Chasing $\theta_{13}$ with new reactor neutrino experiments

TL;DR

New reactor neutrino experiments with multiple detectors at medium baselines aim to precisely measure the  mixing angle , improving sensitivity and potentially discovering -related phenomena beyond current constraints.

Contribution

The paper reviews proposed reactor neutrino experiments designed to measure  with higher sensitivity, highlighting their potential to improve current bounds and resolve parameter degeneracies.

Findings

Projected sensitivities range from  angle measurements of  < 0.01 to 0.03.

Multiple experimental proposals worldwide with different timelines.

Potential to significantly advance understanding of  mixing.

Abstract

It is now widely accepted that a new middle baseline disappearance reactor neutrino experiment with multiple detectors could provide a clean measurement of the $\theta_{13}$ mixing angle, free from any parameter degeneracies and correlations induced by matter effect and the unknown leptonic Dirac CP phase. The current best constraint on the third mixing angle comes from the Chooz reactor neutrino experiment $\sin^{2}(2\theta_{13})<0.2$ (90$ %$ C.L., $\Delta m_{\rm atm}^{2}=2.0 10^{-3}$ eV$^{2}$). Several projects of experiment, with different timescales, have been proposed over the last two years all around the world. Their sensitivities range from $\sin^{2}(2\theta_{13})<$ 0.01 to 0.03, having thus an excellent discovery potential of the $\nu_e$ fraction of $\nu_3$.