Cherenkov emissions of Langmuir plasmons and light neutrinosby the flux of neutrinos

We consider the system of neutrino-antineutrino (v[overline v]) - plasma taking into account theirweak Fermi interaction, when the density of neutrinos ν andthe plasma particles are rather high and their collective interactionplays a vital role. New fluid instabilities driven by strong neutrino flux in aplasma are observed. It is shown that a bunch of neutrinos, drifting witha constant velocity across a homogeneous plasma, can also induce emission oflower energy neutrinos due to scattering, i.e. the decay of a heavy neutrinoν^sub H^ into a heavy and a light neutrino ν^sub L^(ν^sub H^[arrow right]ν^sub H^ν^sub L^) in a plasma. Furthermore we find thatthe neutrino production in stars does not lead in general to energy lossesfrom the neutron stars.[PUBLICATION ABSTRACT]