Kaon Weak Matrix Elements in 2+1 flavor DWF QCD

TL;DR

This paper presents lattice QCD calculations of $K o ext{pi}$ and $K o 0$ weak matrix elements using 2+1 flavor domain wall fermions, aiding understanding of kaon decays and CP violation.

Contribution

First calculation of $ ext{K} o ext{pi}$ and $ ext{K} o 0$ matrix elements in 2+1 flavor DWF QCD with non-perturbative renormalization.

Findings

Matrix elements measured with controlled statistical errors.

Results relevant for $ ext{K} o ext{pi} ext{pi}$ decay analysis.

Non-perturbative renormalization coefficients computed.

Abstract

$K \to \pi$ and $K \to 0$ weak matrix elements of $\Delta S = 1$ operators have been measured in 2+1 flavor domain wall fermion (DWF) QCD on (3 fm)$^3$ lattices with $a^{-1} = 1.73(3)$ GeV. As is well known, using these matrix elements and chiral perturbation theory allows a determination of the $K \to \pi \pi$ matrix elements that enter in the quantitative value for the $\Delta I = 1/2$ rule and $\epsilon^\prime/\epsilon$. Two light dynamical sea quark masses have been used, along with six valence quark masses, with the lightest valence quark mass $\approx 1/10$ the physical strange quark mass. We report our results for lattice matrix elements in the $SU(3)_L \times SU(3)_R$ (27,1), (8,1), and (8,8) representations, paying particular attention to the statistical errors achieved after measurements on 75 configurations. We also report on our calculation of the non-perturbative renormalization coefficients for these $\Delta S=1$ weak operators, using the Rome-Southampton method.