Thermal neutrino portal to sub-MeV dark matter

Journal Article · 23 May 2019 · Physical Review. D.

DOI: https://doi.org/10.1103/physrevd.99.095030 · OSTI ID:1515568

Berlin, Asher ^[1]; Blinov, Nikita ^[1]

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1. SLAC National Accelerator Lab., Menlo Park, CA (United States)

Thermal relics lighter than an MeV add to the energy density of the universe at the time of nucleosynthesis and recombination. Constraints on extra radiation degrees of freedom typically exclude even the simplest of such dark sectors. We explore the possibility that a sub-MeV dark sector entered equilibrium with the Standard Model after neutrino-photon decoupling, which significantly weakens these constraints and naturally arises in the context of neutrino mass generation through the spontaneous breaking of the lepton number. Acquiring an adequate dark matter abundance independently motivates the MeV scale in these models through the coincidence of gravitational, matter-radiation equality, and neutrino mass scales, (m_Pl /T^MRE)^1/4m_ν ~ MeV . This class of scenarios will be decisively tested by future measurements of the cosmic microwave background and matter structure of the universe. While the dark sector dominantly interacts with Standard Model neutrinos, large couplings to nucleons are possible in principle, leading to observable signals at proposed low-threshold direct detection experiments.

• Research Organization: SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: AC02-76SF00515; NSF PHY-1748958
• OSTI ID: 1515568
• Alternate ID(s): OSTI ID: 1532390
• Journal Information: Physical Review. D., Vol. 99, Issue 9; ISSN 2470-0010
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English