KaonBParameter from Quenched Lattice QCD

We present results of a large-scale simulation for the kaon B parameter BK in quenched lattice QCD with the Kogut-Susskind quark action. Calculating BK at 1% statistical accuracy for seven values of lattice spacing in the range a≈0.24--0.04fm on lattices up to 56³×96, we verify the theoretically predicted quadratic a dependence. Strong indications are found that, with our level of accuracy, αMS̄(1/a)² terms arising from our one-loop matching procedure have to be included in the continuum extrapolation. We present BK(NDR,2GeV)0ex0ex=0ex0ex0.628(42) as our final value, where NDR indicates naive dimensional regularization.