Abstract
Matrix elements of Wilson-line dressed operators play a central role in the factorization of soft and collinear modes in gauge theories. When expressed using spinor helicity variables, these so-called form factors admit a classification starting from a Maximally Helicity Violating configuration, in close analogy with gauge theory amplitudes. We show that a single-line complex momentum shift can be used to derive recursion relations that efficiently compute these helicity form factors at tree-level: a combination of lower point form factors and on-shell amplitudes serve as the input building blocks. We obtain novel compact expressions for the 1 → 2 and 1 → 3 splitting functions in QCD, which also serves to validate our methods.
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Acknowledgments
We would like to thank Samuel Abreu, Justin Berman, Henriette Elvang, Pier Monni, and Ian Moult for their invaluable feedback. T. Cohen is supported by the U.S. Department of Energy under grant number DE-SC0011640. The package S@M has been used in this work [108].
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Cohen, T., Riembau, M. Recursion for Wilson-line form factors. J. High Energ. Phys. 2024, 132 (2024). https://doi.org/10.1007/JHEP10(2024)132
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DOI: https://doi.org/10.1007/JHEP10(2024)132