Sterile neutrinos with secret interactions—lasting friendship with cosmology
- International Center for Theoretical Physics, Strada Costiera 11, Trieste, 34014 Italy (Italy)
- Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai, 400005 India (India)
- PRISMA Cluster of Excellence and Mainz Institute for Theoretical Physics, Johannes Gutenberg University, Staudingerweg 7, Mainz, 55128 Germany (Germany)
Sterile neutrinos with mass ≅ 1 eV and order 10% mixing with active neutrinos have been proposed as a solution to anomalies in neutrino oscillation data, but are tightly constrained by cosmological limits. It was recently shown that these constraints are avoided if sterile neutrinos couple to a new MeV-scale gauge boson A'. However, even this scenario is restricted by structure formation constraints when A'-mediated collisional processes lead to efficient active-to-sterile neutrino conversion after neutrinos have decoupled. In view of this, we reevaluate in this paper the viability of sterile neutrinos with such ''secret'' interactions. We carefully dissect their evolution in the early Universe, including the various production channels and the expected modifications to large scale structure formation. We argue that there are two regions in parameter space—one at very small A' coupling, one at relatively large A' coupling—where all constraints from big bang nucleosynthesis (BBN), cosmic microwave background (CMB), and large scale structure (LSS) data are satisfied. Interestingly, the large A' coupling region is precisely the region that was previously shown to have potentially important consequences for the small scale structure of dark matter halos if the A' boson couples also to the dark matter in the Universe.
- OSTI ID:
- 22525292
- Journal Information:
- Journal of Cosmology and Astroparticle Physics, Vol. 2015, Issue 10; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1475-7516
- Country of Publication:
- United States
- Language:
- English
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