Heating in Brane Inflation and Hidden Dark Matter

TL;DR

This paper explores how energy transfer during brane inflation can produce viable hot big bang conditions, suppress unwanted relics, and introduces new hidden dark matter candidates arising from warped geometry and KK modes.

Contribution

It presents a detailed analysis of energy transfer mechanisms in brane inflation scenarios, introduces a dynamical selection of the SM throat, and proposes three new hidden dark matter candidates.

Findings

Energy transfer can be efficient enough for big bang nucleosynthesis.

Warped geometry suppresses graviton and KK relics.

Three new hidden dark matter candidates are identified.

Abstract

Towards the end of brane inflation, the brane pair annihilation produces massive closed strings. The transfer of this energy to Standard Model (SM) open string modes depends on where the SM branes and the brane annihilation are located: in the bulk, in the same throat or in different throats. We find that, in all cases as long as the brane annihilation and the SM branes are not both in the bulk, the transfer of energy to start the hot big bang epoch can be efficient enough to be compatible with big bang nucleosynthesis. The suppression of the abundance of the graviton and its Kaluza-Klein (KK) thermal relics follows from the warped geometry in flux compactification. This works out even in the scenarios where a long period of tunneling is expected. In the multi-throat scenario, we find a dynamical mechnism of selecting a long throat as the SM throat. We establish three new dark matter candidates: KK modes with specific angular momentum in the SM throat, those in the brane annihilation throat, and different matters generated by KK modes tunneled to other throats. Since the latter two couple to the visible matter sector only through graviton mediation, they behave as hidden dark matter. Hidden dark matter has novel implications on the dark matter coincidence problem and the high energy cosmic rays.