Nucleon sigma terms for 2+1 quark flavours

TL;DR

This paper uses lattice QCD simulations with 2+1 flavors to determine nucleon sigma terms by analyzing how hadron masses change with quark masses, providing new estimates for light and strange sigma terms.

Contribution

It introduces a method to extract sigma terms from constrained fits of hadron masses along specific quark mass trajectories in lattice QCD.

Findings

Derived relations between light and strange sigma terms.

Estimated sigma terms for the baryon octet.

Demonstrated the effectiveness of constrained fits in sigma term extraction.

Abstract

QCD lattice simulations yield hadron masses as functions of the quark masses. From the gradients of the hadron masses the sigma terms can then be determined. We consider here dynamical 2+1 flavour simulations, in which we start from a point of the flavour symmetric line and then keep the singlet or average quark mass fixed as we approach the physical point. This leads to highly constrained fits for hadron masses in a multiplet. The gradient of this path for a hadron mass then gives a relation between the light and strange sigma terms. A further relation can be found from the change in the singlet quark mass along the flavour symmetric line. This enables light and strange sigma terms to be estimated for the baryon octet.