The massless S-matrix of integrable σ-models

Abstract In contradistinction to the case of massive excitations, the connection between integrability and the tree-level massless scattering matrix of integrable σ-models is lost. Namely, in well-known 2-d integrable models the tree-level massless S-matrix exhibits particle production and fails to...

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Bibliographic Details
Main Author: George Georgiou
Format: Article
Language:English
Published: SpringerOpen 2025-01-01
Series:Journal of High Energy Physics
Subjects:
Online Access:https://doi.org/10.1007/JHEP01(2025)189
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Summary:Abstract In contradistinction to the case of massive excitations, the connection between integrability and the tree-level massless scattering matrix of integrable σ-models is lost. Namely, in well-known 2-d integrable models the tree-level massless S-matrix exhibits particle production and fails to factorise. This is conjectured to happen due to IR ambiguities in the massless tree-level amplitudes. We present a definition of the massless S-matrix which has all the nice properties of integrable theories, there is no particle production and the S-matrix factorises. Our definition works for the large class of σ-models with one or more isometries. As an example, we present in detail the case of the SU(2) principal chiral model (PCM).
ISSN:1029-8479