Neutrino Parameters from Reactor and Accelerator Neutrino Experiments

We revisit correlations of neutrino oscillation parameters in reactor and long-baseline neutrino oscillation experiments. A framework based on an effective value of ${\theta }_{13}$ is presented, which can easily reproduce experimental results. It also clarifies why current and future long-baseline experiments will have less precision on values around ${\delta }_{CP}=\pm \pi \mathrm{/}2$ than on values around ${\delta }_{CP}=0$. Optimization potential for the determination of the theoretically very interesting values around $\delta_{CP} = -\pi/2$ is also pointed out, which would require that future runs of accelerator experiments are not equally shared $1:1$ in neutrino and antineutrino modes, but rather $2:1$. Recent hints on the CP phase and the mass ordering are then considered from the point of view that different reactor and long-baseline neutrino experiments provide currently different best-fit values of ${\theta }_{13}$ and ${\theta }_{23}$. We point out that the significance of the hints changes for the different available best-fit values.