A Non-thermal WIMP Miracle

TL;DR

This paper proposes that non-thermal WIMPs produced from decaying scalar fields in the early universe can naturally explain the observed dark matter density, offering a potential solution to the cosmological moduli problem.

Contribution

It introduces a novel non-thermal WIMP scenario that aligns with string theory predictions and addresses the cosmological moduli problem.

Findings

Non-thermal WIMPs can account for dark matter relic density.

Decays of scalar fields before BBN produce suitable WIMP abundances.

The scenario is potentially generic in string theory models.

Abstract

Light scalar fields with only gravitational strength couplings are typically present in UV complete theories of physics beyond the Standard Model. In the early universe it is natural for these fields to dominate the energy density, and their subsequent decay, if prior to BBN, will typically yield some dark matter particles in their decay products. In this paper we make the observation that a Non-thermal WIMP `Miracle' may result: that is, in the simplest solution to the cosmological moduli problem, non-thermally produced WIMPs can naturally account for the observed dark matter relic density. Such a solution may be generic in string theory compactifications.