13,769 research outputs found
Production at High in Central Au+Au and collisions at GeV in STAR
he production at high- (5.0 10.0 GeV/)
measured in minimum bias , Au+Au and central Au+Au collisions in the STAR
detector are presented. The ratio measured in is compared to
PYTHIA calculations as a test of perturbative quantum chromodynamics (pQCD)
that describes reasonably well particle production from hard processes. The
nuclear modification factor are also presented. In collisions,
charged pions and (anti-)protons are measured in the range 5.0
15.0 GeV/ and the anti-particle to particle ratio and the baryon to meson
ratios of these hadrons are discussed.Comment: 4 pages, 8 figures, proccedings for QM200
Exploring the QCD landscape with high-energy nuclear collisions
Quantum chromodynamics (QCD) phase diagram is usually plotted as temperature
(T) versus the chemical potential associated with the conserved baryon number
(\mu_{B}). Two fundamental properties of QCD, related to confinement and chiral
symmetry, allows for two corresponding phase transitions when T and \mu_{B} are
varied. Theoretically the phase diagram is explored through non-perturbative
QCD calculations on lattice. The energy scale for the phase diagram
(\Lambda_{QCD} ~ 200 MeV) is such that it can be explored experimentally by
colliding nuclei at varying beam energies in the laboratory. In this paper we
review some aspects of the QCD phase structure as explored through the
experimental studies using high energy nuclear collisions. Specifically, we
discuss three observations related to the formation of a strongly coupled
plasma of quarks and gluons in the collisions, experimental search for the QCD
critical point on the phase diagram and freeze-out properties of the hadronic
phase.Comment: Submitted to the New Journal of Physics focus issue "Strongly
Correlated Quantum Fluids: From Ultracold Quantum Gases to QCD Plasmas
Decoherence and Quantum Fluctuations
We show that the zero-point fluctuations of the intrinsic electromagnetic
environment limit the phase coherence time in all mesoscopic systems at low
temperatures. We derive this quantum noise limited dephasing time and its
temperature dependence in the crossover to the thermal regime. Our results
agree well with most experiments in 1D systems.Comment: 4 pages & 1 figur
Privacy Preserving Auction Based Virtual Machine Instances Allocation Scheme for Cloud Computing Environment
Cloud Computing Environment provides computing resources in the form of Virtual Machines (VMs), to the cloud users through Internet. Auction-based VM instances allocation allows different cloud users to participate in an auction for a bundle of Virtual Machine instances where the user with the highest bid value will be selected as the winner by the auctioneer (Cloud Service Provider) to gain more. In this auction mechanism, individual bid values are revealed to the auctioneer in order to select the winner as a result of which privacy of bid values are lost. In this paper, we proposed an auction scheme to select the winner without revealing the individual bid values to the auctioneer to maintain privacy of bid values. The winner will get the access to the bundle of VM instances. This scheme relies on a set of cryptographic protocols including Oblivious Transfer (OT) protocol and Yao’s protocol to maintain privacy of bid values
New bounds on the neutrino magnetic moment from the plasma induced neutrino chirality flip in a supernova
The neutrino chirality-flip process under the conditions of the supernova
core is investigated in detail with the plasma polarization effects in the
photon propagator taken into account, in a more consistent way than in earlier
publications. It is shown in part that the contribution of the proton fraction
of plasma is essential. New upper bounds on the neutrino magnetic moment are
obtained: mu_nu < (0.5 - 1.1) 10^{-12} mu_B from the limit on the supernova
core luminosity for nu_R emission, and mu_nu < (0.4 - 0.6) 10^{-12} mu_B from
the limit on the averaged time of the neutrino spin-flip. The best upper bound
on the neutrino magnetic moment from SN1987A is improved by the factor of 3 to
7.Comment: 19 pages, LaTeX, 7 EPS figures, submitted to Journal of Cosmology and
Astroparticle Physic
Energy Dependence of High Moments for Net-proton Distributions
High moments of multiplicity distributions of conserved quantities are
predicted to be sensitive to critical fluctuations. To understand the effect of
the complicated non-critical physics backgrounds on the proposed observable, we
have studied various moments of net-proton distributions with AMPT, Hijing,
Therminator and UrQMD models, in which no QCD critical point physics is
implemented. It is found that the centrality evolution of various moments of
net-proton distributions can be uniformly described by a superposition of
emission sources. In addition, in the absence of critical phenomena, some
moment products of net-proton distribution, related to the baryon number
susceptibilities ratio in Lattice QCD calculation, are predicted to be constant
as a function of the collision centrality. We argue that a non-monotonic
dependence of the moment products as a function collision centrality and the
beam energy may be used to locate the QCD critical point.Comment: SQM2009 Proceeding, 6 pages, 5 figure
Performance of the WaveBurst algorithm on LIGO data
In this paper we describe the performance of the WaveBurst algorithm which
was designed for detection of gravitational wave bursts in interferometric
data. The performance of the algorithm was evaluated on the test data set
collected during the second LIGO Scientific run. We have measured the false
alarm rate of the algorithm as a function of the threshold and estimated its
detection efficiency for simulated burst waveforms.Comment: proceedings of GWDAW, 2003 conference, 13 pages, 6 figure
LIGO End-to-End simulation Program
A time-domain simulation program has been developed to provide an accurate description of interferometric gravitational wave detectors. This is being utilized to build a model of LIGO with the aim of aiding in the shakedown and integration of the interferometer subsystems, and ultimately the optimization of detector sensitivity
Constraint Likelihood analysis for a network of gravitational wave detectors
We propose a coherent method for the detection and reconstruction of
gravitational wave signals for a network of interferometric detectors. The
method is derived using the likelihood functional for unknown signal waveforms.
In the standard approach, the global maximum of the likelihood over the space
of waveforms is used as the detection statistic. We identify a problem with
this approach. In the case of an aligned pair of detectors, the detection
statistic depends on the cross-correlation between the detectors as expected,
but this dependence dissappears even for infinitesimally small misalignments.
We solve the problem by applying constraints on thelikelihood functional and
obtain a new class of statistics. The resulting method can be applied to the
data from a network consisting of any number of detectors with arbitrary
detector orientations. The method allows us reconstruction of the source
coordinates and the waveforms of two polarization components of a gravitational
wave. We study the performance of the method with numerical simulation and find
the reconstruction of the source coordinates to be more accurate than in the
standard approach.Comment: 13 pages, 6 figure
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