Enhanced Soft Limits in de Sitter Space

TL;DR

This paper extends the concept of enhanced soft limits from flat space to de Sitter space, showing how boundary conformal symmetry and bootstrap methods can determine scalar interactions and couplings, with implications for the double copy.

Contribution

It demonstrates that enhanced soft limits in de Sitter space can be used to fix scalar couplings and masses, extending symmetry-based constraints to curved spacetime.

Findings

Enhanced soft limits fix masses and four-point couplings in de Sitter.

Boundary conformal generators relate wavefunction coefficients to contact diagrams.

Bootstrap at six points illustrates fixing higher-point couplings.

Abstract

In flat space, the scattering amplitudes of certain scalar effective field theories exhibit enhanced soft limits due to the presence of hidden symmetries. In this paper, we show that this phenomenon extends to wavefunction coefficients in de Sitter space. Using a representation in terms of boundary conformal generators acting on contact diagrams, we find that imposing enhanced soft limits fixes the masses and four-point couplings (including curvature corrections) in agreement with Lagrangians recently derived from hidden symmetries. Higher-point couplings can then be fixed using a bootstrap procedure which we illustrate at six points. We also discuss implications for the double copy in de Sitter space.