Determining Neutrino Mass Ordering with ICAL, JUNO and T2HK

TL;DR

This study demonstrates that combining data from T2HK, ICAL, and JUNO experiments significantly enhances the sensitivity to neutrino mass ordering, achieving over 7 sigma confidence even under less favorable conditions.

Contribution

It provides a comprehensive analysis of the combined potential of future neutrino experiments to determine mass ordering, considering various experimental and physical parameter variations.

Findings

Combined experiments reach 7.2 sigma sensitivity for mass ordering.

Synergy arises from different oscillation channels favoring different parameters.

Sensitivity is robust against variations in JUNO energy resolution and other parameters.

Abstract

In this paper we study the synergy among the future accelerator (T2HK), future atmospheric (ICAL) and future reactor (JUNO) neutrino experiments to determine the neutrino mass ordering. T2HK can measure the mass ordering only for favorable values of $\delta_{\rm CP}$, whereas the mass ordering sensitivity of JUNO is dependent on the energy resolution. Our results show that with a combination of T2HK, ICAL and JUNO one can have a mass ordering sensitivity of 7.2 $\sigma$ even for the unfavorable value of $\delta_{\rm CP} = 0^\circ$ for T2HK and most conservative value of JUNO energy resolution of 5$\%/\sqrt{E(MeV)}$. The synergy mainly comes because different oscillation channels prefer different values of $|\Delta m_{31}^2|$ in the fit when the mass-ordering $\chi^2$ is minimized. In this context we also study: (i) effect of varying energy resolution of JUNO, (ii) the effect of longer run-time of ICAL, (iii) effect of different true values of $\theta_{23}$ and (iv) effect of octant degeneracy in the determination of neutrino mass ordering.