Chiral extrapolation beyond the power-counting regime

TL;DR

This paper develops a method to accurately extrapolate the rho meson mass to physical pion mass using quenched lattice QCD data, even outside the traditional chiral power-counting regime, demonstrating predictive capability without prior bias.

Contribution

It introduces an extended effective field theory approach with an optimal regulator for extrapolating hadron masses beyond the chiral power-counting regime using lattice QCD data.

Findings

Successful extrapolation of rho meson mass to the chiral regime

Identification of an optimal regulator from lattice data

Validation of the method with blinded data analysis

Abstract

Chiral effective field theory can provide valuable insight into the chiral physics of hadrons when used in conjunction with non-perturbative schemes such as lattice QCD. In this discourse, the attention is focused on extrapolating the mass of the rho meson to the physical pion mass in quenched QCD (QQCD). With the absence of a known experimental value, this serves to demonstrate the ability of the extrapolation scheme to make predictions without prior bias. By using extended effective field theory developed previously, an extrapolation is performed using quenched lattice QCD data that extends outside the chiral power-counting regime (PCR). The method involves an analysis of the renormalization flow curves of the low energy coefficients in a finite-range regularized effective field theory. The analysis identifies an optimal regulator, which is embedded in the lattice QCD data themselves. This optimal regulator is the regulator value at which the renormalization of the low energy coefficients is approximately independent of the range of quark masses considered. By using recent precision, quenched lattice results, the extrapolation is tested directly by truncating the analysis to a set of points above 380 MeV, while being blinded of the results probing deeply into the chiral regime. The result is a successful extrapolation to the chiral regime.