Hierarchy and Octant determination potential of LBNE and LBNO

Abstract

Recent measurement of a moderately large value of θ 13 is very good news for both current and future long-baseline experiments. It enables them to address the outstanding issues in neutrino oscillation physics: (a) Neutrino mass hierarchy, (b) Octant of θ 23 and (c) CP violation. The current experiments, T2K and NOνA, can only give 90% C.L. hint of hierarchy and 95% hint of octant. Future facilities are imperative for making measurements at 3σ level or better. We compare the physics reach of two future superbeam facilities, LBNE and LBNO in their first phases of run, to resolve the above issues. LBNO, by itself, can determine the hierarchy at more than 10σ , even for the lowest allowed value of sin 2 θ 23 (true) = 0.34. For LBNE, the hierarchy reach is more modest. In particular, LBNE, by itself, will not be able to reach 3σ hierarchy determination, for the most unfavourable values of δ CP. The sensitivities of these future facilities improve significantly with the addition of the projected data from T2K and NOνA. Thus, LBNE is able to achieve better than 3σ hierarchy determination in combination with T2K and NOνA. The addition of T2K and NOνA data also leads to (a) significant boost in the CP violation discovery and (b) a 3σ octant resolution for sin 2 θ 23 (true) ≤ 0.44 or for sin 2 θ 23 (true) ≥ 0.58 for all values of δ CP (true) for both LBNE and LBNO.

On the determination of the $\theta_{23}$ octant in long baseline neutrino experiments

“…The question has been investigated in several other publications recently, e.g. in [17][18][19][20][21][22][23][24][25][26][27][28][29][30]. Running θ 23 around 45 o , we investigated in our study [11] the parameter range outside which the first and second octant solutions can be distinguished as a function of a given confidence limit.…”

Optimizing the θ 23 octant search in long baseline neutrino experiments

“…The question has been investigated in several other publications recently, e.g. in [17][18][19][20][21][22][23][24][25][26][27][28][29][30].…”