Tunneling Through Sphalerons: The O(3) Sigma-Model on a Cylinder

Abstract

We construct all instantons for the \nlsig\ on a cylinder, known not to exist on a finite time interval. We show that the widest instantons go through sphalerons. A re-interpretation of moduli-space transforms the scale parameter $\rho$ to a boundary condition in time. This may give a handle on the $\rho \to 0$ divergent instanton gas.

Comments: 10 pages, LaTeX, 1 figure appended (uuencoded), Leiden preprint INLO-PUB-5/94