We study three sources of error in our calculation of BK using HYP-smeared staggered fermions on the MILC asqtad lattices. These are (1) dependence on the light sea quark mass; (2) finite volume effects; and (3) the impact of an order of magnitude increase in the number of measurements. Our main results are (1) the dependence on the light sea-quark mass is weaker than expected by naive dimensional analysis, (2) including finite volume effects in SU(2) staggered chiral perturbation theory fits leads to a very small change in BK, of size ≈0.1, and (3) increasing the statistics on one of the coarse MILC lattices resolves a potential discrepancy with other coarse results.
Cite
@article{arxiv.1010.4780,
title = {Systematic Uncertainties in $B_K$ with Improved Staggered Fermions},
author = {Yong-Chull Jang and Taegil Bae and Hyung-Jin Kim and Jangho Kim and Jongjeong Kim and Kwangwoo Kim and Boram Yoon and Weonjong Lee and Chulwoo Jung and Stephen R. Sharpe},
journal= {arXiv preprint arXiv:1010.4780},
year = {2011}
}