Problem of the atmospheric neutrinos

The cosmic rays interact in the high layers of the atmosphere and produce pawns and kaons which disintegrate in muons and muon neutrinos. The muons disintegrate in their turn in $\ nu_e$ , $\ nu_ {\ driven}$ and $e^-$ . The produced particles are very energy. Theoretically one must observe approximately twice more $\ nu_ {\ driven}$ that of $\ nu_e$ . The many experiments (in particular SuperKamiokande) showed a clear reduction in the number of $\ nu_ {\ driven}$ detected according to the zenith angle. Muon neutrinos coming atmosphere with the antipodes, after having crossed the Earth, are definitely fewer. The variation of the deficit of $\ nu_ {\ driven}$ according to the zenith angle can be explained only by oscillations. The oscillations $\ nu_ {\ driven} \ leftrightarrow \ nu_ {\ tau}$ could make it possible to explain the phenomenon. Indeed, the oscillations of the $\ nu_e$ would be very low and the diameter of the Earth in fact of the same order of magnitude as the length of oscillation for the oscillations $\ nu_ {\ driven} \ leftrightarrow \ nu_ {\ tau}$ . Currently the best values are $\ theta \ simeq 45$ ° and $\ Delta m^2 \ simeq 2.5 \ times 10^ {- 3} eV^2$ . It is about the same value of the angle of mixture as for the oscillations of the neutral kaons.

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