QCD with dynamical Wilson fermions - first results from SESAM

TL;DR

This paper presents initial results from a full QCD simulation with two sea-quark flavors using Wilson fermions, demonstrating the feasibility and statistical significance of such simulations on high-performance computing resources.

Contribution

First implementation of full QCD with Wilson fermions at this coupling on a large lattice, with performance optimization and analysis of autocorrelation times and systematic errors.

Findings

Autocorrelation times are less than 20 units, exponential autocorrelation times about 50 units.

Preliminary estimates of lattice spacings at different dynamical parameters.

First measurements of the central potential and meson correlators in this setup.

Abstract

First results of a recently started simulation of full QCD with two flavours of sea-quarks at a coupling of $\beta = 5.6$ on a $16^3 \times 32$ lattice are presented. Emphasis is laid on the statistical significance that can be achieved by an ``integrated luminosity'' of 140 TFlop$\times$hrs, for Hybrid Monte Carlo simulations at four intermediate values of $\frac{m_{\pi}}{m_{\rho}}$. The simulation takes place on the Quadrics QH2 at DESY/Zeuthen and DFG/Bielefeld. The performance is optimized by means of BiCGStab and the chronological inversion method of Brower et al. We discuss the systematic errors arising from lack of the molecular dynamic's reversibility on the 32-bit QH2. For plaquette and meson correlators we find integrated autocorrelation times of $< 20$ units of molecular dynamics time and exponential autocorrelation times of about $50$ units. Using these results we perform preliminary measurements of the central potential and $\pi$ and $\rho$ correlators on independent configurations and obtain first estimates of the lattice spacings at three values of the dynamical hopping parameter.