SOME REMARKS ON THE PROBLEM OF NEUTRINO OSCILLATION IN VACUUM AND MATTER

The paper deals with the analysis of possible neutrino oscillation typ es in vacuum and matter. The conclusion is that: 1) If masses of diffe rent types of neutrinos are equal, then a real oscillation of differen t types of neutrinos is possible by analogy with K0, KBAR0 oscillation . 2) If masses of different types of neutrinos are different, then onl y a virtual neutrino oscillation is possible, and a real oscillation o f neutrinos requires their participation in the interactions for trans ition to the appropriate to the rho0-meson in the vector dominance mod el. The enhanced oscillation probability is estimated for neutrinos of different masses in their passing through matter of different thickne ss, including the Sun. If it is assumed that the deficit of Sun neutri nos arises from neutrino oscillations, then using the GALLEX and SSM d ata we obtain that sin2 2theta congruent-to 0.015.