Comparison of exact hybrid and Langevin algorithms for QCD with Kogut-Susskind fermions

Abstract

We find that the exact hybrid algorithm in simulating QCD with four flavors of Kogut-Susskind fermions at Nt=4, with mqa=0.025 in lattice units, is significantly more efficient than the exact Langevin algorithm, by at least a factor of 10. Comparing the integrated autocorrelation time for the plaquette A and the Wilson line WI on a 44 lattice, we find for the exact hybrid algorithm A10 and WI30, while for the exact Langevin algorithm A150 and WI300. On a 163×4 lattice, even if we were not able to collect enough statistics to measure the autocorrelation times reliably, the exact hybrid algorithm appears again to be more efficient by one order of magnitude. © 1991 The American Physical Society.