Decay of a Massive Particle in a Stiff Matter Dominated Universe

TL;DR

This paper calculates how a massive particle's decay rate is affected by a stiff matter dominated universe, showing that gravity extends particle lifetimes, especially for lighter particles, with implications for cosmology.

Contribution

It provides the first detailed calculation of decay rates of massive particles in a stiff matter universe, highlighting gravitational effects on particle lifetimes.

Findings

Decay rates are reduced compared to flat space.

Particle lifetimes are longer in a stiff matter universe.

Lighter particles experience a greater increase in lifetime.

Abstract

In the presence of a gravitational field decay rates may significantly differ from flat space equivalent. By studying mutually interacting quantum fields the decay rates can be calculated on a given spacetime. This paper presents the calculation of the transition probability for the decay of a massive scalar particle in a stiff matter dominated universe. We find that due to the precence of a gravitational field a finite correction to the transition probability is added which depends inversely on the mass. Moreover the decay rate is smaller and lifetime of the particles is longer compared to flat space. The mass dependence is such that the lifetime of lighter particles is prolonged more compared to heavier particles. This result may be of significance when studying cosmological situations involving stiff matter.