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Integrable quantum field theory with boundaries: The exact g-function

Dorey, Patrick; Fioravanti, Davide; Rim, Chaiho; Tateo, Roberto

Integrable quantum field theory with boundaries: The exact g-function Thumbnail


Davide Fioravanti

Chaiho Rim

Roberto Tateo


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.


Dorey, P., Fioravanti, D., Rim, C., & Tateo, R. (2004). Integrable quantum field theory with boundaries: The exact g-function. Nuclear Physics B, 696(3), 445-467.

Journal Article Type Article
Publication Date Sep 27, 2004
Deposit Date Feb 26, 2008
Publicly Available Date Apr 27, 2009
Journal Nuclear Physics B
Print ISSN 0550-3213
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 696
Issue 3
Pages 445-467
Keywords Boundary problems, Conformal field theory, Integrability, Thermodynamic Bethe ansatz.


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