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

UNSPECIFIED (2026) Sensitivity of the Hyper-Kamiokande experiment to neutrino oscillation parameters using accelerator neutrinos. European Physical Journal C, 86 (2): 170. ISSN 1434-6044

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Abstract

This paper describes the analysis to estimate the sensitivity of the Hyper-Kamiokande experiment to long-baseline neutrino oscillation parameters using accelerator (anti)neutrinos. Results are presented for the CPV discovery sensitivity and precision measurements of the oscillation parameters $\delta_{CP}$, $\sin^2\theta_{23}$, $\Delta m^2_{32}$ and $\sin^2\theta_{13}$. With the assumed Hyper-Kamiokande running plan, a $5\sigma$ CPV discovery is possible in less than three years in the case of maximal CPV and known MO.In the absence of external constraints on the MO, considering the MO sensitivity of the Hyper-Kamiokande measurement using atmospheric neutrinos, the time for a CPV discovery could be estimated to be around six years. Using the nominal final exposure of $27 \times 10^{21}$ protons on target, corresponding to 10 years, with a ratio of 1:3 in neutrino to antineutrino beam mode, we expect to select approximately 10000 charged current, quasi-elastic-like, muon neutrino events, and a similar number of muon anti-neutrino events. In the electron (anti)neutrino appearance channels, we expect approximately 2000 charged current, quasi-elastic-like electron neutrino events and 800 electron antineutrino events. These larges event samples will allow Hyper-Kamiokande to exclude CP conservation at the $5\sigma$significance level for over 60% of the possible true values of $\delta_{CP}$.