N. Okada et O. Yasuda, A STERILE NEUTRINO SCENARIO CONSTRAINED BY EXPERIMENTS AND COSMOLOGY, International journal of modern physics A, 12(21), 1997, pp. 3669-3694
We analyze a scheme in which three active neutrinos and one sterile ne
utrino account for the solar, the atmospheric and the LSND neutrino an
omalies in a model-independent way. It is shown that if the equivalent
number, N-nu, of the light neutrino species is less than 4, then the
constraints from these anomalies, accelerator and reactor experiments
and big bang nucleosynthesis force a general 4 x 4 mixing matrix to be
effectively split into two 2 x 2 matrices. If these neutrinos are of
the Majorana type, then negative results of neutrinoless double beta d
ecay experiments imply that the total mass of neutrinos is not suffici
ent to account for all the hot dark matter components.