A Large-$N$ Phase Transition in a Finite Lattice Gauge Theory

Abstract

We consider gauge theories of non-Abelian $finite$ groups, and discuss the 1+1 dimensional lattice gauge theory of the permutation group $S_N$ as an illustrative example. The partition function at finite $N$ can be written explicitly in a compact form using properties of $S_N$ conjugacy classes. A natural large-$N$ limit exists with a new 't Hooft coupling, $\lambda =g^2\log N$. We identify a Gross-Witten-Wadia-like phase transition at infinite $N$, at $\lambda =2$. It is first order. An analogue of the string tension can be computed from the Wilson loop expectation value, and it jumps from zero to a finite value. We view this as a type of large-$N$ (de-)confinement transition. Our holographic motivations for considering such theories are briefly discussed.

Comments: 9 pp, double column, 1 plot, v2: references and minor comments, PRD version