Leptonic first-row correlation and unitarity waiting for further JUNO tests

Abstract

We conjecture that there exists a remarkable correlation among the three elements in the first row of the $3\times 3$ lepton flavor mixing matrix $U$: $|U_{e1}^{}{|}^2=2\left(|U_{e2}^{}{|}^2+|U_{e3}^{}{|}^2\right)$, which holds even though $U$ is non-unitary in the canonical seesaw mechanism. This ``first-row correlation" is fully consistent with ${\sin }^2{\theta }_{12}^{}=\left(1-2{\tan }^2{\theta }_{13}^{}\right)/3$ in the unitarity limit of $U$, as supported by the latest JUNO and Daya Bay precision measurements at a confidence level close to $1\sigma$.

LaTeX 10 pages, 2 figures. Revised and shortened version (accepted for publication in Science Bulletin as a Short Communication)