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Integrable quantum field theory with boundaries : the exact g-function.

Dorey, P. and Fioravanti, D. and Rim, C. and Tateo, R. (2004) 'Integrable quantum field theory with boundaries : the exact g-function.', Nuclear physics B., 696 (3). pp. 445-467.


The g-function was introduced by Affleck and Ludwig in the context of critical quantum systems with boundaries. In the framework of the thermodynamic Bethe ansatz (TBA) method for relativistic scattering theories, all attempts to write an exact integral equation for the off-critical version of this quantity have, up to now, been unsuccessful. We tackle this problem by using an n-particle cluster expansion, close in spirit to form-factor calculations of correlators on the plane. The leading contribution already disagrees with all previous proposals, but a study of this and subsequent terms allows us to deduce an exact infrared expansion for g, written purely in terms of TBA pseudoenergies. Although we only treat the thermally-perturbed Ising and the scaling Lee–Yang models in detail, we propose a general formula for g which should be valid for any model with entirely diagonal scattering.

Item Type:Article
Keywords:Boundary problems, Conformal field theory, Integrability, Thermodynamic Bethe ansatz.
Full text:(AM) Accepted Manuscript
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Date accepted:No date available
Date deposited:27 April 2009
Date of first online publication:September 2004
Date first made open access:No date available

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