Perturbative soft graviton theorems in de Sitter spacetime

TL;DR

This paper investigates how soft graviton scattering amplitudes are modified in de Sitter space with a small cosmological constant, revealing universal features similar to those in flat spacetime.

Contribution

It extends Weinberg's soft graviton theorems to de Sitter spacetime using perturbative expansion in the cosmological constant, including leading and subleading corrections.

Findings

Computed corrections to soft graviton amplitudes in de Sitter space.

Identified universal features of soft graviton amplitudes similar to flat spacetime.

Demonstrated the applicability of soft theorems in curved backgrounds.

Abstract

We consider soft graviton scattering for a theory where Einstein's gravity is minimally coupled to a scalar field in the presence of a cosmological constant, i.e. in a background de Sitter space. Employing a perturbative expansion in a small cosmological constant, we compute leading, subleading and sub-subleading corrections to Weinberg's soft graviton amplitude for the tree-level scatterings in the static patch of de Sitter space. We observe similar universal features of the soft graviton amplitude as found in [JHEP10(2023)055] for the soft photons.