We consider generic neutrino dipole portals between left-handed neutrinos, photons, and right-handed heavy neutral leptons (HNL) with Dirac masses. The dominance of this portal significantly alters the conventional phenomenology of HNLs. We derive a comprehensive set of constraints on the dipole portal to HNLs by utilizing data from LEP, LHC, MiniBooNE, LSND as well as observations of Supernova 1987A and consistency of the standard big bang nucleosynthesis. We calculate projected sensitivities from the proposed high-intensity SHiP beam dump experiment, and the ongoing experiments at the Short-Baseline Neutrino facility at Fermilab. Dipole mediated Primakoff neutrino upscattering and Dalitz-like meson decays are found to be the main production mechanisms in most of the parametric regime under consideration. Proposed explanations of LSND and MiniBooNE anomalies based on HNLs with dipole-induced decays are found to be severely constrained, or to be tested in the future experiments.
Bibliographical noteFunding Information:
We thank Ornella Palamara, Roni Harnik, and Zarko Pavlovic for the correspondence and for the details of the experiments along the Booster Neutrino Beamline at Fermilab. We also thank Jae Hyeok Chang and Robert Lasenby for useful references in astrophysical and cosmological constraints, and Jonah Miller for discussions relating to supernova simulations. In addition, we thank Cliff Burgess, Pilar Hernandez, Richard Hill, Joseph Bramante, and Christopher Brust for useful discussions. This research was supported in part by Perimeter Institute for Theoretical Physics. Research at Perimeter Institute is supported by the Government of Canada through the Department of Innovation, Science and Economic Development and by the Province of Ontario through the Ministry of Research and Innovation. This research was also supported by funds from the National Science and Engineering Research Council of Canada (NSERC), and the Ontario Graduate Scholarship (OGS) program. Y. T. was supported by the Visiting Graduate Fellow program at Perimeter Institute.
© 2018 authors. Published by the American Physical Society.