Low energy chiral constants from epsilon-regime simulations with improved Wilson fermions

Abstract

We present a lattice QCD calculation of the low-energy constants of the leading order chiral Lagrangian. In these simulations the epsilon regime is reached by using tree-level improved nHYP Wilson fermions combined with reweighting in the quark mass. We analyze two point functions on two ensembles with lattices of size $(1.85\text{ }\text{ }\mathrm{fm}{)}^{4}$ and $(2.8\text{ }\text{ }\mathrm{fm}{)}^{4}$, and at several quark mass values between 4 and 20 MeV. The data are well fitted with next-to-leading order chiral perturbative formulas and predict $F=90(4)\text{ }\text{ }\mathrm{MeV}$ and ${\ensuremath{\Sigma}}^{1/3}=248(6)\text{ }\text{ }\mathrm{MeV}$ in the $\overline{\mathrm{MS}}$ scheme at 2 GeV.