Anisotropic Lorentz invariance violation in reactor neutrino experiments

Recent reactor neutrino oscillation experiments reported precision measurements of ${\sin }^{2}2{\theta }_{13}$ and $\mathrm{\Delta }{m}_{ee}^2$ under the standard 3$\nu$ oscillation framework. However, inter-experiment consistency checks through the parameter goodness-of-fit test reveal proximity to the tension boundary, with the Double Chooz, RENO, and Daya Bay ensemble yielding $p_{\text{PG}}=0.14$ vs threshold $\alpha =0.1$. Anisotropic Lorentz invariance violation (LIV) can accommodate this tension by introducing a location-dependent angle ${\theta }^{\text{LIV}}$ relative to the earth’s axis. It is found that anisotropic LIV improve the fit to data up to 1.9$\sigma$ confidence level significance, with the coefficient ${\mathcal{A}}_{31}^{C(0)}=2.43\times {10}^{-17}\text{ MeV}$ yielding the best fit, while Parameter Goodness-of-fit (PG) is significantly improved within the LIV formalism.