We calculate the kaon B-parameter, BK, in chiral perturbation theory for a partially quenched, mixed-action theory with Ginsparg-Wilson valence quarks and staggered sea quarks. We find that the resulting expression is similar to that in the continuum, and in fact has only two additional unknown parameters. At 1-loop order, taste-symmetry violations in the staggered sea sector only contribute to flavor-disconnected diagrams by generating an O(a2) shift to the masses of taste-singlet sea-sea mesons. Lattice discretization errors also give rise to an analytic term which shifts the tree-level value of BK by an amount of O(a2). This term, however, is not strictly due to taste breaking, and is therefore also present in the expression for BK for pure Ginsparg-Wilson lattice fermions. We also present a numerical study of the mixed BK expression in order to demonstrate that both discretization errors and finite volume effects are small and under control on the MILC improved staggered lattices.
|Original language||English (US)|
|Journal||Physical Review D - Particles, Fields, Gravitation and Cosmology|
|State||Published - Feb 5 2007|
ASJC Scopus subject areas
- Nuclear and High Energy Physics
- Physics and Astronomy (miscellaneous)