Determination of the neutrino mass ordering by combining PINGU and Daya Bay II

TL;DR

This paper proposes a combined analysis of PINGU and Daya Bay II experiments to determine the neutrino mass ordering with high significance by exploiting the mismatch in |Delta m^2_31| measurements when assuming the wrong ordering.

Contribution

It introduces a novel synergy approach that leverages the different sensitivities of PINGU and Daya Bay II to improve neutrino mass ordering determination.

Findings

Synergy between PINGU and Daya Bay II enhances sensitivity.

Mismatch in |Delta m^2_31| measurements indicates wrong mass ordering.

Combined analysis can achieve high significance even with individual poor sensitivities.

Abstract

The relatively large measured value of theta_13 has opened various possiblities to determine the neutrino mass ordering, among them using PINGU, the low-energy extention of the IceCube neutrino telescope, to observe matter effects in atmospheric neutrinos, or a high statistics measurment of the neutrino energy spectrum at a reactor neutrino experiment with a baseline of around 60 km, such as the Daya Bay II project. In this work we point out a synergy between these two approaches based on the fact that when data are analysed with the wrong neutrino mass ordering the best fit occurs at different values of |Delta m^2_31| for PINGU and Daya Bay II. Hence, the wrong mass ordering can be excluded by a mismatch of the values inferred for |Delta m^2_31|, thanks to the excellent accuracy for Delta m^2_31 of both experiments. We perform numerical studies of PINGU and Daya Bay II sensitivities and show that the synergy effect may lead to a high significance determination of the mass ordering even in situations where the individual experiments obtain only poor sensitivity.