Tuning the strange quark mass in lattice simulations

TL;DR

This paper proposes an alternative method for tuning quark masses in lattice QCD simulations by fixing the singlet quark mass, enabling more accurate and flexible extrapolations to physical quark masses.

Contribution

It introduces a novel approach to quark mass tuning in lattice QCD that accounts for different renormalisations and allows a broader exploration of quark mass parameter space.

Findings

Correct order for baryon octet and decuplet spectra

Mass extrapolation within a few percent of experimental values

Method accommodates heavy up-down and light strange quarks

Abstract

QCD lattice simulations with 2+1 flavours typically start at rather large up-down and strange quark masses and extrapolate first the strange quark mass to its physical value and then the up-down quark mass. An alternative method of tuning the quark masses is discussed here in which the singlet quark mass is kept fixed, which ensures that the kaon always has mass less than the physical kaon mass. It can also take into account the different renormalisations (for singlet and non-singlet quark masses) occurring for non-chirally invariant lattice fermions and so allows a smooth extrapolation to the physical quark masses. This procedure enables a wide range of quark masses to be probed, including the case with a heavy up-down quark mass and light strange quark mass. Results show the correct order for the baryon octet and decuplet spectrum and an extrapolation to the physical pion mass gives mass values to within a few percent of their experimental values.