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Integrable Quantum Field Theories in Finite Volume: Excited State Energies

V. V. Bazhanov·S. L. Lukyanov·A. B. Zamolodchikov
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Abstract

We develop a method of computing the excited state energies in Integrable Quantum Field Theories (IQFT) in finite geometry, with spatial coordinate compactified on a circle of circumference R. The IQFT ``commuting transfer-matrices'' introduced by us (BLZ) for Conformal Field Theories (CFT) are generalized to non-conformal IQFT obtained by perturbing CFT with the operator $Φ_{1,3}$. We study the models in which the fusion relations for these ``transfer-matrices'' truncate and provide closed integral equations which generalize the equations of Thermodynamic Bethe Ansatz to excited states. The explicit calculations are done for the first excited state in the ``Scaling Lee-Yang Model''.

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V. V. Bazhanov, S. L. Lukyanov, A. B. Zamolodchikov. 1996-07-12. Integrable Quantum Field Theories in Finite Volume: Excited State Energies. https://doi.org/10.1016/s0550-3213(97)00022-9

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