30,928 research outputs found
Equation of state from lattice QCD
Recent results on the equation of state from lattice QCD are reviewed. The
lattice technique and previous results are shortly discussed. New results for
physical quark masses and two sets of lattice spacings are presented. The
pressure, energy density, entropy density, speed of sound and quark number
susceptibilities are determined.Comment: 10 pages, 11figures. Plenary talk presented at the Quark Matter 2005
conferenc
Finite temperature and chemical potential in lattice QCD and its critical point
We propose a method to study lattice QCD at finite temperature (T) and
chemical potential (\mu). We compare the method with direct results and with
the Glasgow method by using n_f=4 QCD at Im(\mu)\neq0. We locate the critical
endpoint (E) of QCD on the Re(\mu)-T plane. We use n_f=2+1 dynamical staggered
quarks with semi-realistic masses on L_t=4 lattices. Our results are based on
{\cal{O}}(10^3-10^4) configurations.Comment: 8 pages, 4 figures. Talk given at the XXX. Hirschegg Workshop on
Ultrarelativistic Heavy-Ion Collisions, January 13-19, 200
Propagation of ultrahigh energy cosmic rays and compact sources
The clustering of ultrahigh energy (>10^{20} eV) cosmic rays (UHECR) suggests
that they might be emitted by compact sources. Statistical analysis (Dubovsky
et al., 2000) estimated the source density. We extend their analysis to give
also the confidence intervals (CI) for the source density using a.) no
assumptions on the relationship between clustered and unclustered events; b.)
nontrivial distributions for the source luminosities and energies; c.) the
energy dependence of the propagation. We also determine the probability that a
proton created at a distance r with energy E arrives at earth above a threshold
E_c. Using this function one can determine the observed spectrum just by one
numerical integration for any injection spectrum. The observed 14 UHECR events
above 10^{20} eV with one doublet gives for the source densities
180_{-165}^{+2730}\cdot 10^{-3} Mpc^{-3} (on the 68% confidence level).Comment: 4 pages, 1 figure, talk to be presented at the 27th International
Cosmic Ray Conference, Hamburg, Germany, August 7-15, 200
Lattice QCD results at finite T and \mu
We propose a method to study lattice QCD at finite temperature (T) and
chemical potential (\mu). We test the method and compare it with the Glasgow
method using n_f=4 staggered QCD with imaginary \mu. The critical endpoint (E)
of QCD on the Re(\mu)-T plane is located. We use n_f=2+1 dynamical staggered
quarks with semi-realistic masses on L_t=4 lattices. Our results are based on
{\cal{O}}(10^3-10^4) configurations.Comment: 9 pages, 4 figures. Talk given at Budapest'02 Workshop on Quark and
Hadron Dynamics, Budapest, March 3-7, 200
Ultrahigh energy cosmic rays as a Grand Unification signal
We analyze the spectrum of the ultrahigh energy (above \approx 10^{9} GeV)
cosmic rays. With a maximum likelihood analysis we show that the observed
spectrum is consistent with the decay of extragalactic GUT scale particles. The
predicted mass for these superheavy particles is m_X=10^b GeV, where
b=14.6_{-1.7}^{+1.6}.Comment: 4 pages, 3 figures, talk to be presented at the 27th International
Cosmic Ray Conference, Hamburg, Germany, August 7-15, 200
The critical point of lattice QCD on the \mu-T plane
We propose a method to study lattice QCD at finite temperature and chemical
potential. We compare it with direct results and with the Glasgow method by
using n_f=4 QCD at Im(\mu)\neq 0. We locate the critical endpoint (E) of QCD on
the Re(\mu)-T plane. In this study we use n_f=2+1 dynamical staggered quarks
with semi-realistic masses on L_t=4 lattices.Comment: 5 pages, 3 Figures. Talk given at EPS HEP2001, July 12-18,2001
Budapes
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