On-shell diagrams, Graßmannians and integrability for form factors

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We apply on-shell and integrability methods that have been developed in the context of scattering amplitudes in N=4 (Formula Presented.) SYM theory to tree-level form factors of this theory. Focussing on the colour-ordered super form factors of the chiral part of the stress-tensor multiplet as an example, we show how to systematically construct on-shell diagrams for these form factors with the minimal form factor as further building block in addition to the three-point amplitudes. Moreover, we obtain analytic representations in terms of Graßmannian integrals in spinor helicity, twistor and momentum twistor variables. While Yangian invariance is broken by the operator insertion, we find that the form factors are eigenstates of the integrable spin-chain transfer matrix built from the monodromy matrix that yields the Yangian generators. Constructing them via the method of R operators allows to introduce deformations that preserve the integrable structure. We finally show that the integrable properties extend to minimal tree-level form factors of generic composite operators as well as certain leading singularities of their n-point loop-level form factors.

Original languageEnglish
Article number182
JournalJournal of High Energy Physics
Issue number1
Pages (from-to)1-46
Number of pages46
Publication statusPublished - 1 Jan 2016
Externally publishedYes

    Research areas

  • AdS-CFT Correspondence, Integrable Field Theories, Scattering Amplitudes, Supersymmetric gauge theory

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