New Universality Class in three dimensions: the Antiferromagnetic $R{P}^2$ model

Abstract

We present the results of a Monte Carlo simulation of the $R{P}^2$ model in three dimensions with negative coupling. We observe a second order phase transition between the disordered phase and an antiferromagnetic, unfrustrated, ordered one. We measure, with a Finite Size Scaling analysis, the thermal exponent, obtaining $\nu =0.784(8)$. We have found two magnetic-type relevant operators whose related $\eta$ exponents are $0.038(2)$ and $1.338(8)$ respectively.

Comments: 10 pages, 2 Postscript figures. Revised version: references added