Boosting Neutrino Mass Ordering Sensitivity with Inelasticity for Atmospheric Neutrino Oscillation Measurements

Neutrino telescopes cannot distinguish between neutrinos and antineutrinos on an event-by-event basis. Rather, they can do so on a statistical basis, that is, by considering a large dataset of events and exploiting kinematic variables for which different event distributions emerge between neutrinos and antineutrinos. So far, however, analyses in water(ice)-Cherenkov neutrino telescopes aimed at determining neutrino oscillation parameters have not exploited such kinematic variables. This limits the potential of these telescopes to use atmospheric neutrinos for measuring the different oscillation effects between neutrinos and antineutrinos, which would help in improving their sensitivity to parameters such as the neutrino mass ordering, δ_CP, and △m²₃₁. In this talk, I will share preliminary results of research on the effects of including an event’s inelasticity in the IceCube-Upgrade and ORCA detectors. This inclusion is done by considering muon neutrino charged-current interactions and separately reconstructing the track and cascade energies, thereby inferring an event's inelasticity. We find that the combined mass ordering sensitivity of both experiments increased from ~7σ to ~8.4σ, and we can exclude values of δ_CP with greater than ~2σ significance (up from ~1σ without the inelasticity). Lastly, we find a ~30% improvement in the resolution of △m²₃₁, achieving a precision for its value below the percent level (~0.7%).