Non-conventional cosmology from a brane universe

Abstract

We consider "brane-universes", where matter is confined to four-dimensional hypersurfaces (three-branes) whereas one extra compact dimension is felt by gravity only. We show that the cosmology of such branes is definitely different from standard cosmology and identify the reasons behind this difference. We give a new class of exact solutions with a constant five-dimensional radius and cosmologically evolving brane. We discuss various consequences.

Bouncing braneworlds go crunch!

“…Of course, the FRW constraint in this braneworld context also comes with an unconventional term quadratic in ρ [4].…”

“…In this region, we have r * → ±∞ as r → r ∓ . Finally, it will be useful to work with null coordinates, 4) with which the line element becomes ds 2 = V (r)du dv + r 2 dΣ 2 k . The massive Klein-Gordon equation in the charged black hole background (2.2) may be expanded as…”

“…Such scenarios provide a new framework in which to address many longstanding puzzles in particle physics, such as the hierarchy problem. The cosmology community has also shown an increasing interest in braneworlds [4,5], since this is another field where brane models have the potential to provide novel solutions to many of the perennial questions.…”

Brane cosmology solutions with bulk scalar fields

“…In general, effects arising from the extra dimensions in this setup will be incompatible with the observed behaviour of our universe. However, if a negative cosmological constant is added to the bulk, it is possible (to leading order) to reobtain standard four-dimensional gravity [1] and cosmology on the brane [2].…”

Cosmological consequences of the brane/bulk interaction

“…It was found that the Friedmann equation on the brane contains corrections to the usual four-dimensional equation. In particular a term H ∝ ρ was found [3]. This term is observationally problematic (e.g.…”