The Kaon B-parameter in Mixed Action Chiral Perturbation Theory

Abstract

We calculate the kaon B-parameter, B_K, 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 one-loop order, taste-symmetry violations in the staggered sea sector only contribute to flavor-disconnected diagrams by generating an O(a^2) 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 B_K by an amount of O(a^2). This term, however, is not strictly due to taste-breaking, and is therefore also present in the expression for B_K for pure G-W lattice fermions. We also present a numerical study of the mixed B_K expression in order to demonstrate that both discretization errors and finite volume effects are small and under control on the MILC improved staggered lattices.

29 pages, 4 figures; Expanded spurion discussion, other discussions clarified, version to appear in PRD

References in corpus (3)

• Staggered Chiral Perturbation Theory and the Fourth-Root Trick
• Observations on staggered fermions at non-zero lattice spacing
• Unquenched determination of the kaon parameter B_K from improved staggered fermions

Cited by in corpus (14)

• Full nonperturbative QCD simulations with 2+1 flavors of improved staggered quarks
• Nucleon Generalized Parton Distributions from Full Lattice QCD
• The Scalar Strange Content of the Nucleon from Lattice QCD
• Light hadron spectroscopy using domain wall valence quarks on an Asqtad sea
• The neutral kaon mixing parameter B_K from unquenched mixed-action lattice QCD
• First Calculation of Hyperon Axial Couplings from Lattice QCD
• Universality of Mixed Action Extrapolation Formulae
• Mixed Meson Masses with Domain-Wall Valence and Staggered Sea Fermions
• Discretization effects and the scalar meson correlator in mixed-action lattice simulations
• SU(2) Low-Energy Constants from Mixed-Action Lattice QCD
• Evidence for non-analytic light quark mass dependence in the baryon spectrum
• Mixed Action Effective Field Theory: an Addendum
• Progress in kaon physics on the lattice
• Bubble contributions to scalar correlators with mixed actions