Speaker
Description
We propose a new approach to measuring the CP-violating phase in neutrino mixing using atmospheric neutrinos. We develop an up-down flux ratio for sub-GeV atmospheric neutrinos that incorporates realistic detection effects and reduces systematic uncertainties. For the example of Hyper-Kamiokande --- the first experiment with sufficient atmospheric-neutrino statistics in this energy range --- our approach can surpass the sensitivity of accelerator long-baseline experiments near the maximally CP-violating values δ=π/2 and 3π/2, which are favoured by current data. We discuss the work required to reduce theoretical uncertainties and fully realize the potential of this measurement. Combining accelerator and atmospheric analyses would enable the greatest sensitivity to the neutrino CP phase to be achieved in the shortest time.