Combined sensitivity of JUNO and KM3NeT/ORCA to the neutrino mass ordering

TL;DR

This paper explores how combining data from JUNO and KM3NeT/ORCA enhances the ability to determine the neutrino mass ordering, achieving high confidence within a few years.

Contribution

It demonstrates that a joint analysis of JUNO and KM3NeT/ORCA significantly improves neutrino mass ordering sensitivity beyond individual capabilities.

Findings

5σ determination after 6 years of data

2 years sufficient with current best-fit parameters

Combination removes degeneracy in Δm₃₁² measurement

Abstract

This article presents the potential of a combined analysis of the JUNO and KM3NeT/ORCA experiments to determine the neutrino mass ordering. This combination is particularly interesting as it significantly boosts the potential of either detector, beyond simply adding their neutrino mass ordering sensitivities, by removing a degeneracy in the determination of $\Delta m_{31}^2$ between the two experiments when assuming the wrong ordering. The study is based on the latest projected performances for JUNO, and on simulation tools using a full Monte Carlo approach to the KM3NeT/ORCA response with a careful assessment of its energy systematics. From this analysis, a $5\sigma$ determination of the neutrino mass ordering is expected after 6 years of joint data taking for any value of the oscillation parameters. This sensitivity would be achieved after only 2 years of joint data taking assuming the current global best-fit values for those parameters for normal ordering.