Speaker
Description
The latest data of the two long-baseline accelerator experiments NOνA and T2K, interpreted in the standard 3-flavor scenario, display a discrepancy. A mismatch in the determination of the standard CP-phase $\delta_{CP}$ extracted by the two experiments is evident in the normal neutrino mass ordering. While NOνA prefers values close to $\delta_{CP}$ ∼ $0.8\pi$, T2K identifies values of $\delta_{CP}$ ∼ 1.4$\pi$. Such two estimates are in disagreement at more than 90% C.L. for 2 degrees of freedom. We show that such a tension can be resolved if one hypothesizes the existence of complex neutral-current non-standard interactions (NSI) of the flavor changing type involving the $e − \mu$ or the $e − \tau$ sectors with couplings $|\varepsilon_{e\mu}|$ ∼ $|\varepsilon_{e\tau}|$ ∼ 0.2. Remarkably, in the presence of such NSI, both experiments point towards the same common value of the standard CP-phase $\delta_{CP}$ ∼ $3\pi/2$. Our analysis also
highlights an intriguing preference for maximal CP-violation in the non-standard sector with the NSI CP-phases having best fit close to $\phi_{e\mu}$ ∼ $\phi_{e\tau}$ ∼ $3\pi/2$, hence pointing towards imaginary NSI couplings.
| Working group | WG1 |
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