Hadronic Parity Violation from Twisted Mass Lattice QCD

TL;DR

This paper reports an exploratory lattice QCD calculation of the parity-violating pion-nucleon coupling $h_ppa$, using twisted mass fermions and focusing on nucleon matrix elements of effective 4-quark operators.

Contribution

It introduces a novel lattice QCD approach to estimate the parity-violating pion-nucleon coupling using twisted mass fermions and the PCAC relation.

Findings

Initial estimate for $h_ppa$ presented

Techniques for nucleon matrix element determination discussed

Study uses a 260 MeV pion mass ensemble

Abstract

We present results for an exploratory lattice calculation of the leading parity-violating pion-nucleon coupling $h_\pi^1$. Based on the PCAC relation we use a parity-conserving Lagrangian and focus on the techniques to determine the nucleon matrix elements of the effective 4-quark operators. For our study we employ an ensemble of twisted mass fermions with $260$ MeV pion mass. Barring mixing with lower-dimensional operators and renormalization at this stage, we discuss our estimate for $h_\pi^1$.