The strongest bounds on active-sterile neutrino mixing after Planck data

Alessandro Mirizzi, Gianpiero Mangano, Ninetta Saviano, Enrico Borriello, Carlo Giunti, Gennaro Miele, Ofelia Pisanti

Research output: Contribution to journalArticlepeer-review

67 Scopus citations


Light sterile neutrinos can be excited by oscillations with active neutrinos in the early universe. Their properties can be constrained by their contribution as extra-radiation, parameterized in terms of the effective number of neutrino species Neff, and to the universe energy density today Ωνh2. Both these parameters have been measured to quite a good precision by the Planck satellite experiment. We use this result to update the bounds on the parameter space of (3+1) sterile neutrino scenarios, with an active-sterile neutrino mass squared splitting in the range (10-5-102)eV2. We consider both normal and inverted mass orderings for the active and sterile states. For the first time we take into account the possibility of two non-vanishing active-sterile mixing angles. We find that the bounds are more stringent than those obtained in laboratory experiments. This leads to a strong tension with the short-baseline hints of light sterile neutrinos. In order to relieve this disagreement, modifications of the standard cosmological scenario, e.g. large primordial neutrino asymmetries, are required.

Original languageEnglish (US)
Pages (from-to)8-14
Number of pages7
JournalPhysics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics
Issue number1-3
StatePublished - 2013
Externally publishedYes

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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