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Multi-messenger probes of the nature of neutrino mass

by Bhupal Dev (Washington University in St. Louis)


Whether neutrinos are Majorana or Dirac particles is an open question. Theoretically, it is also possible that neutrinos are pseudo-Dirac, which are fundamentally Majorana fermions, but essentially act like Dirac fermions in most experimental settings, due to small active-sterile mass splitting. Such small values of mass splitting can only be accessed via active-sterile oscillations over an astrophysical baseline, or via decays of neutrinos over a cosmological time scale. In this talk, we will use the multi-messenger observation of high-energy neutrino sources and the excess extragalactic radio background to probe two different regimes of the pseudo-Dirac neutrino parameter space.