Dark matter production via a non-minimal coupling to gravity

Abstract

We study postinflationary scalar dark matter production via its non-minimal coupling to gravity. During the inflaton oscillation epoch, dark matter is produced resonantly for a sufficiently large non-minimal coupling $\xi \gtrsim 5$. We find that backreaction on the curvature and rescattering effects typically become important for the values of $\xi$ above $30$, which invalidate simple estimates of the production efficiency. At large couplings, the dark matter yield becomes almost independent of $\xi$, signifying approximate quasi-equilibrium in the inflaton-dark matter system. Although the analysis gets complicated by the presence of apparent negative energy in the Jordan frame, this behaviour can be regularized by introducing mild dark matter self-interaction. Using lattice simulations, we delineate parameter space leading to the correct dark matter relic abundance.

18 pages, 7 figures; v2: matches version published in JCAP (added minor clarifications, fixed typos, added references)

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• Gravitational Wave Probe of Gravitational Dark Matter from Preheating
• Physical scale adiabatic regularization in cosmological spacetimes
• The Second-Level Preheating
• Einstein-Yang-Mills Regular Black Holes in Rainbow Gravity
• Fermion (non)reheating with a quartic inflaton potential