The vector and axial currents in Wilson chiral perturbation theory

We reconsider the construction and matching of the vector and axial currents in Wilson Chiral Perturbation Theory (WChPT), the low-energy effective theory for lattice QCD with Wilson fermions. In particular, we discuss in detail the impact of the finite renormalization of the currents on their matching from the lattice theory to WChPT.We explicitly show that imposing chiral Ward-Takahashi identities on the currents leads, in general, to additional terms of O(a) in the axial current. We illustrate the impact on physical quantities by computing the pion decay constant to one-loop order in the two flavor theory. Our result differs from previously published ones.