Radiation back reaction on moving branes

TL;DR

This paper investigates the effects of radiation back reaction on moving cosmological branes, providing a framework for scalar field interactions in various extra-dimensional settings and deriving bounds related to dark radiation and vacuum energy.

Contribution

It introduces a general framework for analyzing radiation back reaction on branes with different scalar fields and extra-dimensional geometries, including anti-de Sitter spaces.

Findings

Back reaction terms are non-analytic for massless scalar radiation.

Nucleosynthesis bounds impose a lower limit on the string vacuum energy scale.

Equations of motion are solved in simplified scenarios.

Abstract

This paper addresses the radiation back reaction problem for cosmological branes. A general framework is provided in which results are given for the radiation reaction with massles and massive scalar fields with flat extra dimensions and massless conformal fields in anti-de Sitter extra dimensions. For massless scalar field radiation the back reaction terms in the equation of motion are non-analytic. The interpretation of the radiation reaction terms is discussed and the equations of motion solved in simple cases. Nucleosynthesis bounds on dark radiation give a lower bound on the string vacuum energy scale of $\sqrt{A_T} m_p$, where $A_T$ is the tensor perturbation amplitude in the cosmic microwave background.