Various aspects of the neutrino mass problem are discussed in the light of existing model predictions and extensive experimental data. Generation mechanisms are considered and possible gauge-theory neutrino mass hierarchies, in particular the most popular ’flipped see-saw’ models, are discussed. Based on the currently available astrophysical data on the integral density of matter in the Universe and on the spectral anisotropy of the relic cosmic radiation, the cosmological implications of a non-zero neutrino mass are described in detail. Results from various mass-measuring methods are presented. Considerable attention is given to heavy neutrino oscillations. Oscillation mechanisms both in vacuum and in matter are considered in detail. Experiments on oscillations at low and high energies and new generation large-flight-base facilities are described. The present state of research into oscillations of solar and atmospheric neutrinos is reviewed.

PACS: 14.60.Pq, 12.15.Ff (all) DOI: 10.1070/PU1997v040n08ABEH000272 URL: https://ufn.ru/en/articles/1997/8/b/ A1997XX57300002 Citation: Gershtein S S, Kuznetsov E P, Ryabov V A "The nature of neutrino mass and the phenomenon of neutrino oscillations" Phys. Usp. 40 773–806 (1997) BibTexBibNote ® (generic)BibNote ® (RIS)MedlineRefWorks Оригинал: Герштейн С С, Кузнецов Е П, Рябов В А «Природа массы нейтрино и нейтринные осцилляции» УФН 167 811–848 (1997); DOI: 10.3367/UFNr.0167.199708b.0811