Scaling behavior of discretization errors in renormalization and   improvement constants
  Non-perturbative results for improvement and renormalization constants needed for on-shell and off-shell O(a) improvement of bilinear operators composed of Wilson fermions are presented. The calculations have been done in the quenched approximation at beta=6.0, 6.2 and 6.4. To quantify residual discretization errors we compare our data with results from other non-perturbative calculations and with one-loop perturbation theory. 
Tanmoy Bhattacharya, Rajan Gupta, Weonjong Lee, Stephen R. Sharpe