Rotation Operator vs Particle Creation in a Curved Space Time

TL;DR

This paper investigates how the inclusion of rotation operators affects particle creation and entropy calculations for a scalar field in curved spacetime, revealing that particle number is conserved without rotation but entropy can be derived with rotation.

Contribution

It demonstrates the impact of rotation operators on particle creation and entropy in a scalar field within a Robertson-Walker spacetime, highlighting differences in theoretical approaches.

Findings

Particle number remains conserved without rotation operator.

Entropy can be expressed as the logarithm of created particles when rotation is considered.

Using Bogoliubov transformations without rotation preserves initial and final states.

Abstract

Taking into account a neutral massive scalar field minimally coupled to gravity, in a Robertson-Walker metric, it is shown that when the final state is connected with the initial one by means of a Bogoliubov transformation, which does not include the single-mode rotation operator, the mean value of created particles is conserved. When the rotation operator is considered, it is still possible to use the approach of single-mode squeezed operators and get the entropy as the logarithm of the created particles.