Isospin breaking in octet baryon mass splittings

TL;DR

This paper uses SU(3) flavour symmetry breaking expansion to quantify the QCD contributions to octet baryon mass splittings caused by quark mass differences, demonstrating a highly convergent expansion method.

Contribution

It introduces a method to determine baryon mass splittings from quark mass differences using SU(3) symmetry breaking expansion with computationally efficient simulations.

Findings

Quadratic terms only slightly affect results, indicating rapid convergence.

Mass splittings can be expressed in terms of kaon mass splitting.

Method allows for precise determination of QCD contributions to baryon masses.

Abstract

Using an SU(3) flavour symmetry breaking expansion in the quark mass, we determine the QCD component of the nucleon, Sigma and Xi mass splittings of the baryon octet due to up-down (and strange) quark mass differences in terms of the kaon mass splitting. Provided the average quark mass is kept constant, the expansion coefficients in our procedure can be determined from computationally cheaper simulations with mass degenerate sea quarks and partially quenched valence quarks. Both the linear and quadratic terms in the SU(3) flavour symmetry breaking expansion are considered; it is found that the quadratic terms only change the result by a few percent, indicating that the expansion is highly convergent.