6533b7d2fe1ef96bd125e2ac
RESEARCH PRODUCT
Relic Neutrino Decoupling Including Flavour Oscillations
T. PintoSergio PastorOfelia PisantiPasquale D. SerpicoGianpiero ManganoGennaro Mielesubject
PhysicsNuclear and High Energy PhysicsParticle physicsPhotonPhysics::Instrumentation and DetectorsAstrophysics::High Energy Astrophysical PhenomenaFlavourAstrophysics (astro-ph)High Energy Physics::PhenomenologyFOS: Physical sciencesFísicaNeutrino decouplingSolar neutrino problemAstrophysicsHigh Energy Physics - PhenomenologyHigh Energy Physics - Phenomenology (hep-ph)Measurements of neutrino speedHigh Energy Physics::ExperimentNeutrinoNeutrino oscillationLeptondescription
In the early universe, neutrinos are slightly coupled when electron-positron pairs annihilate transferring their entropy to photons. This process originates non-thermal distortions on the neutrino spectra which depend on neutrino flavour, larger for nu_e than for nu_mu or nu_tau. We study the effect of three-neutrino flavour oscillations on the process of neutrino decoupling by solving the momentum-dependent kinetic equations for the neutrino spectra. We find that oscillations do not essentially modify the total change in the neutrino energy density, giving N_eff=3.046 in terms of the effective number of neutrinos, while the small effect over the production of primordial 4He is increased by O(20%), up to 2.1 x 10^{-4}. These results are stable within the presently favoured region of neutrino mixing parameters.
| year | journal | country | edition | language |
|---|---|---|---|---|
| 2005-06-16 |