Brane singularities with mixtures in the bulk

TL;DR

This paper analyzes the singularity structures and asymptotic behaviors of five-dimensional braneworld models with a bulk mixture of a perfect fluid and a scalar field, revealing conditions for singularity avoidance.

Contribution

It extends previous work by systematically studying the effects of a bulk scalar field and fluid mixture on brane singularities and asymptotic solutions.

Findings

Flat brane solutions can avoid finite-distance singularities.

Singularity avoidance occurs within specific interaction parameter ranges.

Results generalize previous models without scalar fields.

Abstract

By extending previous analysis of the authors, a systematic study of the singularity structure and possible asymptotic behaviors of five-dimensional braneworld solutions is performed in the case where the bulk is a mixture of an analog of perfect fluid (with a density and pressure depending on the extra coordinate) and a massless scalar field. The two bulk components interact by exchanging energy so that the total energy is conserved. In a particular range of the interaction parameters, we find flat brane general solutions avoiding the singularity at finite distance from the brane, in the same region of the equation of state constant parameter $\gamma=P/\rho$ that we found previously in the absence of the bulk scalar field $(-1<\gamma<-1/2)$.