CP(N−1)model on a disk and decay of a non-Abelian string

Abstract

We consider the role of quantum effects in the nonperturbative decay of the non-Abelian string with orientational moduli in nonsupersymmetric $D=4$ gauge theory. To this aim the effective action in the $CP(N\ensuremath{-}1)$ model on a disk at large $N$ has been calculated. It exhibits a phase transition at some radius, the ``wrong sign'' Luscher term, and a large boundary boojumlike negative contribution. The effect of the $\ensuremath{\theta}$ term and the possibility of the spontaneous creation of the non-Abelian string are briefly discussed.