Neutrino Mass Ordering with Atmospheric, Long Baseline and Reactor Experiments

In this work, 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 \(\delta _{CP}\) , 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 unfavourable value of \(\delta _{CP}\) = \(0^{\circ }\) for T2HK and most conservative value of JUNO energy resolution of 5 \(\%/\sqrt{E(M eV )}\) . The synergy mainly comes because different oscillation channels prefer different values of \(|\Delta m^{2}_{31}|\) in the fit when the mass-ordering \(\chi ^{2}\) is minimized. In this context, we also study: (i) the effect of varying energy resolution of JUNO, (ii) the effect of longer run-time of ICAL, (iii) the effect of different true values of \(\theta _{23}\) and (iv) the effect of octant degeneracy in the determination of neutrino mass ordering.