Seesaw mechanism at electron-electron colliders

Understand

We consider the Standard Model with right-handed neutrinos to explain the masses of active neutrinos by the seesaw mechanism.

• Since active neutrinos as well as heavy neutral leptons are Majorana fermions in this case, the lepton number violating process can be induced.
• We discuss the inverse neutrinoless double beta decay $e^- e^- \to W^- W^-$ in the framework of the seesaw mechanism and its detectability at future colliders.
• It is shown that the cross section can be 17 fb for $\sqrt{s}=3$ TeV even with the stringent constraint from the neutrinoless double beta decays if three (or more) right-handed neutrinos exist.