Nonlinear (Super)Symmetries and Amplitudes

TL;DR

This paper explores how nonlinear symmetries in theories like supergravity and D3 branes constrain scattering amplitudes, revealing universal behaviors in soft limits and implications for UV completions.

Contribution

It provides a universal derivation of amplitude vanishing in single-soft limits and explains the role of double-soft limits in probing coset space algebra, extending understanding of nonlinear symmetries.

Findings

Universal derivation of vanishing amplitudes in single-soft limits

Double-soft limit probes coset space algebra

Identities describing multiple-soft limits

Abstract

There is an increasing interest in nonlinear supersymmetries in cosmological model building. Independently, elegant expressions for the all-tree amplitudes in models with nonlinear symmetries, like D3 brane Dirac-Born-Infeld-Volkov-Akulov theory, were recently discovered. Using the generalized background field method we show how, in general, nonlinear symmetries of the action, bosonic and fermionic, constrain amplitudes beyond soft limits. The same identities control, for example, bosonic E_{7(7)} scalar sector symmetries as well as the fermionic goldstino symmetries. We present a universal derivation of the vanishing amplitudes in the single (bosonic or fermionic) soft limit. We explain why, universally, the double-soft limit probes the coset space algebra. We also provide identities describing the multiple-soft limit. We discuss loop corrections to N\geq 5 supergravity, to the D3 brane, and the UV completion of constrained multiplets in string theory.