WIMPs during Reheating

Nicolás Bernal and Yong Xu

Submitted on 15 September 2022


Weakly Interacting Massive Particles (WIMPs) are among the best-motivated dark matter candidates. In the standard scenario where the freeze-out happens well after the end of inflationary reheating, they are in tension with the severe experimental constraints. Here, we investigate the thermal freeze-out of WIMPs occurring {\it during} reheating, while the inflaton ϕ coherently oscillates in a generic potential ϕn. Depending on the value of n and the spin of the inflaton decaying products, the evolution of the radiation and inflaton energy densities can show distinct features, therefore, having a considerable impact on the freeze-out behavior of WIMPs. As a result of the injection of entropy during reheating, the parameter space compatible with the observed DM relic abundance is enlarged. In particular, the WIMP thermally averaged annihilation cross-section can be several magnitudes lower than that in the standard case. Finally, we discuss the current bounds from dark matter indirect detection experiments, and explore future challenges and opportunities.


Comment: 19 pages, 5 figures

Subjects: High Energy Physics - Phenomenology; Astrophysics - Cosmology and Nongalactic Astrophysics