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

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 fm)(4) and (2.8 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) MeV and Sigma(1/3) = 248(6) MeV in the (MS) over bar scheme at 2 GeV.