Divergence in tracing the flavors of astrophysical neutrinos: can JUNO help IceCube?
Authors
Zhi-zhong Xing
Abstract
We derive the flavor fractions $(η^{}_e , η^{}_μ, η^{}_τ)$ for ultrahigh-energy neutrinos originating from a remote astrophysical source by using their flavor ratios $(f^{}_e , f^{}_μ, f^{}_τ)$ observed at a neutrino telescope, and find that a potential divergence may appear in inferring the values of $η^{}_μ$ and $η^{}_τ$ as an unavoidable consequence of the approximate $μ$-$τ$ interchange symmetry of lepton flavor mixing. We illustrate such an effect by applying our formula to the IceCube all-sky neutrino flux data ranging from 5 TeV to 10 PeV in the naive assumption that the relevant sources have a common flavor composition. We show that only $η^{}_e$ and $η^{}_μ+ η^{}_τ$ can be extracted from the measurements of $f^{}_e$, $f^{}_μ$ and $f^{}_τ$ if the $μ$-$τ$ flavor symmetry is exact, and the JUNO and Daya Bay precision antineutrino oscillation data will help a lot in this connection.
