Vacuum fluctuation in a 4D spacetime due an evolving non-compact extra-dimension

TL;DR

This paper explores how vacuum fluctuations in a 4D spacetime are influenced by an evolving non-compact extra dimension in 5D cosmological models, highlighting particle creation and mode behavior during expansion.

Contribution

It demonstrates the possibility of particle creation in static 4D spacetime embedded in an expanding 5D bulk and analyzes the impact of expansion parameters on physical quantities.

Findings

Particle creation can occur in static 4D spacetime with an expanding extra dimension.

Expansion rate parameters ({},{\u00df}) govern vacuum-related physical quantities.

Massive modes with ky=0 are confined and only allowed in the model.

Abstract

The regime of exponentially fast expansion in 5D cosmological models was investigated. Many limit cases was also studied. It was shown that there is a possibility to particle creation in a static 4D spacetime if it embedded in an bulk with an expanding extra-dimension y. It was also shown that many physical quantities like the particle number density, vacuum pressure and energy density has its behavior governed by the expansion rate parameters ({\alpha},{\beta}) that control the inflation process. These parameters also limit the field modes that can be created in a given model. The case with modes with ky = 0 was investigated and was shown that only massive modes are allowed. These modes are taken to be confined in the 4D spacetime. From the 5D Einstein's field equation, where the only sources considered comes from the vacuum fluctuation, was determined the presence of a given cosmological time ({\eta}) that makes the 5D cosmological constant vanish in some models and behave like a limit time that governs a transition from an expanding cosmological model to a completely static model.