Year: 2020
Type: article
Abstract: We present a new mechanism for thermally produced dark matter, based on a semi-annihilation-like process, $\ensuremath{\chi}+\ensuremath{\chi}+\mathrm{SM}\ensuremath{\rightarrow}\ensuremath{\chi}+\mathrm{SM}$, with intriguing consequences for the properties of dark matter. First, its mass is low, $\ensuremath{\lesssim}1\text{ }\text{ }\mathrm{GeV}$ (but $\ensuremath{\gtrsim}5\text{ }\text{ }\mathrm{keV}$ to avoid structure-formation constraints). Second, it is strongly interacting, leading to kinetic equilibrium between the dark and visible sectors, avoiding the structure-formation problems of $\ensuremath{\chi}+\ensuremath{\chi}+\ensuremath{\chi}\ensuremath{\rightarrow}\ensuremath{\chi}+\ensuremath{\chi}$ models. Third, in the $3\ensuremath{\rightarrow}2$ process, one dark matter particle is consumed, giving the standard-model particle a monoenergetic recoil. We show that this new scenario is presently allowed, which is surprising (perhaps a ``minor miracle''). However, it can be systematically tested by novel analyses in present and near-term experiments. In particular, the Co-SIMP model for thermal-relic dark matter can explain the XENON1T excess.
Source: Physical Review Letters
Authors: Juri Smirnov, John F. Beacom
Institution: The Ohio State University
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,750
OpenAlex ID: W3005778081