Sizable NSI from the $SU(2)_L$ scalar doublet-singlet mixing and the implications in DUNE

TL;DR

This paper introduces a new mechanism where mixing between a second Higgs doublet and a charged singlet induces significant non-standard neutrino interactions, which can mimic CP effects but are distinguishable in future experiments like DUNE.

Contribution

It proposes a novel scalar mixing mechanism that produces sizable NSI effects in neutrino propagation, with potential implications for future neutrino experiments.

Findings

Sizable NSI $ ilde{ u}_{e au}$ can reach $ ext{~}0.3$ without experimental exclusion.

NSI effects can mimic Dirac CP phase effects in neutrino oscillations.

Future experiments like DUNE can disentangle NSI from standard CP effects.

Abstract

We propose a novel and simple mechanism where sizable effects of non-standard interactions (NSI) in neutrino propagation are induced from the mixing between an electrophilic second Higgs doublet and a charged singlet. The mixing arises from a dimensionful coupling of the scalar doublet and singlet to the standard model Higgs boson. In light of the small mass, the light mass eigenstate from the doublet-singlet mixing can generate much larger NSI than those induced by the heavy eigenstate. We show that a sizable NSI $\varepsilon_{e\tau}$ ($\sim 0.3$) can be attained without being excluded by a variety of experimental constraints. Furthermore, we demonstrate that NSI can mimic effects of the Dirac CP phase in the neutrino mixing matrix but they can potentially be disentangled by future long-baseline neutrino experiments, such as the Deep Underground Neutrino Experiment (DUNE).