Non-perturbative O(a) improvement of lattice QCD Original Research Article

The coefficients multiplying the counterterms required for O(a) improvement of the action and the isovector axial current in lattice QCD are computed non-perturbatively, in the quenched approximation and for bare gauge couplings g0 i range 0 ⩽ g0 ⩽ 1. A finite-size method based on the Schrödinger functional is employed, which enables us to perform all calculations at z nearly zero quark mass. As a by-product the critical hopping parameter κc is obtained at all couplings considered.