Neutrino oscillations in the early universe with an inverted neutrino-mass hierarchy
1993; Elsevier BV; Volume: 318; Issue: 1 Linguagem: Inglês
10.1016/0370-2693(93)91795-o
ISSN1873-2445
AutoresV. Alan Kostelecký, Stuart Samuel,
Tópico(s)Particle physics theoretical and experimental studies
ResumoNuclear simulations of neutrino oscillations in the early Universe are performed for a neutrino-mass hierarchy with the vacuum mass of the second neutrino exceeding that of the first. This situation is equivalent to a normal hierarchy with mixing angle greater than π4. We find that a large conversion of electron neutrinos to muon neutrinos occurs, independent of mixing angle. For certain parameter values, this is caused by the MSW effect. In the rest of the parameter region a new mechanism is operative, arising from nonlinear effects involving neutrino-neutrino forward scattering. This nonlinear conversion mechanism causes substantial flavor oscillation even for extremely small mixing angles.
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