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

• Published in: The journal of high energy physics 2017-05, Vol.2017 (5), p.1-19, Article 115
• Main Authors: Agarwalla, Sanjib Kumar, Ghosh, Monojit, Raut, Sushant K.
• Format: Article
• Language: English
• Subjects: CP violation; Neutrino Physics
• ISSN: 1029-8479; 1029-8479
• DOI: 10.1007/JHEP05(2017)115

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 ν ¯ $$ \left(\overline{\nu}\right) $$ in conjunction with full exposure from T2K and NOνA can resolve the issue of mass hierarchy at greater than 3σ C.L. irrespective of the choices of hierarchy, δ CP, and θ 23. This hybrid setup can also establish the CP-violation at 5σ C.L. for ∼ 55% choices of δ CP, whereas the same for conventional T2HK ν + ν ¯ $$ \left(\nu + \overline{\nu}\right) $$ 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 5σ C.L. if θ 23 is at least 3° away from maximal mixing for any δ CP.