%0 Journal Article
%T O(n) vector model at n=-1, -2 on random planar lattices: a direct combinatorial derivation
%A Sergio Caracciolo
%A Andrea Sportiello
%J Statistics
%D 2004
%I arXiv
%R 10.1088/1742-5468/2005/02/P02002
%X The O(n) vector model with logarithmic action on a lattice of coordination 3 is related to a gas of self-avoiding loops on the lattice. This formulation allows for analytical continuation in n: critical behaviour is found in the real interval [-2,2]. The solution of the model on random planar lattices, recovered by random matrices, also involves an analytic continuation in the number n of auxiliary matrices. Here we show that, in the two cases n=-1, -2, a combinatorial reformulation of the loop gas problem allows to achieve the random matrix solution with no need of this analytical continuation.
%U http://arxiv.org/abs/cond-mat/0412327v2