Neutrino versus antineutrino oscillation parameters at DUNE and Hyper-Kamiokande experiments

Testing, in a nontrivial, model-independent way, the hypothesis that the three-massive-neutrinos paradigm properly describes nature is among the main goals of the current and the next generation of neutrino oscillation experiments. In the coming decade, the DUNE and Hyper-Kamiokande experiments will be able to study the oscillation of both neutrinos and antineutrinos with unprecedented precision. We explore the ability of these experiments, and combinations of them, to determine whether the parameters that govern these oscillations are the same for neutrinos and antineutrinos, as prescribed by the CPT-theorem. We find that both DUNE and Hyper-Kamiokande will be sensitive to unexplored levels of leptonic CPT-violation. Assuming the parameters for neutrino and antineutrino oscillations are unrelated, we discuss the ability of these experiments to determine the neutrino and antineutrino mass-hierarchies, atmospheric-mixing octants, and CP-odd phases, three key milestones of the experimental neutrino physics program. Additionally, if the CPT-symmetry is violated in nature in a way that is consistent with all present neutrino and antineutrino oscillation data, we find that DUNE and Hyper-Kamiokande have the potential to ultimately establish leptonic CPT-invariance violation.