Enhancing the Sensitivities to Standard Unknowns in Neutrino Oscillation Framework Using High-Energy Beams at DUNE

Abstract

AbstractEven though neutrino oscillations have been conclusively established, there are a few unanswered questions pertaining to leptonic Charge Parity violation (CPV), mass hierarchy (MH) and \(\theta _{23}\) octant degeneracy. Addressing these questions is of paramount importance in the current and future neutrino experiments including the Deep Underground Neutrino Experiment (DUNE) which has a baseline of 1300 km. In the standard mode, DUNE is expected to run with a low-energy (LE) tuned beam which peaks around the first oscillation maximum (2–3 GeV) (and then sharply falls off as we go to higher energies). However, the wideband nature of the beam available at long-baseline neutrino facility (LBNF) allows for the flexibility in utilizing beam tunes that are well suited at higher energies as well. In this work, we utilize a beam that provides high statistics at higher energies which is referred to as the medium-energy (ME) beam. This opens up the possibility of exploring not only the usual oscillation channels but also the \(\nu _{\mu } \rightarrow \nu _{\tau }\) oscillation channel which was otherwise not accessible. Our goal is to find an optimal combination of beam tune and runtime (with the total runtime held fixed) distributed in neutrino and antineutrino mode that leads to an improvement in the sensitivities of these parameters at DUNE. In our analysis, we incorporate all the three channels (\(\nu _{\mu } \rightarrow \nu _{e}, \nu _{\mu } \rightarrow \nu _{\mu }, \nu _{\mu } \rightarrow \nu _{\tau }\)) and develop an understanding of their relative contributions in sensitivities at the level of \(\Delta \chi ^2\). Finally, we obtain the preferred combination of runtime using both the beam tunes as well as neutrino and antineutrino modes that lead to enhanced sensitivity to the current unknowns in neutrino oscillation physics, i.e. CPV, MH and \(\theta _{23}\) octant.