paper

First-Order Phase Transition in Potts Models with finite-range interactions

arXiv:math-ph/0609051 · doi:10.1007/s10955-006-9230-8

Abstract

We consider the -state Potts model on , , , with Kac ferromagnetic interactions and scaling parameter $\ga$. We prove the existence of a first order phase transition for large but finite potential ranges. More precisely we prove that for $\ga$ small enough there is a value of the temperature at which coexist Gibbs states. The proof is obtained by a perturbation around mean-field using Pirogov-Sinai theory. The result is valid in particular for , Q=3, in contrast with the case of nearest-neighbor interactions for which available results indicate a second order phase transition. Putting both results together provides an example of a system which undergoes a transition from second to first order phase transition by changing only the finite range of the interaction.

Soumis pour publication a Journal of statistical physics - version révisée

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