Constraining flavour-universal nonstandard interactions and superweak extension of the standard model

Abstract

Nonstandard neutrino interactions (NSI) arising from light and heavy mediators probe different sectors of the parameter space of models focusing on phenomena that require the extension of the standard model. High-energy scattering experiments are not relevant on constraining the NSI hiding a light mediator at the fundamental level, while flavour-universal NSI cannot be probed with neutrino oscillation experiments. Currently the only way to measure flavour-universal NSI with a light mediator is to rely on coherent elastic neutrino-nucleon scattering experiments, which we use to derive bounds for light mediator flavour-universal NSI. For light NSI, we obtain $\varepsilon^u \in [-14.85,14.79]$ and $\varepsilon^d \in [-13.19,13.84]$ (90~\% CL.). We also derive constraints on flavour-universal heavy NSI and find a 2$\sigma$ tension. Finally, we discuss the implications of the experiments on the allowed parameter space of a specific example model, called superweak extension of the standard model.