# A hybrid setup for fundamental unknowns in neutrino oscillations using T2HK (*ν*) and *μ*-DAR \( \left(\overline{\nu}\right) \)

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## Abstract

Neutrino mass hierarchy, CP-violation, and octant of *θ* _{23} are the fundamental unknowns in neutrino oscillations. In order to address all these three unknowns, we study the physics reach of a setup, where we replace the antineutrino run of T2HK with antineutrinos from muon decay at rest (*μ*-DAR). This approach has the advantages of having higher statistics in both neutrino and antineutrino modes, and lower beam-on backgrounds for antineutrino run with reduced systematics. We find that a hybrid setup consisting of T2HK (ν) and *μ*-DAR \( \left(\overline{\nu}\right) \) in conjunction with full exposure from T2K and NO*ν*A can resolve the issue of mass hierarchy at greater than 3*σ* C.L. irrespective of the choices of hierarchy, *δ* _{CP}, and *θ* _{23}. This hybrid setup can also establish the CP-violation at 5*σ* C.L. for ∼ 55% choices of *δ* _{CP}, whereas the same for conventional T2HK \( \left(\nu + \overline{\nu}\right) \) setup along with T2K and NOνA is around 30%. As far as the octant of *θ* _{23} is concerned, this hybrid setup can exclude the wrong octant at 5*σ* C.L. if *θ* _{23} is at least 3° away from maximal mixing for any *δ* _{CP}.

### Keywords

Neutrino Physics CP violation## Notes

**Open Access**

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