Tuesday, August 28, 2012

1208.5325 (Wouter Kager et al.)

The combinatorial approach to the Ising model: foundations and critical
point
   [PDF]

Wouter Kager, Marcin Lis, Ronald Meester
The combinatorial method is a beautiful way to rigorously study the two-dimensional Ising model with no external field. In this paper, we explore the foundations of the method, including all details that have so far been neglected or overlooked in the literature. We also demonstrate how the method can be applied to prove some classical results about the Ising model on the square lattice. This leads to new explicit formulae for the free energy density and two-point functions in terms of sums over loops, valid all the way up to the self-dual point. It follows that the self-dual point is critical both for the behaviour of the free energy density, and for the decay of the two-point functions.
View original: http://arxiv.org/abs/1208.5325

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