A. Krasnitz

Studying Quarks and Gluons On Mimd Parallel Computers

Numerical simulations of interacting quarks and glu ons may be the best way to calculate the structure of protons and neutrons, as well as the nature of the very early universe or the interiors of neutron stars. Such simulations are limited by the availability of computer power. We are carrying out a program of simulations on multiple instruction, multiple data (MIMD) parallel computers. We describe here the goals of this project, discuss the way in which the computations are adapted to parallel computers and the performance they achieve, and present a few preliminary results.

Thermodynamics of lattice QCD with two light quarks on a 16(3) x 8 lattice.

We have extended our earlier simulations of the high temperature behaviour of lattice QCD with two light flavours of staggered quarks on a

Sphaleron transitions in a realistic heat bath

16^3 \times 8

Hadron spectrum in QCD with valence Wilson fermions and dynamical staggered fermions at 6/g2=5.6.

lattice to lower quark mass (m_q=0.00625). The transition from hadronic matter to a quark-gluon plasma is observed at

Simple hadronic matrix elements with Wilson valence quarks and dynamical staggered fermions at 6/g2=5.6.

6/g^2=5.49(2)

QCD thermodynamics with two flavors of Wilson quarks at Nt=6.

corresponding to a temperature of

Hadron spectroscopy with dynamical Wilson fermions at β = 5.3☆

T_c \approx 140

Hadronic spectroscopy at a ≈ 0.15 fm.

MeV. We present measurements of observables which probe the nature of the quark-gluon plasma and serve to distinguish it from hadronic matter. Although the transition is quite abrupt, we have seen no indications that it is first order.

A realistic heat bath: theory and application to kink-antikink dynamics

Abstract We measure the diffusion rate of Chern-Simons number in the (1 + 1)-dimensional Abelian Higgs model interacting with a realistic heat bath for temperatures between 1 13 and 1 3 times the sphaleron energy. It is found that the measured rate is close to that predicted by a one-loop calculation at the lower end of the temperature range considered but falls at least an order of magnitude short of the one-loop estimate at the upper end of that range. We show numerically that the sphaleron approximation breaks down as soon as the gauge-invariant two-point function yields a correlation length close to the sphaleron size.

QCD hadron spectroscopy with staggered dynamical quarks at β = 5.6☆

We present an analysis of hadronic spectroscopy for Wilson valence quarks with dynamical staggered fermions at a lattice coupling 6/{ital g}{sup 2}={beta}=5.6 at a sea-quark mass of {ital am}{sub {ital q}}=0.01 and 0.025, and of Wilson valence quarks in the quenched approximation at {beta}=5.85 and 5.95, both on 16{sup 3}{times}32 lattices. We make comparisons with our previous results with dynamical staggered fermions at the same parameter values but on 16{sup 4} lattices doubled in the temporal direction.