Testing improved staggered fermions with $m_s$ and $B_K$

Abstract

We study the improvement of staggered fermions using hypercubically smeared (HYP) links. We calculate the strange quark mass and the kaon B-parameter, $B_K$, in quenched QCD on a $16^3\times 64$ lattice at $\beta =6.0$. We find $m_s(\overline{\mathrm{MS}},2\mathrm{GeV})=101.2\pm 1.3\pm 4$MeV and $B_K(\overline{\mathrm{MS}},2\mathrm{GeV})=0.578\pm 0.018\pm 0.042$, where the first error is from statistics and fitting, and the second from using one-loop matching factors. The scale ($1/a=1.95$GeV) is set by $M_{\rho }$, and $m_s$ is determined using the kaon mass. Comparing to quenched results obtained using unimproved staggered fermions and other discretizations, we argue that the size of discretization errors in $B_K$ is substantially reduced by improvement.

Comments: 9 pages, 12 figure, referee's comments are incorporated