Parallel tempering in full QCD with Wilson fermions

TL;DR

This paper evaluates the effectiveness of parallel tempering combined with Hybrid Monte Carlo in simulating full QCD with Wilson fermions, finding limited improvements and discussing alternative approaches.

Contribution

It introduces a framework for applying parallel tempering to full QCD with Wilson fermions and compares its performance to standard methods.

Findings

Parallel tempering does not significantly improve simulation efficiency.

Covariance matrices between sub-ensembles are formulated for analysis.

Discussion of alternative strategies for applying tempering in QCD.

Abstract

We study the performance of QCD simulations with dynamical Wilson fermions by combining the Hybrid Monte Carlo algorithm with parallel tempering on $10^4$ and $12^4$ lattices. In order to compare tempered with standard simulations, covariance matrices between sub-ensembles have to be formulated and evaluated using the general properties of autocorrelations of the parallel tempering algorithm. We find that rendering the hopping parameter $\kappa$ dynamical does not lead to an essential improvement. We point out possible reasons for this observation and discuss more suitable ways of applying parallel tempering to QCD.