Extending the Utility of Partially Quenched QCD

TL;DR

This paper discusses the complications introduced by partial quenching in lattice QCD and proposes methods to determine the associated low-energy constants, including calculations of meson properties and corrections for improved lattice data analysis.

Contribution

It identifies a new four-derivative operator in partially quenched chiral perturbation theory and provides a framework to determine its coefficient through scattering processes and meson property calculations.

Findings

Identified a new four-derivative operator due to partial quenching.

Calculated one-loop contributions to meson masses and decay constants.

Presented NNLO corrections for lattice QCD data fitting.

Abstract

It has been proposed that partially quenched chiral perturbation theory can be used together with partially quenched lattice QCD to determine the low-energy constants of real QCD. We point out a complication of this approach and show how it can be resolved. Partial quenching changes the chiral symmetry group and introduces a new independent four-derivative operator. We explore the effects of this new operator. We describe tree-level scattering processes to which it contributes, and show how they can be used, in principle, to deterimine its unknown coefficient. We also calculate its lowest-order (one-loop) contribution to charged meson masses and decay constants. In addition, we present the form of the analytic next-to-next-to-leading order meson mass and decay constant corrections, which are needed for lattice fits.