A new approach to instanton calculations in the O(3) nonlinear sigma model

Abstract

We construct all instantons in the \nlsig\ on a cylindrical space-time, known not to exist on a finite time interval. The scale parameter, $\rho$, is related to the boundary condition in time. This may cure the $\rho \to 0$ divergent instanton gas, through a proper inclusion of in and out states in the path integral.

Comments: References added and corrected. Contribution to Lattice'94, 27 Sep - 1 Oct 1994, Bielefeld, Germany. 3 pages PostScript, uuencoded compressed