Neutrino telescopes as a probe of active and sterile neutrino mixings

Abstract

If the ultrahigh-energy (UHE) neutrino fluxes produced from a distant astrophysical source can be measured at a km3-size neutrino telescope, they will provide a promising way to help determine the flavor mixing pattern of three active neutrinos. Considering the conventional UHE neutrino source with the flavor ratio ϕ e : ϕ μ : ϕ τ = 1 : 2 : 0 , I show that ϕ e D : ϕ μ D : ϕ τ D = ( 1 − 2 Δ ) : ( 1 + Δ ) : ( 1 + Δ ) holds at the detector of a neutrino telescope, where Δ characterizes the effect of μ-τ symmetry breaking (i.e., θ 13 ≠ 0 and θ 23 ≠ π / 4 ). Current experimental data yield − 0.1 ⩽ Δ ⩽ + 0.1 . It is also possible to probe Δ by detecting the ν ¯ e flux of E ν ¯ e ≈ 6.3 PeV via the Glashow resonance channel ν ¯ e e → W − → anything. Finally, I give some brief comments on the possibility to constrain the mixing between active and sterile neutrinos by using the UHE neutrino telescopes.