Inflation and late time acceleration in braneworld cosmological models with varying brane tension

TL;DR

This paper explores how variable brane tension in braneworld models can drive inflation and late-time acceleration, acting as dark energy, and examines the thermodynamic and observational implications of such models.

Contribution

It introduces a thermodynamic interpretation of variable brane tension models and analyzes their impact on cosmic evolution, including inflation and acceleration phases.

Findings

Initial inflationary expansion driven by brane tension.

Transition to a late-time accelerated de Sitter phase.

Generation of matter through brane tension variation.

Abstract

Braneworld models with variable brane tension $\lambda $ introduce a new degree of freedom that allows for evolving gravitational and cosmological constants, the latter being a natural candidate for dark energy. We consider a thermodynamic interpretation of the varying brane tension models, by showing that the field equations with variable $\lambda $ can be interpreted as describing matter creation in a cosmological framework. The particle creation rate is determined by the variation rate of the brane tension, as well as by the brane-bulk energy-matter transfer rate. We investigate the effect of a variable brane tension on the cosmological evolution of the Universe, in the framework of a particular model in which the brane tension is an exponentially dependent function of the scale factor. The resulting cosmology shows the presence of an initial inflationary expansion, followed by a decelerating phase, and by a smooth transition towards a late accelerated de Sitter type expansion. The varying brane tension is also responsible for the generation of the matter in the Universe (reheating period). The physical constraints on the model parameters, resulted from the observational cosmological data, are also investigated.