[SEMINARI]: Dr. Pastor: Unstable MeV neutrinos and primordial nucleosynthesis

[Arcadi Santamaria]

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                              S E M I N A R I

            [Image]    Departament de Física Teòrica     [Image]
                          Universitat de València
                      46100 Burjassot (València) Spain

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              Unstable MeV neutrinos and primordial nucleosynthesis

                                Sergio Pastor

                       (SISSA - INFN, Trieste (Italy))

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                     Aula de Seminaris de Física Teòrica
                  Tuesday 09 of March of 1999 at 04:30 PM
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                                    Resum

The impact of unstable MeV tau neutrinos on primordial nucleosynthesis (BBN)
   is considered for masses and lifetimes in the intervals 0.1-20 MeV and
     0.001-400 sec, respectively. The studied decay modes are nu_tau ->
 nu_mu(nu_e) + phi, where phi is a massless (or light) scalar. The Boltzmann
      kinetic equations are solved numerically without any simplifying
   assumptions. Depending on mass, lifetime, and decay channels of the tau
   neutrinos, the number of effective neutrino species at BBN (found from
     He-4), in addition to the 3 standard ones, varies from -2 to +2.5.

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