Phenomenological advantages of the normal neutrino mass ordering * * SFG is supported by JSPS KAKENHI (JP18K13536) and the Double First Class start-up fund (WF220442604) provided by Shanghai Jiao Tong University. JYZ is supported by the National Natural Science Foundation of China (11275101, 11835005)

Shao-Feng Ge,Jing-Yu Zhu

doi:10.1088/1674-1137/44/8/083103

Abstract

The preference of the normal neutrino mass ordering from the recent cosmological constraint and the global fit of neutrino oscillation experiments does not seem like a wise choice at first glance since it obscures the neutrinoless double beta decay and hence the Majorana nature of neutrinos. Contrary to this naive expectation, we point out that the actual situation is the opposite. The normal neutrino mass ordering opens the possibility of excluding the higher solar octant and simultaneously measuring the two Majorana CP phases in future experiments. Especially, the funnel region will completely disappear if the solar mixing angle takes the higher octant. The combined precision measurement by the JUNO and Daya Bay experiments can significantly reduce the uncertainty in excluding the higher octant. With a typical sensitivity on the effective mass , the neutrinoless double beta decay experiment can tell if the funnel region really exists and hence exclude the higher solar octant. With the sensitivity further improved to sub-meV, the two Majorana CP phases can be simultaneously determined. Thus, the normal neutrino mass ordering clearly shows phenomenological advantages over the inverted one.

Highlights

The neutrino oscillation [1, 2] is the first established new physics beyond the Standard Model (SM) of particle physics [3], it is not clear whether it is due to a genuine mass or just an environmental matter effect [4,5,6,7,8,9]
If there is an intelligent design behind the established oscillation patterns, it is hard to imagine that the 0ν2β decay for measuring the Majorana nature is left unattended
We try to explore the phenomenological potentials of the 0ν2β decay experiments with the normal ordering (NO), rather than making prediction on which mass ordering should be correct

Summary

Introduction

The neutrino oscillation [1, 2] is the first established new physics beyond the Standard Model (SM) of particle physics [3], it is not clear whether it is due to a genuine mass or just an environmental matter effect [4,5,6,7,8,9]. Even if the effective mass |mee| is not inside the funnel region, it is still much more difficult to measure the 0ν2β decay with NO.

Results

Conclusion