6,879 research outputs found
QCD Thermodynamics at and 12
We present results from studies of high temperature QCD with two flavors of
Kogut-Susskind quarks on lattices at a quark mass of
and on lattices at quark masses and
0.016. The value of the crossover temperature is consistent with that obtained
on coarser lattices and/or at larger quark masses. Results are presented for
the chiral order parameter and for the baryon number susceptibility.Comment: 3-pages, uuencoded compressed postscript file, contribution to
Lattice'94 conferenc
A new effect in the low magnetic field ultrasonic attenuation of impure superconducting niobium
Low magnetic field ultrasonic attenuation of impure superconducting niobiu
Extrapolation Methods for the Dirac Inverter in Hybrid Monte Carlo
In Hybrid Monte Carlo(HMC) simulations for full QCD, the gauge fields evolve
smoothly as a function of Molecular Dynamics (MD) time. Thus we investigate
improved methods of estimating the trial solutions to the Dirac propagator as
superpositions of the solutions in the recent past. So far our best
extrapolation method reduces the number of Conjugate Gradient iterations per
unit MD time by about a factor of 4. Further improvements should be forthcoming
as we further exploit the information of past trajectories.Comment: latex file with espcrc2 styl
Two-Flavor Staggered Fermion Thermodynamics at N_t = 12
We present results of an ongoing study of the nature of the high temperature
crossover in QCD with two light fermion flavors. These results are obtained
with the conventional staggered fermion action at the smallest lattice spacing
to date---approximately 0.1 fm. Of particular interest are a study of the
temperature of the crossover a determination of the induced baryon charge and
baryon susceptibility, the scalar susceptibility, and the chiral order
parameter, used to test models of critical behavior associated with chiral
symmetry restoration. From our new data and published results for N_t = 4, 6,
and 8, we determine the QCD magnetic equation of state from the chiral order
parameter using O(4) and mean field critical exponents and compare it with the
corresponding equation of state obtained from an O(4) spin model and mean field
theory. We also present a scaling analysis of the Polyakov loop, suggesting a
temperature dependent ``constituent quark free energy.''Comment: LaTeX 25 pages, 15 Postscript figure
Resonance Scattering on the Lattice with Non-Zero Total Momentum
Most hadronic particles are resonances: for example, the rho meson appears as
a resonance in the elastic scattering of two pions. A method by Luescher
enables one to measure the properties of the resonance particles from finite
lattices. We present here a more general method which includes scattering
processes where the total momentum of the particles is non-zero. The main
advantage is that the resonance scattering can be observed in a considerably
smaller spatial volume. We test the method with a simple 3+1 dimensional spin
model, and find excellent agreement between the zero momentum and the non-zero
momentum scattering sectors.Comment: 4 pages uuencoded postscript, contribution to LATTICE 9
The beta function and equation of state for QCD with two flavors of quarks
We measure the pressure and energy density of two flavor QCD in a wide range
of quark masses and temperatures. The pressure is obtained from an integral
over the average plaquette or psi-bar-psi. We measure the QCD beta function,
including the anomalous dimension of the quark mass, in new Monte Carlo
simulations and from results in the literature. We use it to find the
interaction measure, E-3p, yielding non-perturbative values for both the energy
density E and the pressure p. uuencoded compressed PostScript file Revised
version should work on more PostScript printers.Comment: 24 page
Scaling of Pseudo-Critical Couplings in Two-Flavour QCD
We study the scaling behaviour of the pseudo-critical couplings for the
chiral phase transition in two-flavour QCD. We show that all existing results
from lattice simulations on lattices with temporal extent , 6 and 8
can be mapped onto a universal scaling curve. The relevant combination of
critical exponents, , is consistent with the scaling behaviour
expected for a second order phase transition with exponents. At present,
scaling according to the symmetry group can, however, not be ruled out.Comment: 8 pages, NSF-ITP 93-12
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