Impact of large cutoff-effects on algorithms for improved Wilson fermions

Abstract

As a feasibility study for a scaling test we investigate the behavior of algorithms for dynamical fermions in the N f = 2 Schrödinger functional at an intermediate volume of 1 fm 4 . Simulations were performed using HMC with two pseudo-fermions and PHMC at lattice spacings of approximately 0.1 and 0.07 fm . We show that some algorithmic problems are due to large cutoff-effects in the spectrum of the improved Wilson–Dirac operator and disappear at the smaller lattice spacing. The problems discussed here are not expected to be specific to the Schrödinger functional.