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Sigma models as perturbed conformal field theories

Paul Fendley
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Abstract

We show that two-dimensional sigma models are equivalent to certain perturbed conformal field theories. When the fields in the sigma model take values in a space G/H for a group G and a maximal subgroup H, the corresponding conformal field theory is the $k\to\infty$ limit of the coset model $(G/H)_k$, and the perturbation is related to the current of G. This correspondence allows us for example to find the free energy for the "O(n)" (=O(n)/O(n-1)) sigma model at non-zero temperature. It also results in a new approach to the CP^{n} model.

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Paul Fendley. 2001-06-07. Sigma models as perturbed conformal field theories. https://doi.org/10.1103/physrevlett.83.4468

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