Improved actions for the two-dimensional sigma-model

Abstract

For the O(N) sigma-model we studied the improvement program for actions with two- and four-spin interactions. An interesting example is an action which is reflection-positive, on-shell improved, and has all the coupling defined on an elementary plaquette. We show the large N solution and preliminary Monte Carlo results for N=3.

Comments: Talk presented at Lattice '97 (Improvement and Renormalisation), Edinburgh (UK), July 1997. LaTeX2e, 3 pages, 2 figures, uses espcrc2 and epsfig