Bouncing pre-big bang on the brane

Abstract

A regular bouncing universe is obtained in the context of a dilaton-gravity brane world scenario.The scale factor starts in a contracting inflationary phase both in the Einstein and in the string frame, it then undergoes a bounce (due to interaction with the bulk Weyl tensor), and subsequently enters into a decelerated expanding era. This graceful exit is obtained at low curvature and low coupling, and without violating the Null Energy Condition.

Bouncing cosmologies

“…(231)) κ is the bulk gravitational coupling, G N the effective Newton constant on the (d + 1)-dimensional brane, E is the projection of the bulk brane Weyl tensor on the brane, and T µ ν = (−R, P ) is the projection of the bulk energy-momentum tensor on the brane. It follows from this equation that a necessary condition to have a bounce without resorting to exotic forms of matter (that is, matter that violates ρ > 0 or ρ p > 0) is a negative E 0 0 [113]. This is precisely the approach taken in [276,114], where a brane evolving in a charged AdS black hole background was studied.…”

“…(231) we see that a necessary condition to have a bounce with ρ > 0 in the ǫ = 0, −1 cases is that either Λ < 0 or U < 0, or both. The case that includes matter in the bulk, without cosmological constant for a flat FLRW d + 1-dimensional was studied in [113]. A neceessary condition in order to have a bounce is that dH/dt > 0, with…”

Graceful entrance to braneworld inflation

“…Our observable four-dimensional universe is interpreted as a co-dimension one brane propagating in a five-(or higher-) dimensional 'bulk' space. A number of bouncing braneworld models have been developed to date [26,27,28,29,30,31]. In the model proposed by Shtanov and Sahni (S-S), for example, the extra bulk dimension is timelike and this results in modifications to the effective four-dimensional Friedmann equation that induce a non-singular bounce [26].…”

Analytic solutions to compact binary inspirals with leading order spin-orbit contribution using the dynamical renormalization group

“…During the inspiral, the binary slowly loses energy and angular momentum to gravitational radiation starting at 2.5PN [7,8]. Higher order corrections up to 4PN in the conservative sector have been calculated [9][10][11][12][13][14][15][16][17]. Solving for the motions is the fundamental step in obtaining the waveforms and deriving the evolution of the theoretical physical measurements in time, such as the GW phase directly measured by the detectors and power loss due to gravitational radiations.…”