STRING THEORETICAL INTERPRETATION FOR FINITE N YANG–MILLS THEORY IN TWO DIMENSIONS

Abstract

We discuss the equivalence between a string theory and the two-dimensional Yang–Mills theory with SU (N) gauge group for finite N. We find a sector which can be interpreted as a sum of covering maps from closed string worldsheets to the target space, whose covering number is less than N. This gives an asymptotic expansion of 1/N whose large N limit becomes the chiral sector defined by Gross and Taylor. We also discuss that the residual part of the partition function provides the nonperturbative corrections to the perturbative expansion.