Nonstandard interaction effects on neutrino parameters at medium-baseline reactor antineutrino experiments

Tommy Ohlsson,He Zhang,Shun Zhou

doi:10.1016/j.physletb.2013.11.052

Abstract

Precision measurements of leptonic mixing parameters and the determination of the neutrino mass hierarchy are the primary goals of the forthcoming medium-baseline reactor antineutrino experiments, such as JUNO and RENO-50. In this work, we investigate the impact of nonstandard neutrino interactions (NSIs) on the measurements of {sin2θ12,Δm212} and {sin2θ13,Δm312}, and on the sensitivity to the neutrino mass hierarchy, at the medium-baseline reactor experiments by assuming a typical experimental setup. It turns out that the true mixing parameter sin2θ12 can be excluded at a more than 3σ level if the NSI parameter εeμ or εeτ is as large as 2% in the most optimistic case. However, the discovery reach of NSI effects has been found to be small, and depends crucially on the CP-violating phases. Finally, we show that NSI effects could enhance or reduce the discrimination power of the JUNO and RENO-50 experiments between the normal and inverted neutrino mass hierarchies.

Highlights

The experimental endeavor in the past decades has established that the phenomenon of neutrino flavor transitions is described by neutrino oscillations at leading order
Recent studies indicate that a dedicated medium-baseline reactor antineutrino experiment with sufficient statistics and unprecedented detector performance provides an opportunity to determine the neutrino mass hierarchy and probe with high precision the other neutrino parameters
Beyond the standard oscillation picture, new physics may appear in future neutrino experiments in the form of unknown couplings involving neutrinos, which are usually referred to as nonstandard neutrino interactions [9,10,11,12,13] (NSIs)

Summary

INTRODUCTION

The experimental endeavor in the past decades has established that the phenomenon of neutrino flavor transitions is described by neutrino oscillations at leading order. That the smallest leptonic mixing angle θ13 has been measured very accurately at reactor [1,2,3,4] and accelerator [5] neutrino experiments, one of the major and open problems is the discrimination between normal and inverted neutrino mass hierarchies. Recent studies indicate that a dedicated medium-baseline reactor antineutrino experiment with sufficient statistics and unprecedented detector performance provides an opportunity to determine the neutrino mass hierarchy and probe with high precision the other neutrino parameters We investigate NSI effects at a typical medium-baseline reactor antineutrino experiment, in particular, the mimicking effects in the precision measurements of neutrino parameters, the discovery reach of NSI effects, and the distortion of the neutrino mass hierarchy determination.

BASIC FORMALISM

NUMERICAL ANALYSIS

Energy distribution

Discovery reach

Impact on the neutrino mass hierarchy determination

SUMMARY AND CONCLUSIONS