An analysis of the nucleon spectrum from lattice partially-quenched QCD

TL;DR

This paper uses lattice QCD data and chiral perturbation theory to accurately extrapolate the nucleon mass, accounting for discretization, finite volume, and partial quenching effects, and improves the precision of low energy constants.

Contribution

It introduces a comprehensive framework combining finite range regularized chiral perturbation theory with lattice data to improve nucleon mass extrapolation accuracy.

Findings

Extrapolated nucleon mass agrees with experimental values.

Reduced errors in low energy constants compared to previous methods.

Finite volume and discretization effects are well modeled.

Abstract

The chiral extrapolation of the nucleon mass, M_n, is investigated using data coming from 2-flavour partially-quenched lattice simulations. A large sample of lattice results from the CP-PACS Collaboration is analysed using the leading one-loop corrections, with explicit corrections for finite lattice spacing artifacts. The extrapolation is studied using finite range regularised chiral perturbation theory. The analysis also provides a quantitative estimate of the leading finite volume corrections. It is found that the discretisation, finite-volume and partial quenching effects can all be very well described in this framework, producing an extrapolated value of M_n in agreement with experiment. Furthermore, determinations of the low energy constants of the nucleon mass's chiral expansion are in agreement with previous methods, but with significantly reduced errors. This procedure is also compared with extrapolations based on polynomial forms, where the results are less encouraging.