Octet Baryon Magnetic Moments from Lattice QCD: Approaching Experiment from a Three-Flavor Symmetric Point

TL;DR

This study uses lattice QCD to compute octet baryon magnetic moments at physical and unphysical quark masses, revealing patterns linked to quark models and testing large-Nc relations, with implications for strange matter stability.

Contribution

It provides the first lattice QCD determination of octet baryon magnetic moments across different quark masses and examines their relation to quark models and large-Nc QCD predictions.

Findings

Magnetic moments show mild pion-mass dependence in magneton units.

Large-Nc relations are less accurate than quark model predictions.

First extraction of isovector transition magnetic polarizability.

Abstract

Lattice QCD calculations with background magnetic fields are used to determine the magnetic moments of the octet baryons. Computations are performed at the physical value of the strange quark mass, and two values of the light quark mass, one corresponding to the three-flavor symmetric point, where the pion mass is 800 MeV, and the other corresponding to a pion mass of 450 MeV. The moments are found to exhibit only mild pion-mass dependence when expressed in terms of appropriately chosen magneton units- the natural baryon magneton. A curious pattern is revealed among the anomalous baryon magnetic moments which is linked to the constituent quark model, however, careful scrutiny exposes additional features. Relations expected to hold in the large-Nc limit of QCD are studied; and, in one case, a clear preference for the quark model over the large-Nc prediction is found. The magnetically coupled Lambda-Sigma system is treated in detail at the three-flavor symmetric point, with the lattice QCD results comparing favorably with predictions based on SU(3)F symmetry. This analysis enables the first extraction of the isovector transition magnetic polarizability. The possibility that large magnetic fields stabilize strange matter is explored, but such a scenario is found to be unlikely.