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

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.

Determinant reweighting for O(a) improved Wilson fermions