Update on $B_K$ and ${\epsilon }_K$ with staggered quarks

Abstract

We update our results for $B_K$ obtained using HYP-smeared staggered valence quarks on the MILC asqtad lattices. In the last year, we have added 5 new measurments on the fine ($a\approx 0.09$fm) ensembles, and 2 new measurements on the superfine ($a\approx 0.06$fm) ensembles. These allow a simultaneous extrapolation in $a^2$ and sea quark masses, reducing the corresponding systematic error significantly. Our updated result is ${\hat{B}}_K=0.738\pm 0.005(\text{stat})\pm 0.034(\text{sys})$.

Comments: 7 pages, 4 figures, 2 tables, Lattice 2013 proceeding