# Mass hierarchy and CP-phase sensitivity of ORCA using Fermilab Neutrino Beam

## TL;DR

This study assesses ORCA's capability to determine neutrino mass hierarchy and CP-phase using Fermilab's neutrino beam, showing high confidence in hierarchy detection within a year and potential CP-phase sensitivity over a decade.

## Contribution

It demonstrates the feasibility of using the ORCA detector with Fermilab's beam for precise neutrino oscillation parameter measurements, including mass hierarchy and CP-phase.

## Key findings

- Mass hierarchy can be determined at >4σ in 1 year with neutrino mode.
- Combined neutrino and antineutrino data can reach >6σ hierarchy confidence.
- CP-phase can be detected at ~1.8σ after 10 years.

## Abstract

We explore neutrino mass hierarchy determination and CP-phase measurement using multi-megaton water Cherenkov detector KM3NeT-Oscillation Research with Cosmics in the Abyss (ORCA) in the Mediterranean sea receiving neutrino beam from the Fermilab Long Baseline Neutrino Facility (LBNF) over 6900 km baseline. We find that with the proposed beam luminosity of $1.2\times 10^{21}$ proton-on-target per year, it will be possible to determine mass hierarchy at $\gtrsim 4\,\sigma$ confidence level within 1 year in the neutrino mode alone. A combined 1 year in neutrino and 1 year in antineutrino mode can determine hierarchy at $\gtrsim 6\,\sigma$ confidence level. We also find that a non-zero CP-phase can be detected with up to $\sim 1.8\,\sigma$ significance after 10 years of data taking. We explore degeneracy of neutrino oscillation parameters and uncertainties in detection efficiencies affecting the results.