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Massless Flows II: the exact S-matrix approach

P. Fendley·H. Saleur·Al. B. Zamolodchikov
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Abstract

We study the spectrum, the massless S-matrices and the ground-state energy of the flows between successive minimal models of conformal field theory, and within the sine-Gordon model with imaginary coefficient of the cosine term (related to the minimal models by ``truncation''). For the minimal models, we find exact S-matrices which describe the scattering of massless kinks, and show using the thermodynamic Bethe ansatz that the resulting non-perturbative c-function (defined by the Casimir energy on a cylinder) flows appropriately between the two theories, as conjectured earlier. For the non-unitary sine-Gordon model, we find unusual behavior. For the range of couplings we can study analytically, the natural S-matrix deduced from the minimal one by ``undoing'' the quantum-group truncation does not reproduce the proper c-function with the TBA. It does, however, describe the correct properties of the model in a magnetic field.

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P. Fendley, H. Saleur, Al. B. Zamolodchikov. 1993-04-13. Massless Flows II: the exact S-matrix approach. https://doi.org/10.1142/s0217751x93002277

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