Neutrino Mass Ordering through Inelasticity-Resolved Oscillation Spectroscopy

Giner Olavarrieta et al. (2024) show that including inelasticity in oscillation analyses (not just energy and angle) can boost sensitivity to mass ordering in IceCube-Upgrade/KM3NeT-ORCA. This idea can be extended by developing new, high-resolution inelasticity reconstruction algorithms—possibly using deep learning or new detector technologies—to enable “oscillation spectroscopy” where both the neutrino energy and inelasticity are jointly fit. This multidimensional approach can break degeneracies in oscillation parameter extraction, improve robustness against cross-section uncertainties (see Coyle et al. 2025), and even provide a new handle on non-standard interactions (which often alter inelasticity distributions). By pushing the method to its limits, including at lower energies and in other experiment types (e.g., reactor, accelerator), this could deliver definitive mass ordering determination and uncover subtle signatures of BSM physics.

References:

1. Boosting neutrino mass ordering sensitivity with inelasticity for atmospheric neutrino oscillation measurement. Santiago Giner Olavarrieta, Miaochen Jin, C. Argüelles, P. Fernández, Ivan Mart'inez-Soler (2024). Physical Review D.
2. Neutrino-nucleus cross section impacts on neutrino oscillation measurements. Nina M. Coyle, Shirley Weishi Li, P. Machado (2025). Physical Review D.