Atmospheric neutrinos and ν-mass hierarchy

Abstract

We discuss the possibility for matter effects in the three-neutrino oscillations of the atmospheric ν e ( ν ¯ e ) and ν μ ( ν ¯ μ ) , driven by one neutrino mass squared difference, | Δ m 31 2 | ≫ Δ m 21 2 , to be observable under appropriate conditions. We derive predictions for the Nadir angle (θn) dependence of the ratio Nμ/Ne of the rates of the μ–like and e–like multi-GeV events which is particularly sensitive to the Earth matter effects in the atmospheric neutrino oscillations, and thus to the values of sin 2 θ 13 and sin 2 θ 23 , and also to the type of neutrino mass spectrum.