Brane Cosmology with the Chameleon Scalar Field in Bulk

TL;DR

This paper explores how a chameleon scalar field in the bulk influences universe evolution, leading to early inflation, standard radiation era, and late-time acceleration, with thermodynamic law considerations.

Contribution

It introduces a model with a bulk chameleon scalar field affecting cosmological dynamics, including inflation and late acceleration, and analyzes thermodynamic law validity.

Findings

Scalar field induces exponential inflation in early universe

Effective potential recovers standard equations during inflation

Universe exhibits late-time accelerated expansion

Abstract

In this work we investigate the effect of a kind of scalar field, called chameleon, on the evolution of universe. We put this scalar field in the bulk. It is displayed that this scalar field gives us an exponential expansion in early time which may concern inflation. Interaction between scalar field and matter bring some complications in our analysis, however it is shown that by defining an effective potential, we could recover conventional equation at inflation era. After inflation, and entering the universe in radiation era, the exponential expansion is omitted. Also, in late time the universe possess an accelerated expansion. In the last section, the validity of generalized second law of thermodynamic, with assumption the validity of first law is considered.