Throat Cosmology

TL;DR

This thesis investigates energy transfer in string theory throats during the early universe, calculating decay rates and exploring their potential as dark matter candidates based on cosmological and particle physics implications.

Contribution

It provides new calculations of heat transfer and decay rates of throat-localized states using gauge theory duals, including effects of flux compactifications and tachyonic scalars.

Findings

Throats with certain infrared scales can account for dark matter if reheating temperature is high.

Decay rates of Kaluza-Klein modes are highly suppressed, leading to potential dark matter stability.

Possible gamma-ray signals from throat decays could be detectable.

Abstract

In this thesis, we study throats in the early, hot universe. Throats are a common feature of the landscape of type IIB string theory. If a throat is heated during cosmological evolution, energy is subsequently transferred to other throats and to the standard model. We calculate the heat transfer rate and the decay rate of throat-localized Kaluza-Klein states in a ten-dimensional model. For the calculation, we employ the dual description of the throats in terms of gauge theories. We discuss modifications of the decay rate which arise in flux compactifications and for Klebanov-Strassler throats and emphasize the role of tachyonic scalars in such throats in mediating decays of Kaluza-Klein modes. Our results are also applicable to the energy transfer from the heated standard model to throats. We determine the resulting energy density in throats at our epoch in dependence of their infrared scales and of the reheating temperature. The Kaluza-Klein modes in the throats decay to other sectors with a highly suppressed rate. If their lifetime is longer than the age of the universe, they are an interesting dark matter candidate. We show that, if the reheating temperature was 10^10 - 10^11 GeV, throats with infrared scales in the range of 10^5 GeV to 10^10 GeV can account for the observed dark matter. We identify several scenarios where this type of dark matter is sufficiently stable but where decays to the standard model can be discovered via gamma-ray observations.