Speaker
Description
We consider BSM models in which neutrinos couple to Heavy Neutral Leptons (HNLs). In these models, an incoming flux of atmospheric neutrinos can scatter off of nuclei in the Earth, producing a flux of HNLs (upscattering) with energies ranging from O(10 MeV) to O(10 GeV). If an HNL decays within a neutrino detector, it can produce a visible signal, appearing as an excess of neutrino interactions. We use a Monte Carlo simulation to model this phenomenon, and compare with data from Super-Kamiokande to place leading bounds on the dipole portal for HNL masses ~10 MeV - 100 MeV and the tau mass-mixing portal for HNL masses ~15 MeV - 30 MeV. We end by estimating the upscattering signal in the next generation of neutrino experiments and using it to place projections on future bounds.
