Talk presented by Hiroaki Arisue

Parallel Session: Spin Models I

Thursday July 1st, 14.50 - 15.10, Room B

Large-q expansion of the correlation length in the two-dimensional q-state Potts model

Abstract: We have calculated the large-q expansion of the second moment correlation length for the two dimensional q-state Potts model at the first order phase transition point both in the ordered and disordered phases. The analysis of the obtained series indicates that the asymptotic behavior of the second moment correlation length for $q \rightarrow 4$ in each phase is the same as that of the exactly known true correlation length (defined by the decay rate of the correlation function) in the disordered phase and it enables us to give very precise numerical values of the second moment correlation length for each $q(>4)$. The second moment correlation lengths for the ordered phase and the disordered phase are the same with each other in the large $q$ limit, since the first three terms of the expansion series coincide with each other, and their evaluated numerical difference is at most 7 percent for $q \rightarrow 4$.

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