Cosmological Constraints on Strongly Coupled Moduli from Cosmic Strings

TL;DR

This paper investigates how strongly coupled moduli, produced by cosmic string loops, affect cosmological phenomena and derives constraints on their properties, showing that large coupling constants can relax these constraints.

Contribution

It provides new cosmological constraints on strongly coupled moduli from cosmic string effects, including thermal production, in specific string compactification models.

Findings

Constraints on cosmic string tension, modulus mass, and coupling constant are derived.

Large coupling constants significantly relax the constraints.

Thermal production effects are also analyzed and constrained.

Abstract

Cosmological constraints on moduli, whose coupling to matter is stronger than Planck mass suppressed coupling, are derived. In particular, moduli are considered to be produced by oscillating loops of cosmic strings and constraints are obtained from their effects on big bang nucleosynthesis and their contribution to diffuse gamma ray background and dark matter. Large volume and warped Type-IIB flux compactifications are taken as examples where strongly coupled moduli are present. Finally, the constraints on cosmic string tension, modulus mass and modulus coupling constant are obtained and it is shown that the constraints are relaxed significantly when the coupling constant is large enough. In addition, the effects of thermal production of moduli are considered and the corresponding constraints are derived.