Critical exponents and unusual properties of the broken phase in the 3d-RP(2) antiferromagnetic model

We present the results of a Monte Carlo simulation of the antiferromagnetic RP(2) model in three dimensions. With finite-size scaling techniques we accurately measure the critical exponents and compare them with those of O(N) models. We are able to parameterize the corrections-to-scaling. The symmetry properties of the broken phase are also studied.Comment: 4 pages, TeX type, Poster session contribution to "Lattice96" conference, Washington University, StLoui

Antiferromagnetism in four dimensions: search for non-triviality

We present antiferromagnetism as a mechanism capable of modifying substantially the phase diagram and the critical behaviour of statistical mechanical models. This is particularly relevant in four dimensions, due to the connection between second order transition points and the continuum limit as a quantum field theory. We study three models with an antiferromagnetic interaction: the Ising and the O(4) Models with a second neighbour negative coupling, and the \RP{2} Model. Different conclusions are obtained depending on the model.Comment: 4 pages LateX. Contribution to Lat9

Instanton-like Contributions to the Dynamics of Yang-Mills Fields on the Twisted Torus

We study $SU(2)$ lattice gauge theory in small volumes and with twist $\vec{m}=(1,1,1)$. We investigate the presence of the periodic instantons of $Q=\frac{1}{2}$ and determine their free energy and their contribution to the splitting of energy flux sectors \mbox{$E(\vec{e}=(1,1,1))-E(\vec{e}=(0,0,0))$.}Comment: 17 text pages + 1 Table + 3 postscript figures, report# FTUAM/92-3