Further results on O ( a ) improved lattice QCD to one - loop order of perturbation theory

We present results at one-loop order of perturbation theory for various improvement coefficients in on-shell O(a) improved lattice QCD. In particular we determine the additive counterterm required for on-shell improvement of the isovector vector current. Employing a general mass-independent renormalization scheme we also obtain the coefficients of the O(a) counterterms which are proportional to the quark mass in the improved isovector pseudoscalar, axial vector and vector operators. In the latter case a comparison with a recent non-perturbative study is made.