Paper detail

A further study of μ-τsymmetry breaking at neutrino telescopes after the Daya Bay and RENO measurements of θ_{13}

Current neutrino oscillation data indicate that θ_{13} is not strongly suppressed and θ_{23} might have an appreciable deviation from π/4, implying that the 3 \times 3 neutrino mixing matrix V does not have an exact μ-τpermutation symmetry. We make a further study of the effect of μ-τsymmetry breaking on the democratic flavor distribution of ultrahigh-energy (UHE) cosmic neutrinos at a neutrino telescope, and find that it is characterized by |V_{μi}|^2 - |V_{τi}|^2 which would vanish if either θ_{23} = π/4 and θ_{13} = 0 or θ_{23} = π/4 and δ= \pm π/2 held. We observe that the second-order μ-τsymmetry breaking term \barΔ may be numerically comparable with or even larger than the first-order term Δin the flux ratios ϕ^{T}_e : ϕ^{T}_μ: ϕ^{T}_τ\simeq (1- 2Δ) : (1 + Δ+ \barΔ) : (1 + Δ- \barΔ), if \sin (θ_{23} - π/4) and \cosδhave the same sign. The detection of the UHE \barν_e flux via the Glashow-resonance channel \barν_e e \to W^- \to anything is also discussed by taking account of the first- and second-order μ-τsymmetry breaking effects.