Non-perturbative improvement of the axial current in N_f=3 lattice QCD with Wilson fermions and tree-level improved gauge action

TL;DR

This paper non-perturbatively determines the coefficient c_A for O(a) improvement of the axial current in N_f=3 lattice QCD with Wilson fermions, using Schrödinger functional boundary conditions and a zero topological charge sector approach.

Contribution

It provides the first non-perturbative determination of c_A for N_f=3 Wilson fermions with a tree-level improved gauge action, enhancing the accuracy of lattice QCD simulations.

Findings

Non-perturbative c_A(g_0^2) interpolation formula

Improved axial current for N_f=3 Wilson fermions

Reduced topological sector tunneling issues

Abstract

The coefficient c_A required for O(a) improvement of the axial current in lattice QCD with N_f=3 flavors of Wilson fermions and the tree-level Symanzik-improved gauge action is determined non-perturbatively. The standard improvement condition using Schroedinger functional boundary conditions is employed at constant physics for a range of couplings relevant for simulations at lattice spacings of ~ 0.09 fm and below. We define the improvement condition projected onto the zero topological charge sector of the theory, in order to avoid the problem of possibly insufficient tunneling between topological sectors in our simulations at the smallest bare coupling. An interpolation formula for c_A(g_0^2) is provided together with our final results.