Twisted-mass reweighting for O(a) improved Wilson fermions

TL;DR

This paper evaluates a twisted-mass reweighting technique for improved Wilson fermions in lattice QCD, demonstrating increased algorithm stability and controlled reweighting factors without increasing statistical uncertainty.

Contribution

It introduces and tests a twisted-mass reweighting method for Wilson fermions, showing improved stability and manageable reweighting factors in lattice QCD simulations.

Findings

Reweighting improves algorithm stability at fixed acceptance rate.

Reweighting factors remain well-controlled with limited fluctuations.

Uncertainty in pion correlator is comparable to standard methods.

Abstract

We test the reweighting of the quark determinant of O(a) improved Wilson fermions in the domain-decomposed hybrid Monte-Carlo algorithm. Specifically, we implement a reweighting in a twisted-mass parameter proposed by Palombi and L\"uscher in $N_{\rm f}=2$ QCD. We find that at equal acceptance rate, the algorithm is significantly more stable on a $32\times64^3$ lattice upon switching on the reweighting parameter. At the same time, the reweighting factor does not fluctuate strongly and hence is under control. At equal statistics, the uncertainty on the pion correlator is comparable to the case of the standard, unreweighted algorithm.