Status of neutrino oscillations 2018: 3σ hint for normal mass ordering and improved CP sensitivity

Abstract

We present a new global fit of neutrino oscillation parameters within the simplest three-neutrino picture, including new data which appeared since our previous analysis [1]. In this update we include new long-baseline neutrino data involving the antineutrino channel in T2K, as well as new data in the neutrino channel, data from NOνA, as well as new reactor data, such as the Daya Bay 1230 days electron antineutrino disappearance spectrum data and the 1500 live days prompt spectrum from RENO, as well as new Double Chooz data. We also include atmospheric neutrino data from the IceCube DeepCore and ANTARES neutrino telescopes and from Super-Kamiokande. Finally, we also update our solar oscillation analysis by including the 2055-day day/night spectrum from the fourth phase of the Super-Kamiokande experiment. With the new data we find a preference for the atmospheric angle in the upper octant for both neutrino mass orderings, with maximal mixing allowed at Δχ2=1.6(3.2) for normal (inverted) ordering. We also obtain a strong preference for values of the CP phase δ in the range [π,2π], excluding values close to π/2 at more than 4σ. More remarkably, our global analysis shows a hint in favor of the normal mass ordering over the inverted one at more than 3σ. We discuss in detail the status of the mass ordering, CP violation and octant sensitivities, analyzing the interplay among the different neutrino data samples. Keywords: Neutrino mass and mixing, Neutrino oscillation, Solar and atmospheric neutrinos, Reactor and accelerator neutrinos, Neutrino telescopes