We present non-perturbative results for the constants needed for on-shell O(a) improvement of bilinear operators composed of Wilson fermions. We work at β=6.0 and 6.2 in the quenched approximation. The calculation is done by imposing axial and vector Ward identities on correlators similar to those used in standard hadron mass calculations. A crucial feature of the calculation is the use of non-degenerate quarks. We also obtain results for the constants needed for off-shell O(a) improvement of bilinears, and for the scale and scheme independent renormalization constants, (Z_A), (Z_V) and (Z_S/Z_P). Several of the constants are determined using a variety of different Ward identities, and we compare their relative efficacies. In this way, we find a method for calculating cV that gives smaller errors than that used previously. Wherever possible, we compare our results with those of the ALPHA collaboration (who use the Schr\"odinger functional) and with 1-loop tadpole-improved perturbation theory.
@article{arxiv.hep-lat/0009038,
title = {Order a improved renormalization constants},
author = {Tanmoy Bhattacharya and Rajan Gupta and Weonjong Lee and Stephen Sharpe},
journal= {arXiv preprint arXiv:hep-lat/0009038},
year = {2007}
}
Comments
48 pages. Modified "axis" source for figures also included. Typos corrected (version published in Phys. Rev. D)