Neutrino Parameters from Reactor and Accelerator Neutrino Experiments

TL;DR

This paper analyzes correlations of neutrino oscillation parameters in reactor and accelerator experiments, introducing a framework with an effective $ heta_{13}$ to interpret experimental results and optimize future measurements of the CP phase.

Contribution

It presents a new effective parameter framework for neutrino oscillation analysis and suggests optimized experimental strategies for better CP phase determination.

Findings

Current experiments show varying best-fit values for $ heta_{13}$ and $ heta_{23}$.

Hints on CP phase and mass ordering depend on these best-fit values.

Optimized run plans could improve sensitivity around $ heta_{CP} = -rac{ ext{pi}}{2}$.

Abstract

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 $\delta_{CP} = \pm \pi/2$ 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.