Constraining active-sterile neutrino transition magnetic moments at DUNE near and far detectors

TL;DR

This paper evaluates DUNE's potential to detect heavy neutral leptons with transition magnetic moments via single-photon signals, expanding the search for sterile neutrinos in the MeV to GeV range.

Contribution

It demonstrates DUNE's capability to probe the dipole portal of sterile neutrinos, especially tau-neutrino interactions, and compares its sensitivity to other experiments.

Findings

DUNE can explore large unconstrained parameter space for sterile neutrinos.

Far detector is sensitive to tau-neutrino dipole interactions.

Near detector provides better sensitivity to electron and muon neutrino dipole interactions.

Abstract

We consider the sensitivity of the DUNE experiment to a heavy neutral lepton, HNL (also known as sterile neutrino) in the mass range from a few MeV to a few GeV, interacting with the Standard Model via a transition magnetic moment to the active neutrinos, the so-called dipole portal. The HNL is produced via the upscattering of active neutrinos, and the subsequent decay inside the detector provides a single-photon signal. We show that the tau-neutrino dipole portal can be efficiently probed at the DUNE far detector, using the tau-neutrino flux generated by neutrino oscillations, while the near detector provides better sensitivity to the electron- and muon-neutrino dipole portal. DUNE will be able to explore large regions of currently unconstrained parameter space and has comparable sensitivity to other planned dedicated experiments, such as SHiP. We also comment briefly on the sensitivity to pure HNL mixing with the tau neutrino at the DUNE far detector.