The Chiral Extrapolation of Strange Matrix Elements in the Nucleon

TL;DR

This paper investigates how to accurately extrapolate strange quark matrix elements in nucleons from lattice QCD simulations with unphysical up and down quark masses using two-flavor chiral perturbation theory.

Contribution

It demonstrates the use of two-flavor chiral perturbation theory to perform chiral extrapolations of strange matrix elements, avoiding slow convergence issues of three-flavor expansions.

Findings

Chiral expansion of strange matrix elements is feasible with two-flavor chiral perturbation theory.

The approach helps in connecting lattice results at unphysical quark masses to physical values.

Partial-quenched chiral perturbation theory extends the analysis to more general lattice setups.

Abstract

In current lattice simulations of nucleon properties, the up and down quark masses are significantly larger than their physical values, while the strange quark can be included in simulations with its physical mass. When the up and down quark masses are much smaller than the strange-quark mass the chiral extrapolation of strange-quark matrix elements in the nucleon from the lattice up and down quark masses to their physical values can be performed with two-flavor chiral perturbation theory, thereby avoiding the slow convergence problem of the three-flavor chiral expansion. We explore the chiral expansion of several matrix elements of strange operators in the nucleon in two-flavor chiral perturbation theory and two-flavor partial-quenched chiral perturbation theory.