2017/01/30 by Daniel Green, Surjeet Rajendran · 1 voice · 52 citations
Physics and Astronomy · #Atomic and Subatomic Physics Research #Cosmic microwave background #Cosmology #Dark Matter and Cosmic Phenomena #Dark matter #Hot dark matter #Neutrino #Neutrino Physics Research #Parameter space #Scalar field dark matter #Thermalisation #astro-ph.CO #hep-ph #hep-th
paper · pdf · doi:10.1007/jhep10(2017)013
published in Journal of High Energy Physics 2017(10) (Springer Nature) · 24 pages, 5 figures; V2: figures corrected, minor changes; V3: additional stellar cooling constraint included
arxiv published 2017/01/30 · openalex created_date 2017/02/10 · openalex publication_date 2017/10/01 · arxiv created 2018/02/28 · arxiv updated 2018/03/02 · openalex updated_date 2026/08/06
Light dark matter is a compelling experimental target in light of stringent constraints on heavier WIMPs. However, for a sub-MeV WIMP, the universe is sufficiently well understood at temperatures below 10 MeV that there is no room for it to be a thermal relic. Avoiding thermalization is itself a strong constraint with significant implications for direct detection. In this paper, we explore the space of models of sub-MeV dark matter with viable cosmologies. We discuss several representative models chosen to have large cross-sections in direct detection experiments. The parameter space of these models that is also consistent with astrophysical and lab-based limits is highly restricted for couplings to electrons but somewhat less constrained for nuclei. We find that achieving nuclear cross-sections well-above the neutrino floor necessarily predicts a new contribution to the effective number of neutrino species, ΔN eff = 0.09 that will be tested by the next generation of CMB observations. On the other hand, models with absorption signatures of dark matter are less restricted by cosmology even with future observations.