All existing data on neutrino oscillations (including those from the LSND experiment) imply a four neutrino scheme with six different allowed mass patterns. Some of the latter are shown to be disfavored by using a conservative upper bound on the $\beta beta 0 \nu$ nuclear decay rate, if neutrinos are assumed to be Majorana particles. Comparisons are also made with restrictions from tritium $\beta$-decay and cosmology.
Categories: hep-ph astro-ph hep-ex