Catching neutrinos by the dipole (Michele Frigerio, LPTHE)
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amphi Charpak
Neutrinos may couple to the photon, via higher-dimension operators or quantum corrections. We begin by briefly reviewing the general electromagnetic properties of neutrinos. We then focus on the neutrino dipole moments, and present a couple of novel possibilities to constrain it. On the one hand, the dipole of light Majorana neutrinos violates lepton number, and thus induces a same-sign dilepton final state at colliders. We show that a future muon collider could directly observe such dipole, for values compatible with current, indirect constraints. On the other hand, heavy neutrinos, usually searched for through their mixing with light neutrinos, may also have a sizeable dipole. We show that a GeV-scale neutrino may then produce a large photon signal, e.g. in beam-dump experiments such as SHiP.