Can atmospheric neutrino experiments provide the first hint of leptonic CP violation?

TL;DR

Atmospheric neutrino experiments, especially with the ICAL detector at INO, can significantly enhance the potential to detect leptonic CP violation when combined with T2K and NOvA, possibly providing the first hint.

Contribution

This study demonstrates for the first time that atmospheric neutrino data can improve the sensitivity to leptonic CP violation when combined with existing long-baseline experiments.

Findings

Adding atmospheric neutrino data doubles the CP violation sensitivity range.

Atmospheric neutrino data can provide the first hint of CP violation in certain parameter regions.

Combination of experiments enhances overall detection prospects.

Abstract

The measurement of a non-zero value of the 1-3 mixing angle has paved the way for the determination of leptonic CP violation. However the current generation long-baseline experiments T2K and NOvA have limited sensitivity to delta_{CP}. In this paper we show for the first time, the significance of that atmospheric neutrino experiments in providing the first hint of CP violation in conjunction with T2K and NOvA. In particular, we find that adding atmospheric neutrino data from the ICAL detector at the India-based Neutrino Observatory (INO) to T2K and NOvA results in a two-fold increase in the range of delta_{CP} values for which a 2 sigma hint of CP violation can be obtained. In fact in the parameter region unfavorable for the latter experiments, the first signature of CP violation may well come from the inclusion of atmospheric neutrino data.