EVADING THE DIRAC-NEUTRINO-MASS CONSTRAINT FROM SN-1987A

If the right-handed singlet components (VR) Of Dirac neutrinos participate in an interaction with quarks via the exchange of scalar leptoquarks, supernova 1987A constraints on their masses can be evaded without running into gross conflict with nucleosynthesis results on the number of allowed neutrino species. Owing to an approximate SU(3)-flavor symmetry of the effective VR-quark four-fermion interaction, the v(R)'s freeze out sufficiently early from the hadronic matter (pi+/-, K+/-, nucleons, etc.) during the evoution of the Universe, contributing effectively as 0.5 of a neutrino species to nucleosynthesis, and yet are trapped inside the supernova core via their interaction with the nucleons.