The Neutrino Magnetic Moment Portal: Phenomenology and UV Completions

Sterile neutrinos are well-motivated extension of the Standard Model. In this seminar I will focus on the interaction between sterile neutrinos and light active neutrinos through the magnetic moment portal. I will start by showing how such interaction can be tested at neutrino and dark matter experiments such as Borexino and XENONnT, respectively. Then I will demonstrate that competitive constraints can be derived from stellar cooling arguments. Such values of the interaction strength can be realized within TeV-scale leptoquark models that can simultaneously address flavor anomalies and the muon $g-2$. However, such models also need to involve tuning or additional symmetries in order not to generate unacceptably large contribution to the active neutrino mass. This problem is naturally resolved for a couple of orders of magnitude smaller values of the magnetic moment and such interaction strengths are indeed reachable in light of BBN, CMB and supernova probes. In particular, I will show that strong constraints can be derived from SN1987A through the non-observation of active neutrinos and photons produced from sterile neutrino decays. Finally, sensitivity projections for several present and near-future experiments such as Fermi-LAT, e-ASTROGAM, DUNE and Hyper-Kamiokande will be shown for the future galactic supernova event.