Beyond the Standard Model Kaon Mixing with Physical Masses

TL;DR

This paper reports on a lattice QCD calculation of beyond the standard model kaon mixing parameters using physical quark masses, improving accuracy and consistency with previous results.

Contribution

First calculation of BSM kaon mixing matrix elements with physical quark masses, reducing errors and confirming previous findings.

Findings

Results consistent with previous calculations

Reduced statistical and systematic errors

Performed continuum chiral extrapolation

Abstract

We present results from a calculation of beyond the standard model (BSM) kaon mixing including data physical with light quark masses. We simulate $N_f=2+1$ QCD with Iwasaki gauge and domain wall fermion action on 8 ensembles, spanning 3 lattice spacings and pion masses from the physical value up to 430MeV. The ratio of the BSM to standard model (SM) matrix elements are extracted from the correlation functions and renormalised using the RI-SMOM Rome-Southampton method with non-exceptional kinematics. The results at the physical point continuum limit are found by performing a simultaneous continuum chiral extrapolation. In this work we gain consistency with our previous results and achieve a reduction in both the statistical and systematic error.