Paper (*cross-listing*): hep-th/0603223
Date: Wed, 29 Mar 2006 16:36:18 GMT (292kb)

Title: Semi-transparent brane-worlds

Authors: Zolt\'an Keresztes, Ibolya K\'ep\'{\i}r\'o, L\'aszl\'o \'A. Gergely

Comments: 15 pages, 8 figures
\\
We study the evolution of a closed Friedmann brane perturbed by the Hawking
radiation escaping a bulk black hole. The semi-transparent brane absorbes some
of the infalling radiation, the rest being transmitted across the brane to the
other bulk region. We characterize the cosmological evolution in terms of the
transmission rate $\epsilon$. For small values of $\epsilon $ a critical-like
behaviour could be observed, when the acceleration due to radiation pressure
and the deceleration induced by the increasing self-gravity of the brane
roughly compensate each other, and cosmological evolution is approximately the
same as without radiation. Lighter (heavier) branes than those with the
critical energy density will recollapse slower (faster). This feature is
obstructed at high values of $\epsilon $, where the overall effect of the
radiation is to speed-up the recollapse. We determine the maximal value of the
transmission rate for which the critical-like behaviour is observed. We also
study the effect of transmission on the evolution of different source terms of
the Friedmann equation. We conclude that among all semi-transparent branes the
slowest recollapse occurs for light branes with total absorption.

\\ ( http://arXiv.org/abs/hep-th/0603223 , 292kb)