Interplay of CPT-violating and CPT-conserving Lorentz invariance violation at DUNE

A bstract We present a study of Lorentz invariance violation (LIV) in neutrino oscillations, with primary emphasis on the interplay between CPT-violating and CPT-conserving Standard Model Extension (SME) coefficients. We find that a ee and a ττ dominate among the diagonal LIV coefficients, whereas a eμ and a eτ provide the most significant off-diagonal contributions. In contrast, the corresponding c αβ coefficients have comparatively sub-leading effects. Taking DUNE as a representative long-baseline experiment, we show that the sensitivity to CP violation is modified by LIV in a parameter-specific manner. We find correlations between off-diagonal LIV parameters, and non-trivial dependence on the new phases. In absence of LIV, DUNE is expected to establish CP violation at 5 σ for a limited fraction of δ CP values. We find that the presence of a ee , a ττ , a eμ and a eτ weakens the CP discovery potential, reducing the achievable significance to below 3 σ over a substantial fraction of δ CP . The independent impact of c αβ terms also results in suppression, but in combination with a αβ , they introduce degeneracies, complicating the extraction of δ CP . This generally results in a deterioration of CP violation sensitivities below 5 σ . These findings emphasize the importance of incorporating LIV effects in precision oscillation studies at upcoming long-baseline experiments.