Cosmological Solutions on Compactified AdS_5 with a Thermal Bulk

TL;DR

This paper explores how a thermal bulk fluid influences the dynamics of brane world models in AdS_5, providing exact and perturbative solutions, and analyzing the effects of bulk mass and stabilization on the radion and weak scale.

Contribution

It introduces new exact and perturbative solutions for thermal bulk fluids in AdS_5 brane models, highlighting the role of bulk mass and stabilization potentials.

Findings

Bulk fluid effects are controlled by bulk mass.

Without stabilization, no physical solutions exist for thermal bulk fluids.

Including a stabilizing potential affects radion and weak scale dynamics.

Abstract

This paper is an investigation of the effects of a thermal bulk fluid in brane world models compactified on AdS_5. Our primary purpose is to study how such a fluid changes the bulk dynamics and to compare these effects with those generated by matter localized to the branes. We find an exact cosmological solution for a thermally excited massless bulk field, as well as perturbative solutions with matter on the brane and in the bulk. We then perturb around these solutions to find solutions for a massive bulk mode in the limit where the bulk mass (m_B) is small compared to the AdS curvature scale and T< m_B. We find that without a stabilizing potential there are no physical solutions for a thermal bulk fluid. We then include a stabilizing potential and calculate the shift in the radion as well as the time dependence of the weak scale as a function of the bulk mass. It is shown that, as opposed to a brane fluid, the bulk fluid contribution to the bulk dynamics is controlled by the bulk mass.