55,567 research outputs found
Beam-Energy and System-Size Dependence of Dynamical Net Charge Fluctuations
We present measurements of net charge fluctuations in collisions at
19.6, 62.4, 130, and 200 GeV, collisions at
62.4, 200 GeV, and collisions at 200
GeV using the net charge dynamical fluctuations measure . The
dynamical fluctuations are non-zero at all energies and exhibit a rather modest
dependence on beam energy. We find that at a given energy and collision system,
net charge dynamical fluctuations violate scaling, but display
approximate scaling. We observe strong dependence of dynamical
fluctuations on the azimuthal angular range and pseudorapidity widths.Comment: 4 pages, 4 figures, presented at the 19th International Conference on
Ultra-Relativistic Nucleus-Nucleus Collisions, "Quark Matter 2008", Jaipur,
India, February 4-10, 200
Pseudorapidity dependence of parton energy loss in relativistic heavy ion collisions
We analyze the recent data from the BRAHMS Collaboration on the
pseudorapidity dependence of nuclear modification factors in Au+Au collisions
at = 200 GeV by using the full three dimensional hydrodynamic
simulations for the density effects on parton energy loss. We first compute the
transverse spectra at and 2.2, and next take a ratio
, where is a nuclear
modification factor. It is shown that hydrodynamic components account for
at low and that quenched pQCD components lead
at high which are consistent with the data.
Strong suppression at is compatible with the parton energy loss in
the final state.Comment: 5 pages, 4 figures; one figure adde
Systematic study of the jet fragmentation function for inclusive jet-production in p+p collisions at sqrt{s}=200 GeV in STAR
Jet fragmentation functions measured in e^+e^- and p+\bar{p} experiments are
well-described on an inclusive hadron level by QCD-based calculations.
Fragmentation is expected to be modified by the presence of a strongly
interacting medium, but full theoretical description of this modification must
still be developed. It has recently been suggested that particle-identified
fragmentation functions may provide additional insight into the processes
underlying jet quenching. To assess the applicability of QCD-based
fragmentation calculations to RHIC data, and to provide a baseline with which
to compare fragmentation function measurements in heavy ion collisions, we
present the first measurements of charged hadron and particle-identified
fragmentation functions of jets reconstructed via a midpoint-cone algorithm
from p+p collisions at 200 GeV in STAR. We study the dependence on jet
cone-size and jet-energy, and compare the results to PYTHIA simulations based
on the Modified Leading Log Approximation (MLLA).Comment: 6 pages, 5 figures, proceedings of Hard Probes 2008 conferenc
Status of Spin Physics - Experimental Summary
The current status of spin physics experiments, based on talks presented at
the Third Circum-Pan-Pacific Symposium on High Energy Spin Physics held in
Beijing, 2001, is summarized in this article. Highlights of recent experimental
results at SLAC, JLab, and DESY, as well as future plans at these facilities
and at RHIC-spin are discussed.Comment: 18 pages, 7 figures, Invited talk presented at the Third
Circum-Pan-Pacific Symposium on High Energy Spin Physics held in Beijing,
October, 200
Large Deviations in the Superstable Weakly Imperfect Bose Gas
The superstable Weakly Imperfect Bose Gas {(WIBG)} was originally derived to
solve the inconsistency of the Bogoliubov theory of superfluidity. Its
grand-canonical thermodynamics was recently solved but not at {point of} the
{(first order)} phase transition. This paper proposes to close this gap by
using the large deviations formalism and in particular the analysis of the Kac
distribution function. It turns out that, as a function of the chemical
potential, the discontinuity of the Bose condensate density at the phase
transition {point} disappears as a function of the particle density. Indeed,
the Bose condensate continuously starts at the first critical particle density
and progressively grows but the free-energy per particle stays constant until
the second critical density is reached. At higher particle densities, the Bose
condensate density as well as the free-energy per particle both increase
{monotonously}
RHIC physics overview
The results from data taken during the last several years at the Relativistic
Heavy-Ion Collider (RHIC) will be reviewed in the paper. Several selected
topics that further our understanding of constituent quark scaling, jet
quenching and color screening effect of heavy quarkonia in the hot dense medium
will be presented. Detector upgrades will further probe the properties of Quark
Gluon Plasma. Future measurements with upgraded detectors will be presented.
The discovery perspectives from future measurements will also be discussed.Comment: 9 pages, 4 figures, invited review article, published by Frontier of
Physics in Chin
Orbital Response of Evanescent Cooper Pairs in Paramagnetically Limited Al Films
We report a detailed study of the pairing resonance via tunneling density of
states in ultra-thin superconducting Al films in supercritical magnetic fields.
Particular emphasis is placed on effects of the perpendicular component of the
magnetic field on the resonance energy and magnitude. Though the resonance is
broadened and attenuated by as expected, its energy is shifted upward
linearly with . Extension of the original theory of the resonance to
include strong perpendicular fields shows that at sufficiently large
the overlap of the broadened resonance tail with the underlying degenerate
Fermi sea alters the spectral distribution of the resonance via the exclusion
principle. This leads to the shift of the the resonance feature to higher
energy.Comment: 8 pages, 4 figure
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