | null | null | physics.atm-clus physics.optics | The method of Raman scattering is used to investigate the cross edge of a
p-dichlorobenzene monocrystal, which was grown up by a Bridgmen method.
Comparison of intensities of additional lines of a spectrum of the lattice
oscillations of certain parts of an edge of a monocrystal with density of these
fields has allowed to relate some lines to presence of vacancies in structure.
| v1 (Mon, 18 Feb 2008 13:44:31 GMT) |
802.2483 | Francesco Giazotto | F. Giazotto, T. T. Heikkila, G. Pepe. P. Helisto, A. Luukanen, and J.
P. Pekola | Giazotto F., Heikkila T. T., Helisto G. Pepe. P., Luukanen A., Pekola J. P. | Ultrasensitive Proximity Josephson Sensor with Kinetic Inductance
Read-Out | 4 pages, 3 figures | Appl. Phys. Lett. 92, 162507 (2008) | 10.1063/1.2908922 | cond-mat.mes-hall cond-mat.supr-con | We propose a mesoscopic kinetic-inductance radiation detector based on a long
superconductor--normal metal--superconductor Josephson junction. The operation
of this proximity Josephson sensor (PJS) relies on large kinetic inductance
variations under irradiation due to the exponential temperature dependence of
the critical current. Coupled with a dc SQUID readout, the PJS is able to
provide a signal to noise (S/N) ratio up to ~10^3 in the THz regime if operated
as calorimeter, while electrical noise equivalent power (NEP) as low as
~7x10^{-20} W(Hz)^(-1/2) at 200 mK can be achieved in the bolometer operation.
The high performance together with the ease of fabrication make this structure
attractive as an ultrasensitive cryogenic detector of THz electromagnetic
radiation.
| v1 (Mon, 18 Feb 2008 13:50:20 GMT) |
802.2484 | Manoel Robilotta | M. R. Robilotta | Robilotta M. R. | Nuclear Interactions: The Chiral Picture | Talk given at CHIRAL 07 - Osaka - November 2007 | Mod.Phys.Lett.A23:2273-2280,2008 | 10.1142/S0217732308029186 | nucl-th | Chiral expansions of the two-pion exchange components of both two- and
three-nucleon forces are reviewed and a discussion is made of the predicted
pattern of hierarchies. The strength of the scalar-isoscalar central potential
is found to be too large and to defy expectations from the symmetry. The causes
of this effect can be understood by studying the nucleon scalar form factor.
| v1 (Mon, 18 Feb 2008 18:49:59 GMT) |
802.2485 | Sergei Sergeenkov | Fernando M. Araujo-Moreira and Sergei Sergeenkov | Araujo-Moreira Fernando M., Sergeenkov Sergei | Dynamical reentrance and geometry imposed quantization effects in
Nb-AlOx-Nb Josephson junction arrays | null | Superconductor Science and Technology 21 (2008) 045002 | 10.1088/0953-2048/21/4/045002 | cond-mat.supr-con | In this paper, we report on different phenomena related to the magnetic
properties of artificially prepared highly ordered (periodic) two-dimensional
Josephson junction arrays (2D-JJA) of both shunted and unshunted Nb-AlOx-Nb
tunnel junctions. By employing mutual-inductance measurements and using a
high-sensitive bridge, we have thoroughly investigated (both experimentally and
theoretically) the temperature and magnetic field dependence of complex AC
susceptibility of 2D-JJA. We also demonstrate the use of the scanning SQUID
microscope for imaging the local flux distribution within our unshunted arrays.
| v1 (Mon, 18 Feb 2008 13:58:46 GMT), v2 (Tue, 19 Feb 2008 16:41:38 GMT) |
802.2486 | Ivan Garanovich | Alexander Szameit, Ivan L. Garanovich, Matthias Heinrich, Alexander
Minovich, Felix Dreisow, Andrey A. Sukhorukov, Thomas Pertsch, Dragomir N.
Neshev, Stefan Nolte, Wieslaw Krolikowski, Andreas Tunnermann, Arnan Mitchell
and Yuri S. Kivshar | Szameit Alexander, Garanovich Ivan L., Heinrich Matthias, Minovich Alexander, Dreisow Felix, Sukhorukov Andrey A., Pertsch Thomas, Neshev Dragomir N., Nolte Stefan, Krolikowski Wieslaw, Tunnermann Andreas, Mitchell Arnan, Kivshar Yuri S. | Diffraction-managed solitons and nonlinear beam diffusion in modulated
arrays of optical waveguides | null | Phys. Rev. A 78, 031801(1-4) (2008) | 10.1103/PhysRevA.78.031801 | physics.optics | We study propagation of light in nonlinear diffraction-managed photonic
lattices created with arrays of periodically-curved coupled optical waveguides
which were fabricated using femtosecond laser writing in silica glass, and
titanium indiffusion in LiNbO3 crystals. We identify different regimes of the
nonlinear propagation of light beams depending on the input power, and present
the first experimental observation of diffraction-managed solitons, which are
formed as a result of the interplay between the engineered beam diffraction and
nonlinear self-focusing or defocusing. We observe that in self-collimating
structures where linear diffraction is suppressed, a novel regime of nonlinear
beam diffusion takes place at the intermediate powers before the lattice
soliton is formed at higher powers.
| v1 (Mon, 18 Feb 2008 14:01:47 GMT) |
802.2487 | Kazunori Nakayama | Masahiro Kawasaki, Kazunori Nakayama | Kawasaki Masahiro, Nakayama Kazunori | Solving Cosmological Problems of Supersymmetric Axion Models in an
Inflationary Universe | 19 pages, 4 figures | Phys.Rev.D77:123524,2008 | 10.1103/PhysRevD.77.123524 | hep-ph | We revisit inflationary cosmology of axion models in the light of recent
developments on the inflaton decay in supergravity. We find that all the
cosmological difficulties, including gravitino, axino overproduction and
axionic isocurvature fluctuation, can be avoided if the saxion field has large
initial amplitude during inflation and decays before big-bang nucleosynthesis.
| v1 (Mon, 18 Feb 2008 14:04:36 GMT), v2 (Mon, 28 Apr 2008 11:19:16 GMT) |
802.2488 | Yves-Patrick Pellegrini | Francois Willot and Yves-Patrick Pellegrini | Willot Francois, Pellegrini Yves-Patrick | Fast Fourier Transform computations and build-up of plastic deformation
in 2D, elastic-perfectly plastic, pixelwise disordered porous media | 6 pages, 5 figures. Presented at the "11th International Symposium On
Continuum Models and Discrete Systems (CMDS 11)" (Ecole des Mines, Paris,
July 30- August 3 2007) | in D. Jeulin, S. Forest (eds), "Continuum Models and Discrete
Systems CMDS 11", (Ecole des Mines, Paris, 2008), pp. 443-449. [ISBN:
978-2-356-71000-0] | null | cond-mat.mtrl-sci cond-mat.dis-nn | Stress and strain fields in a two-dimensional pixelwise disordered system are
computed by a Fast Fourier Transform method. The system, a model for a ductile
damaged medium, consists of an elastic-perfectly matrix containing void pixels.
Its behavior is investigated under equibiaxial or shear loading. We monitor the
evolution with loading of plastically deformed zones, and we exhibit a
nucleation / growth / coalescence scenario of the latter. Identification of
plastic ``clusters'' is eased by using a discrete Green function implementing
equilibrium and continuity at the level of one pixel. Observed morphological
regimes are put into correspondence with some features of the macroscopic
stress / strain curves.
| v1 (Mon, 18 Feb 2008 14:13:32 GMT) |
802.2489 | Vandana Desai | Vandana Desai, B. T. Soifer, Arjun Dey, Buell T. Jannuzi, Emeric Le
Floc'h, Chao Bian, Kate Brand, Michael J. I. Brown, Lee Armus, Dan W.
Weedman, Richard Cool, Daniel Stern, Mark Brodwin | Desai Vandana, Soifer B. T., Dey Arjun, Jannuzi Buell T., Floc'h Emeric Le, Bian Chao, Brand Kate, Brown Michael J. I., Armus Lee, Weedman Dan W., Cool Richard, Stern Daniel, Brodwin Mark | Redshift Distribution of Extragalactic 24 micron Sources | 21 pages, 11 figures; accepted for publication in ApJ | null | 10.1086/587637 | astro-ph | We present the redshift distribution of a complete, unbiased sample of 24
micron sources down to fnu(24 micron) = 300 uJy (5-sigma). The sample consists
of 591 sources detected in the Bootes field of the NOAO Deep Wide-Field Survey.
We have obtained optical spectroscopic redshifts for 421 sources (71%). These
have a redshift distribution peaking at z~0.3, with a possible additional peak
at z~0.9, and objects detected out to z=4.5. The spectra of the remaining 170
(29%) exhibit no strong emission lines from which to determine a redshift. We
develop an algorithm to estimate the redshift distribution of these sources,
based on the assumption that they have emission lines but that these lines are
not observable due to the limited wavelength coverage of our spectroscopic
observations. The redshift distribution derived from all 591 sources exhibits
an additional peak of extremely luminous (L(8-1000 micron) > 3 x 10^{12} Lsun)
objects at z~2, consisting primarily of sources without observable emission
lines. We use optical line diagnostics and IRAC colors to estimate that 55% of
the sources within this peak are AGN-dominated. We compare our results to
published models of the evolution of infrared luminous galaxies. The models
which best reproduce our observations predict a large population of
star-formation dominated ULIRGs at z > 1.5 rather than the AGN-dominated
sources we observe.
| v1 (Mon, 18 Feb 2008 19:19:05 GMT) |
802.249 | Peter Schwab | Stefan Schenk, Michael Dzierzawa, Peter Schwab, Ulrich Eckern | Schenk Stefan, Dzierzawa Michael, Schwab Peter, Eckern Ulrich | Successes and failures of Bethe Ansatz Density Functional Theory | null | Phys. Rev. B 78, 165102 (2008). | 10.1103/PhysRevB.78.165102 | cond-mat.str-el | The response of a one-dimensional fermion system is investigated using
Density Functional Theory (DFT) within the Local Density Approximation (LDA),
and compared with exact results. It is shown that DFT-LDA reproduces
surprisingly well some of the characteristic features of the Luttinger liquid,
namely the vanishing spectral weight of low energy particle-hole excitations,
as well as the dispersion of the collective charge excitations. On the other
hand, the approximation fails, even qualitatively, for quantities for which
backscattering is important, i.e., those quantities which are crucial for an
accurate description of transport. In particular, the Drude weight in the
presence of a single impurity is discussed.
| v1 (Mon, 18 Feb 2008 14:16:29 GMT) |
802.2491 | Louigi Addario-Berry | L. Addario-Berry, B.A. Reed | Addario-Berry L., Reed B. A. | Ballot theorems for random walks with finite variance | 21 pages; substantially simplified the proof of the positive result | null | null | math.PR | We prove an analogue of the classical ballot theorem that holds for any
random walk in the range of attraction of the normal distribution. Our result
is best possible: we exhibit examples demonstrating that if any of our
hypotheses are removed, our conclusions may no longer hold.
| v1 (Mon, 18 Feb 2008 14:18:13 GMT), v2 (Thu, 28 Feb 2008 13:30:40 GMT) |
802.2492 | Jiulin Du | Zhipeng Liu, Jiulin Du, and Lina Guo | Liu Zhipeng, Du Jiulin, Guo Lina | Nonextensivity and q-distribution of a relativistic gas under an
external electromagnetic field | 9 pages, 39 refences | Chinese Sci. Bull.56(2011)3689 | 10.1007/s11434-011-4750-2 | cond-mat.stat-mech gr-qc | We investigate the nonextensivity and the q-distribution of a relativistic
gas under an external electromagnetic field. We derive a formula expression of
the nonextensive parameter q based on the relativistic generalized Boltzmann
equation, the relativistic q-H theorem and the relativistic version of
q-power-law distribution function in the nonextensive q-kinetic theory. We thus
provide the connection between the parameter 1-q and the differentiation of the
temperature field of the gas as well as the four-potential with respect to time
and space coordinates, and therefore present the nonextensivity for the gas a
clearly physical meaning.
| v1 (Mon, 18 Feb 2008 14:28:19 GMT) |
802.2493 | Liliana Micu | P. Dita and L. Micu | Dita P., Micu L. | Suppressing the spurious states of the centre of mass | 4 pages | null | null | quant-ph | Following Dirac's ideas concerning the quantization of constrained systems,
we suggest to replace the free centre of mass Hamiltonian H_{CM} by another
operator which commutes with all the elements of the algebra generated via the
commutation relations by H_{CM} and the constraints which fix the centre of
mass position. We show that the new Hamiltonian is a multiple of the identity
operator and, as a result, its unique effect is to raise the internal energy
levels by a constant amount.
| v1 (Mon, 18 Feb 2008 14:34:16 GMT) |
802.2494 | Probodh Kuiri Kumar | P. K. Kuiri, B. Joseph, H. P. Lenka, G. Sahu, J. Ghatak, D. Kanjilal,
and D. P. Mahapatra | Kuiri P. K., Joseph B., Lenka H. P., Sahu G., Ghatak J., Kanjilal D., Mahapatra D. P. | Observation of a Universal Aggregation Mechanism and a Possible Phase
Transition in Au Sputtered by Swift Heavy Ions | 4 pages, 3 figures | Phys Rev Lett 100, 245501 (2008) | 10.1103/PhysRevLett.100.245501 | cond-mat.mtrl-sci cond-mat.stat-mech | Two exponents, $\delta$, for size distribution of $n$-atom clusters,
$Y(n)\sim n^{-\delta}$, have been found in Au clusters sputtered from embedded
Au nanoparticles under swift heavy ion irradiation. For small clusters, below
12.5 nm in size, $\delta$ has been found to be 3/2, which can be rationalized
as occurring from a steady state aggregation process with size independent
aggregation. For larger clusters, a $\delta$ value of 7/2 is suggested, which
might come from a dynamical transition to another steady state where
aggregation and evaporation rates are size dependent. In the present case, the
observed decay exponents do not support any possibility of a thermodynamic
liquid-gas type phase transition taking place, resulting in cluster formation.
| v1 (Sun, 17 Feb 2008 09:26:10 GMT), v2 (Fri, 16 Oct 2009 07:10:00 GMT) |
802.2495 | Pascal Moyal | Pascal Moyal | Moyal Pascal | Construction of a stationary FIFO queue with impatient customers | null | null | null | math.PR | In this paper, we study the stability of queues with impatient customers.
Under general stationary ergodic assumptions, we first provide some conditions
for such a queue to be regenerative (i.e. to empty a.s. an infinite number of
times). In the particular case of a single server operating in First in, First
out, we prove the existence (in some cases, on an enlarged probability space)
of a stationary workload. This is done by studying stochastic recursions under
the Palm settings, and by stochastic comparison of stochastic recursions.
| v1 (Mon, 18 Feb 2008 14:43:43 GMT) |
802.2496 | Markus Pak | Christof Gattringer and Markus Pak | Gattringer Christof, Pak Markus | New overlap construction of Weyl fermions | Abstract extended; Version to appear in Nuclear Physics B | Nucl.Phys.B801:353-360,2008 | 10.1016/j.nuclphysb.2008.03.015 | hep-lat hep-ph hep-th | In a recent article Hasenfratz and von Allmen have suggested a fixed point
action for two flavors of Weyl fermions on the lattice with gauge group SU(2).
The block-spin transformation they use maps the chiral and vector symmetries of
the underlying vector theory onto two equations of the Ginsparg-Wilson (GW)
type. We show that an overlap Dirac operator can be constructed which solves
both GW equations simultaneously. We discuss the properties of this overlap
operator and its projection onto lattice Weyl fermions which seems to be free
of artefacts, in particular the projection operators are independent of the
gauge field.
| v1 (Mon, 18 Feb 2008 14:55:06 GMT), v2 (Fri, 28 Mar 2008 16:00:53 GMT) |
802.2497 | Matthew Palotti | M. L. Palotti, F. Heitsch, E. G. Zweibel, Y.-M. Huang | Palotti M. L., Heitsch F., Zweibel E. G., Huang Y. -M. | Evolution of Unmagnetized and Magnetized Shear Layers | 17 pages, 14 figures, to be published in ApJ April 20, 2008, v677n2 | null | 10.1086/529066 | astro-ph | We present numerical simulations of the growth and saturation of the
Kelvin-Helmholtz instability in a compressible fluid layer with and without a
weak magnetic field. In the absence of a magnetic field, the instability
generates a single eddy which flattens the velocity profile, stabilizing it
against further perturbations. Adding a weak magnetic field - weak in the sense
that it has almost no effect on the linear instability - leads to a complex
flow morphology driven by MHD forces and to enhanced broadening of the layer,
due to Maxwell stresses. We corroborate earlier studies which showed that
magnetic fields destroy the large scale eddy structure through periodic cycles
of windup and resistive decay, but we show that the rate of decay decreases
with decreasing plasma resistivity, at least within the range of resistivity
accessible to our simulations. Magnetization increases the efficiency of
momentum transport, and the transport increases with decreasing resistivity.
| v1 (Mon, 18 Feb 2008 15:03:58 GMT) |
802.2498 | Dominik Muth | D. Muth, A. Mering and M. Fleischhauer | Muth D., Mering A., Fleischhauer M. | Ultracold bosons in disordered superlattices: Mott-insulators induced by
tunneling | null | Phys. Ref. A 77, 043618 (2008) | 10.1103/PhysRevA.77.043618 | cond-mat.other cond-mat.dis-nn | We analyse the phase diagram of ultra-cold bosons in a one-dimensional
superlattice potential with disorder using the time evolving block decimation
algorithm for infinite sized systems (iTEBD). For degenerate potential energies
within the unit cell of the superlattice loophole-shaped insulating phases with
non-integer filling emerge with a particle-hole gap proportional to the boson
hopping. Adding a small amount of disorder destroys this gap. For not too large
disorder the loophole Mott regions detach from the axis of vanishing hopping
giving rise to insulating islands. Thus the system shows a transition from a
compressible Bose-glass to a Mott-insulating phase with increasing hopping
amplitude. We present a straight forward effective model for the dynamics
within a unit cell which provides a simple explanation for the emergence of
Mott-insulating islands. In particular it gives rather accurate predictions for
the inner critical point of the Bose-glass to Mott-insulator transition.
| v1 (Mon, 18 Feb 2008 15:34:29 GMT) |
802.2499 | Edward Kinney | HERMES Collaboration: A. Airapetian, et al | HERMES Collaboration , Airapetian A. | Measurement of Azimuthal Asymmetries With Respect To Both Beam Charge
and Transverse Target Polarization in Exclusive Electroproduction of Real
Photons | 24 pages, 10 figures, 2 tables; 1 figure,3 references added, slight
text change | JHEP 0806:066,2008 | 10.1088/1126-6708/2008/06/066 | hep-ex | Azimuthal asymmetries in exclusive electroproduction of real photons are
measured for the first time with respect to transverse target polarisation,
providing new constraints on Generalized Parton Distributions. From the same
data set on a hydrogen target, new results for the beam-charge asymmetry are
also extracted with better precision than those previously reported. By
comparing model calculations with measured asymmetries attributed to the
interference between the deeply virtual Compton scattering and Bethe-Heitler
processes, a model-dependent constraint is obtained on the total angular
momenta carried by up and down quarks in the nucleon.
| v1 (Mon, 18 Feb 2008 15:10:04 GMT), v2 (Thu, 22 May 2008 18:53:17 GMT) |
802.25 | Chihiro Sasaki | C. Sasaki (TU Munich), B. Friman (GSI), K. Redlich (Univ. of Wroclaw
and TU Darmstadt) | Sasaki C., Friman B., Redlich K. | Density fluctuations and a first-order chiral phase transition in
non-equilibrium | 4 pages, 1 figure, to appear in the proceedings of Chiral07, November
13-16 2007, Osaka, Japan | Mod.Phys.Lett.A23:2469-2472,2008 | 10.1142/S0217732308029605 | hep-ph nucl-th | The thermodynamics of a first-order chiral phase transition is considered in
the presence of spinodal phase separation using the Nambu-Jona-Lasinio model in
the mean field approximation. We focus on the behavior of conserved charge
fluctuations. We show that in non-equilibrium the specific heat and charge
susceptibilities diverge as the system crosses the isothermal spinodal lines.
| v1 (Mon, 18 Feb 2008 15:11:46 GMT) |
802.2501 | Garrelt Mellema | A. Peplinski (1), P. Artymowicz (2), G. Mellema (1) ((1) Stockholm
Observatory, (2) Univ. of Toronto at Scarborough) | Peplinski A., Artymowicz P., Mellema G. | Numerical simulations of type III planetary migration: III. Outward
migration of massive planets | 18 pages, 13 figures, submitted to MNRAS | null | 10.1111/j.1365-2966.2008.13339.x | astro-ph | We present a numerical study of rapid, so called type III migration for
Jupiter-sized planets embedded in a protoplanetary disc. We limit ourselves to
the case of outward migration, and study in detail its evolution and physics,
concentrating on the structure of the co-rotation and circumplanetary regions,
and processes for stopping migration. We also consider the dependence of the
migration behaviour on several key parameters. We perform this study using
global, two-dimensional hydrodynamical simulations with adaptive mesh
refinement. We find that the outward directed type III migration can be started
if the initial conditions support $Z > 1$, that corresponds to initial value
$M_\rmn{\Delta} \ga 1.5$. Unlike the inward directed migration, in the outward
migration the migration rate increases due to the growing of the volume of the
co-orbital region. We find the migration to be strongly dependent on the rate
of the mass accumulation in the circumplanetary disc, leading to two possible
regimes of migration, fast and slow. The structure of the co-orbital region and
the stopping mechanism differ between these two regimes.
| v1 (Mon, 18 Feb 2008 15:21:27 GMT) |
802.2502 | Cecile Monthus | Cecile Monthus and Thomas Garel | Monthus Cecile, Garel Thomas | Non equilibrium dynamics of disordered systems : understanding the broad
continuum of relevant time scales via a strong-disorder RG in configuration
space | v2=final version | J. Phys. A: Math. Theor. 41 (2008) 255002 | 10.1088/1751-8113/41/25/255002 | cond-mat.dis-nn | We show that an appropriate description of the non-equilibrium dynamics of
disordered systems is obtained through a strong disorder renormalization
procedure in {\it configuration space}, that we define for any master equation
with transitions rates $W ({\cal C} \to {\cal C}')$ between configurations. The
idea is to eliminate iteratively the configuration with the highest exit rate
$W_{out} ({\cal C})= \sum_{{\cal C}'} W ({\cal C} \to {\cal C}')$ to obtain
renormalized transition rates between the remaining configurations. The
multiplicative structure of the new generated transition rates suggests that,
for a very broad class of disordered systems, the distribution of renormalized
exit barriers defined as $B_{out} ({\cal C}) \equiv - \ln W_{out}({\cal C})$
will become broader and broader upon iteration, so that the strong disorder
renormalization procedure should become asymptotically exact at large time
scales. We have checked numerically this scenario for the non-equilibrium
dynamics of a directed polymer in a two dimensional random medium.
| v1 (Mon, 18 Feb 2008 15:14:16 GMT), v2 (Wed, 8 Oct 2008 13:55:01 GMT) |
Subsets and Splits