Baryon Magnetic Moments in Alternate 1/N_c Expansions

TL;DR

This paper demonstrates that baryon magnetic moments favor the color-fundamental 1/N_c expansion over the two-index antisymmetric representation, providing experimental evidence for the preferred large N_c expansion in QCD.

Contribution

It provides the first experimental evidence that baryon magnetic moments support the color-fundamental 1/N_c expansion over alternative large N_c expansions.

Findings

Magnetic moments favor the color-fundamental 1/N_c expansion

Experimental data distinguishes among different 1/N_c expansions

Supports the specific large N_c expansion as the correct description

Abstract

Recent work shows not only the necessity of a 1/N_c expansion to explain the observed mass spectrum of the lightest baryons, but also that at least two distinct large N_c expansions, in which quarks transform under either the color fundamental or the two-index antisymmetric representation of SU(N_c), work comparably well. Here we show that the baryon magnetic moments do not support this ambivalence; they strongly prefer the color-fundamental 1/N_c expansion, providing experimental evidence that nature decisively distinguishes among 1/N_c expansions for this observable.