paper

A study of integrable form factors in massless relativistic

arXiv:2302.08491 · doi:10.1007/JHEP06(2023)005

Abstract

In this paper we initiate the study of form factors for the massless scattering of integrable superstrings, where the difference-form of the -matrix can be exploited to implement the relativistic form factor bootstrap. The non-standard nature of the -matrix implies that traditional methods do not apply. We use the fact that the massless -matrix is a limit of a better-behaved -matrix found by Fendley. We show that the previously conjectured massless dressing factor coincides with the limit of the De Martino - Moriconi improved dressing factor for the Fendley -matrix. After finding a method to construct integral representations of relativistic dressing factors satisfying specific assumptions, we obtain analytic proofs of crossing and unitarity relations and propose a solution to the form factors constraints in the two-particle case.

25 pages, 12 figures. V2: comments and references added, matches published version. V3: error corrected and comments added

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