Majorana vs Pseudo-Dirac Neutrinos at the ILC

Low-scale seesaw models of neutrino masses with an approximate lepton number symmetry can be tested at colliders. In the minimal Type I Seesaw model, this implies the existence of two highly degenerate heavy Majorana fermions forming a pseudo-Dirac pair. A very important question is to what extent future colliders will have sensitivity to the splitting between the Majorana components of this neutral heavy lepton, which signals the breaking of lepton number. We consider the production of these heavy leptons at the ILC, where their displaced decays provide a golden signal: a forward-backward asymmetry, which depends crucially on the mass splitting between the two Majorana components. We show that this observable can constrain the mass splitting to values much lower than current bounds, which come from neutrinoless double beta decay and loop corrections.

Año: 2018
Ciudad: Lima