Gravitational production of a conformal dark sector

Dark sectors with purely gravitational couplings to the Standard Model are unavoidably populated from the SM plasma by graviton exchange, and naturally provide dark matter candidates. We examine the production in the relativistic regime where the dark sector is approximately scale invariant, providing general analytical formulas that depend solely on the central charge of the dark sector. We then assess the relevance of interactions that can lead to a variety of phenomena including thermalisation, non-perturbative mass gaps, out-of-equilibrium phase transitions and cannibalism in the dark sector. As an illustrative example we consider the dark glueball scenario in this light and show it to be a viable dark matter candidate due to the suppression of gravitational production. We go on to extend these results to strongly coupled CFTs and their holographic duals at large-N with the dark dilaton as the dark matter candidate.

Automated summary

This article examines dark sectors with gravitational couplings to the Standard Model, focusing on production in the relativistic regime and the impact of interactions leading to various phenomena. An illustrative example of the dark glueball scenario as a viable dark matter candidate is provided, with an extension to strongly coupled CFTs and their holographic duals with the dark dilaton as the dark matter candidate.