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

The measurement of a nonzero 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 NOνA have limited sensitivity to ΔCP. In this paper, we show, for the first time, the significance of atmospheric neutrino experiments in providing the first hint of CP violation in conjunction with T2K and NOνA. In particular, we find that adding atmospheric neutrino data from a magnetized iron calorimeter detector at the India-Based Neutrino Observatory to T2K and NOνA results in a twofold increase in the range of ΔCP values for which a 2σ 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