Speaker
Description
The present global analyses of the oscillation data do not agree on the octant in which the best-fit value of $\theta_{23}$ lies. Further, they allow $\sin^{2}\theta_{23}=0.5$ at 3$\sigma$ confidence level. Hence, it is imperative to question at what confidence level maximal 2-3 mixing can be ruled out. We study in detail the performance of DUNE to establish the deviation from maximal $\theta_{23}$. We also discuss the impact of $\sin^{2}\theta_{23} - \Delta m^{2}_{31}$ degeneracy in establishing non-maximal $\theta_{23}$ and show how this degeneracy can be resolved by exploiting the spectral shape information in $\nu$ and $\bar{\nu}$ disappearance events. We find that a 3$\sigma$ (5$\sigma$) determination of non-maximal $\theta_{23}$ is possible in DUNE with an exposure of 336 kt$\cdot$MW$\cdot$years if the true value of $\sin^2\theta_{23} <=0.465~(0.450)$ or $\sin^2\theta_{23} >= 0.554~(0.572)$ for any value of true $\delta_{\mathrm{CP}}$ and true NMO. We also study the individual contributions from appearance and disappearance channels, the impact of systematic uncertainties, and data from both $\nu$ and $\bar\nu$ runs, while analyzing DUNE's sensitivity for the discovery of a non-maximal $\theta_{23}$.
