A close look on 2-3 mixing angle with DUNE in light of current neutrino oscillation data

Abstract

Abstract Recent global fit analyses of 3ν oscillation data show a preference for normal mass ordering (NMO) at 2.5σ and provide 1.6σ indications for lower θ 23 octant (sin2 θ 23 < 0.5) and leptonic CP violation (sin δ CP < 0). In this work, we study in detail the capabilities of DUNE to establish the deviation from maximal θ 23 and to resolve its octant in light of the current data. Introducing for the first time, a bi-events plot in the plane of total ν and ν ¯ $$ \overline{\nu} $$ disappearance events, we discuss the impact of sin2 θ 23 – ∆ m 31 2 $$ {m}_{31}^2 $$ degeneracy in establishing non-maximal θ 23 and show how this degeneracy can be resolved with the help of spectral analysis. A 3σ (5σ) determination of non-maximal θ 23 is possible in DUNE with an exposure of 336 kt·MW·years if the true value of sin2 θ 23 ≲ 0.465 (0.450) or sin2 θ 23 ≳ 0.554 (0.572). We study the role of appearance and disappearance channels, systematic uncertainties, marginalization over oscillation parameters, and the importance of spectral analysis in establishing non-maximal θ 23. We observe that both ν and ν ¯ $$ \overline{\nu} $$ data are essential to settle the θ 23 octant at a high confidence level. DUNE can resolve the octant of θ 23 at 4.2σ (5σ) using 336 (480) kt·MW·years of exposure for the present best-fit values of oscillation parameters. DUNE can improve the current relative 1σ precision on sin2 θ 23 (∆ m 31 2 $$ {m}_{31}^2 $$ ) by a factor of 4.4 (2.8) using 336 kt·MW·years of exposure.

Keywords

• Neutrino Physics
• Beyond Standard Model