The Kaon B-Parameter in Staggered Chiral Perturbation Theory

TL;DR

This paper computes the kaon B-parameter using staggered chiral perturbation theory at next-to-leading order, accounting for taste-breaking effects and perturbative matching, to improve lattice QCD extrapolations.

Contribution

It extends staggered chiral perturbation theory to include perturbative matching effects and taste-breaking, providing a more accurate framework for B_K calculations.

Findings

Inclusion of perturbative matching factors affects B_K calculations.

Taste-breaking effects are incorporated through O(a^2) terms and operator mixing.

Results facilitate improved chiral and continuum extrapolations in lattice QCD.

Abstract

We calculate the kaon B-parameter, B_K, to next-to-leading order in staggered chiral perturbation theory. We extend the usual power counting to include the effects of using perturbative (rather than non-perturbative) matching factors. Taste breaking enters through the O(a^2) terms in the effective action, through mixing with higher-dimension operators, and through the truncation of matching factors. These effects cause mixing with several additional operators, complicating the chiral and continuum extrapolations. We summarize the results here; all details can be found in hep-lat/0507012.