Kaon B parameter from quenched domain-wall QCD

We report on a calculation of B-K with domain-wall fermion action in quenched QCD. Simulations are made with a renormalization group improved gauge action at beta = 2.6 and 2.9 corresponding to a(-1) approximate to 2 and 3 GeV. Effects, due to finite fifth dimensional size N-5 and finite spatial size N-sigma are examined in detail. Matching to the continuum operator is made perturbatively at one loop order. We obtain B-K(mu = 2 GeV) = 0.5740(61)(191), where the first error is statistical and the second error represents an estimate of scaling violation and O(alpha (2)) errors in the renormalization factor added in quadrature, as an estimate of the continuum value in the modified minimal subtraction ((MS) over bar) scheme with naive dimensional regularization. This value is consistent, albeit somewhat small, with B-K(mu = 2 GeV) = 0.068(42) obtained b the JLQCD Collaboration using the Kogut-Susskind quark action. Results for light quark masses are also reported