Radiative decay of heavy neutrinos at MiniBooNE and MicroBooNE

TL;DR

This paper investigates the potential role of radiative decay of heavy sterile neutrinos in explaining MiniBooNE's low-energy excess, analyzing production and decay mechanisms at MiniBooNE and MicroBooNE detectors.

Contribution

It provides a detailed analysis of heavy neutrino production and decay, proposing a testable explanation for the MiniBooNE anomaly based on radiative decay signatures.

Findings

Photon emission distributions suggest detectable signals at MicroBooNE.

Production mechanisms include coherent and incoherent electroweak interactions.

The model predicts distinctive photon event shapes and counts.

Abstract

The MiniBooNE experiment reported results from the analysis of $\nu_e$ and $\overline{\nu}_e$ appearance searches, which showed an excess of signal-like events at low reconstructed neutrino energies with respect to the expected background. A proposed explanation for this anomaly is based on the existence of a heavy ($\sim 50$~MeV) sterile neutrino. These $\nu_h$ would be produced by $\nu_\mu$ electromagnetic and neutral current interactions. A fraction of them decays radiatively inside the detector. The emitted photon is misidentified as an electron or positron in MiniBooNE. We have investigated the $\nu_h$ production by coherent and incoherent electroweak interactions at the MiniBooNE and MicroBooNE targets, CH$_2$ and Ar, respectively. Studying the $\nu_h$ propagation inside the detector, we obtain the energy and angular distributions of emitted photons for a choice of model parameters. The distinctive shape and total number of photon events from this mechanism at MicroBooNE makes its experimental investigation possible.