Neutrino Mass Hierarchy and Neutrino Oscillation Parameters with One Hundred Thousand Reactor Events

Abstract High-statistics reactor neutrino experiments at medium baselines will probe mass-mixing parameters governing neutrino oscillations at long wavelength, driven by the ( δm 2 , θ 12 ) and at short wavelength, driven by (Δ m 2 , θ 13 ).The interference between these two oscillations will allow to probe the mass hierarchy. The determination of the neutrino mass spectrum hierarchy, however, will require an unprecedented level of detector performance and collected statistics, and the control of several systematics at (sub)percent level. In this work we perform accurate theoretical calculations of reactor event spectra and refined statistical analyses to show that with O (10 5 ) reactor events, a typical sensitivity of ∼ 2 σ could be achieved by an experiment such as JUNO. We also show the impact of the energy scale and spectrum shape systematics on the determination of the hierarchy.