Baryon Magnetic Moments in Alternate 1/N_c Expansions

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.

Comments: 18 pages, ReVTeX