6533b856fe1ef96bd12b2656

RESEARCH PRODUCT

Neff versus the lightest neutrino mass

Marija Kekic

subject

PhysicsNuclear and High Energy PhysicsParticle physicsSterile neutrino010308 nuclear & particles physicsSolar neutrinoHigh Energy Physics::PhenomenologyNeutrino decouplingSolar neutrino problem01 natural sciencesseesaw modelCosmic neutrino backgroundNuclear physicssterile neutrinos0103 physical sciencesMeasurements of neutrino speedHigh Energy Physics::ExperimentNeutrino010306 general physicsNeutrino oscillation

description

AbstractWithin the framework of low-scale Type I seesaw models with two and three extra sterile neutrinos we evaluate the production of the sterile states in the Early Universe. We explore the full parameter space and find that in the model with two extra states both of them reach thermal equilibrium with the primordial plasma. In the model with three sterile neutrinos, if the lightest active neutrino mass is below O(10−3eV) one sterile neutrino might not thermalize, while the other two always reach thermalization. Applying constrains from both extra radiation at BBN and CMB, and the dark matter allowed abundance, we show that the spectra of heavier states are severely restricted in the mass range 1eV–100MeV. The possible impact of extra sterile neutrinos on neutrinoless double beta decay is also discussed.

https://doi.org/10.1016/j.nuclphysbps.2015.09.287