Novel dependence between neutrino mass splittings strongly supported by initial JUNO results

Abstract

In the standard three-flavor paradigm, two of the three neutrino mass-squared differences are independent. The existence of an additional dependence between these oscillation parameters was recently predicted on empirical grounds, taking the form $$\frac{\sqrt{\Delta m_{31}^2}+\sqrt{\Delta m_{21}^2}}{\sqrt{\Delta m_{31}^2}-\sqrt{\Delta m_{21}^2}}=\sqrt{2}.$$ The JUNO Collaboration has now reported the most precise measurements to date of both $\Delta m_{21}^2$ and $\Delta m_{31}^2$. We demonstrate that this relation is in excellent agreement with the experimental data, which yield $1.4143_{-0.0038}^{+0.0036}$ corresponding to a relative precision of $0.27\%$. Remarkably, the central value differs by less than $0.03$ standard deviations from the prediction ($\sqrt{2}\approx 1.4142$). This provides strong experimental support for the novel constraint and thereby suggests an underlying symmetry governing the neutrino mass spectrum, rather than purely independent parameters.

8 pages, 1 figure, 1 table