Extraction of K-->pipi Matrix Elements with Wilson Fermions

TL;DR

This paper reports on a lattice QCD calculation of K to pi pi matrix elements using Wilson fermions, addressing finite volume effects, renormalization issues, and preliminary results for specific isospin channels.

Contribution

It introduces a method to avoid Goldstone pole contamination in renormalization constants for delta I=3/2 operators and presents initial results for delta I=1/2 matrix elements.

Findings

Finite volume energy shifts studied for I=0 and I=2 channels.

Method to mitigate Goldstone pole contamination explained.

Preliminary matrix element results for delta I=1/2 operators shown.

Abstract

We present the status of a lattice calculation for the K-->pipi matrix elements of the (delta S=1) effective weak Hamiltonian, directly with two pion in the final state. We study the energy shift of two pion in a finite volume both in the I=0 and I=2 channels. We explain a method to avoid the Goldstone pole contamination in the computation of renormalization constants for (delta I=3/2) operators. Finally we show some preliminary results for the matrix elements of (delta I=1/2) operators. Our quenched simulation is done at beta=6.0, with Wilson fermions, on a (24^3 X 64) lattice.