Large-nLimit ofSU(n)Quantum "Spin" Chains

Abstract

A class of $\mathrm{SU}\mathrm{}\left(n\right)\mathrm{}$ antiferromagnetic quantum "spin" chains is solved in the large-$n$ limit. While the low-lying spectrum of the normal spin chain ($n=2\mathrm{}$) consists of massless solitons, in the large-$n$ limit the soliton is massive. Furthermore, the models exhibit many features of the $C{P}^n$ field theories at nonzero topological charge, which, it was recently argued, they become in the limit of a large representation.