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arXiv · 2005.08981

Soft Matters, or the Recursions with Massive Spinors

Adam Falkowski·Camila S. Machado
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Abstract

We discuss recursion relations for scattering amplitudes with massive particles of any spin. They are derived via a two-parameter shift of momenta, combining a BCFW-type spinor shift with the soft limit of a massless particle involved in the process. The technical innovation is that spinors corresponding to massive momenta are also shifted. Our recursions lead to a reformulation of the soft theorems. The well-known Weinberg's soft factors are recovered and, in addition, the subleading factors appear reshaped such that they are directly applicable to massive amplitudes in the modern on-shell language. Moreover, we obtain new results in the context of non-minimal interactions of massive matter with photons and gravitons. These soft theorems are employed for practical calculations of Compton and higher-point scattering. As a by-product, we introduce a convenient representation of the Compton scattering amplitude for any mass and spin.

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Adam Falkowski, Camila S. Machado. 2020-05-18. Soft Matters, or the Recursions with Massive Spinors. https://doi.org/10.1007/jhep05(2021)238

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