Universality class of the Nishimori point in the 2D +/- J random-bond Ising model.
We study the universality class of the Nishimori point in the 2D +/- J random-bond Ising model by means of the numerical transfer-matrix method. Using the domain-wall free energy, we locate the position of the fixed point along the Nishimori line at the critical concentration value p(c) = 0.1094 +/- 0.0002 and estimate nu = 1.33 +/- 0.03. Then, we obtain the exponents for the moments of the spin-spin correlation functions as well as the value for the central charge c = 0.464 +/- 0.004. The main qualitative result is the fact that percolation is now excluded as a candidate for describing the universality class of this fixed point.
Honecker
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Institut für Theoretische Physik, TU Braunschweig, Mendelssohnstrasse 3, 38106 Braunschweig, Germany.
Picco
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Pujol
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