We present a new method for determining K --> pi pi matrix elements from lattice simulations that is less costly than direct simulations of K --> pi pi at physical kinematics. It improves, however, upon the traditional "indirect'' approach of constructing the K --> pi pi matrix elements using NLO SU(3) ChPT, which can lead to large higher-order chiral corrections. Using the explicit example of the Delta I =3/2 (27,1) operator to illustrate the method, we obtain a value for Re(A_2) that agrees with experiment and has a total uncertainty of ~20%. Although our simulations use domain-wall valence quarks on the MILC asqtad-improved gauge configurations, this method is more general and can be applied to calculations with any fermion formulation.
@article{arxiv.1011.4524,
title = {K --> pi pi matrix elements from mixed action lattice QCD},
author = {Jack Laiho and Ruth S. Van de Water},
journal= {arXiv preprint arXiv:1011.4524},
year = {2011}
}
Comments
7 pages, 4 figures. Presented at Lattice 2010, June 14-19, 2010, Villasimius, Italy