String loop origin for dark radiation and superheavy dark matter in type IIB compactifications

TL;DR

This paper explores how string loop corrections influence dark radiation and superheavy dark matter in type IIB compactifications, analyzing decay rates, reheating scenarios, and dark matter production mechanisms.

Contribution

It provides a detailed analysis of string loop effects on moduli stabilization, dark radiation origin, and dark matter production in type IIB string theory.

Findings

Decay rates of moduli to axions are significantly affected by higher-order corrections.

Reheating scenarios depend on decay rates, with $\Delta N_{eff}$ remaining within bounds.

A non-thermal dark matter scenario with masses from GeV to $10^{12}$ GeV is proposed.

Abstract

In this article we study the significance of string loop corrections, in a perturbative moduli stabilization scenario, focusing on their role in unraveling the origin of dark radiation in the late cosmological epoch and their correlation to dark matter. More specifically, a detailed analysis is provided in which the mass hierarchy of the normalized fields in the K{\"a}hler moduli sector is determined by the scales of the integer fluxes and the quantum corrections. Furthermore, we compute the previously underestimated contributions to the decay rates of moduli to axions, which behave as dark radiation, highlighting their connection to the aforementioned higher-order corrections. Two contrasting reheating scenarios (low-scale and high-scale) are provided, depending on the decay rate of the longest-lived particle into the Standard Model degrees of freedom through a Giudice-Masiero mechanism, while the effective number of neutrino species $\Delta N_{eff}$ remains below the respective bounds. Finally, a non-thermal dark matter scenario is proposed based on the decays of heavy scalar fields, where the main production mechanisms are investigated, leading to a dark matter candidate mass ranging from a few $GeV$ up to $10^{12}\; GeV$.