Sensitivity of the Hyper-Kamiokande experiment to neutrino oscillation parameters using accelerator neutrinos

Abstract This paper presents the expected sensitivity to the neutrino oscillation parameters of the Hyper-Kamiokande long-baseline program. The Hyper-Kamiokande experiment, currently under construction in Japan, will measure the oscillations of accelerator-produced neutrinos with thousands of selected events per sample: this corresponds to an increase of statistics of a factor 25–100 with respect to recent results from the currently-running long-baseline neutrino oscillation experiment in Japan, T2K. In the most favorable scenario we will achieve the discovery of Charge-Parity (CP) violation in neutrino oscillation at $$5\sigma $$ 5 σ C.L. in less than 3 years. With 10 years of data-taking, and assuming a neutrino : antineutrino beam running ratio of 1:3, a CP violation discovery at $$5\sigma $$ 5 σ C.L. is possible for more than 60% of the actual values of the CP-violating phase, $$\delta _{CP}.$$ δ CP . Moreover, we will measure $$\delta _{CP}$$ δ CP with a precision ranging from 20 $$^{\circ },$$ ∘ , in the case of maximal CP violation, to 6 $$^{\circ },$$ ∘ , in the case of CP conservation. We aim to achieve a 0.5% resolution on the $$\Delta m^2_{32}$$ Δ m 32 2 parameter, and a resolution between 3% and 0.5% on the $$\sin ^2\theta _{23}$$ sin 2 θ 23 parameter, depending on its true value. These results are obtained by extending the analysis methods of T2K with dedicated tuning to take into account the Hyper-Kamiokande design: the larger far detector, the more powerful beam, the upgraded near detector ND280, and the planned additional Intermediate Water Cherenkov Detector.