Resolving the NO$\nu$A and T2K tension in the presence of Neutrino Non-Standard interactions

Abstract

The current data of the two long-baseline accelerator experiments NO$\nu$A and T2K, shows a tension at more than 90$\%$ C.L. for 2 degrees of freedom, in the determination of the standard CP-phase ${\delta }_{\mathrm{CP}}$ in case of neutrino normal ordering (NO). NO$\nu$A measures the value close to ${\delta }_{\mathrm{CP}}\sim 0.8\pi$, while T2K prefers the value of ${\delta }_{\mathrm{CP}}\sim 1.4\pi$. We show that such a tension can be resolved if one hypothesizes the existence of neutral-current non-standard interactions (NSI) of neutrinos involving the flavor changing type $e-\mu$ or the $e-\tau$ sectors with couplings $|{\epsilon }_{e\mu }|\sim |{\epsilon }_{e\tau }|\sim 0.2$. Remarkably, our analyses show that in the presence of such NSI, both the experiments point towards the same common value of the standard CP-phase ${\delta }_{\mathrm{CP}}\sim 3\pi /2$, thereby indicating towards the maximal CP-violation in the standard $3\nu$ framework. We also show that the best fit values of the new CP-phases ${\varphi }_{e\mu }$ or ${\varphi }_{e\tau }$ are close to $\sim 3\pi /2$, hence pointing towards the maximal CP-violation in the NSI sector.

Comments: Contribution to The 22nd International Workshop on Neutrinos from Accelerators (NuFact2021)