Effects of BSMs on $theta_{23}$ determination

We investigate the prospects for determining the octant of $theta_{23}$ in the future long baseline oscillation experiments. We present our results as contour plots on the ($theta_{23}-45^circ$, $delta$)--plane, where $delta$ is the CP phase, showing the true values of $theta_{23}$ for which the octant can be experimentally determined at 3$,sigma$, 2$,sigma$ and 1$,sigma$ confidence level, in particular, the impact of the non-unitarity of neutrino mixing.