Annihilation of the scalar pair into a photon on de Sitter spacetime

TL;DR

This paper investigates the annihilation of scalar particle pairs into photons in de Sitter spacetime, revealing that the process's probability depends on the mass to expansion ratio and vanishes in flat spacetime.

Contribution

It provides an exact calculation of the annihilation process in de Sitter space, highlighting the influence of gravitational expansion on particle interactions.

Findings

Probability depends on mass/expansion ratio

Significant in strong gravitational fields

Vanishes in Minkowski limit

Abstract

The annihilation of massive scalar particles in one photon on de Sitter expanding universe is studied, using perturbation theory. The amplitude and probability corresponding to this process is computed using the exact solutions of the Klein-Gordon and Maxwell equations on de Sitter geometry. Our results show that the expression of the total probability of photon emission is a function dependent on the ratio mass/expansion\, factor. We perform a graphical study of the total probability in terms of the parameter mass/expansion factor, showing that this effect is significant only in strong gravitational fields. We also obtain that the total probability for this process vanishes in the Minkowski limit.