Determining the Neutrino Mass Ordering and Oscillation Parameters with KM3NeT/ORCA

Abstract

The next generation of water Cherenkov neutrino telescopes in the Mediterranean Sea are under construction offshore France (KM3NeT/ORCA) and Sicily (KM3NeT/ARCA). The KM3NeT/ORCA detector features an energy detection threshold which allows to collect atmospheric neutrinos to study flavour oscillation. This paper reports the KM3NeT/ORCA sensitivity to this phenomenon. The event reconstruction, selection and classification are described. The sensitivity to determine the neutrino mass ordering was evaluated and found to be 4.4 $\ddot{I}ƒ$ if the true ordering is normal and 2.3 $\ddot{I}ƒ$ if inverted, after three years of data taking. The precision to measure $\hat{I}”m_{32}^2$ and $\hat{I}{¸}_{23}$ were also estimated and found to be $85\cdot 10^{-6}$ eV${}^2$ and ${(}_{-3.1}^{+1.9}{)}^{\circ }$ for normal neutrino mass ordering and, $75\cdot 10^{-6}$ eV${}^2$ and ${(}_{-7.0}^{+2.0}{)}^{\circ }$ for inverted ordering. Finally, a unitarity test of the leptonic mixing matrix by measuring the rate of tau neutrinos is described. Three years of data taking were found to be sufficient to exclude $\hat{I}{½}_{\ddot{I}}„$ and $\bar{\hat{I}}{½}_{\ddot{I}}„$ event rate variations larger than 20% at $3\ddot{I}ƒ$ level.

Accepted for publication at EPJ-C