## Neutrinos, Lepton Number Violation and the Baryon Asymmetry of the Universe

Who: Heinrich Paes (Dortmund)
When: Monday, December 5, 2016 at 14:15
Where: The CP³ meeting room

Neutrino masses are often understood as a consequence of the breaking of lepton number, leading to a rich phenomenology of beyond the Standard Model processes, including neutrinoless double beta decay, collider processes and effects on the Baryon Asymmetry of the Universe. Such global symmetries are usually expected to be broken by quantum gravity effects, and arise in many GUT models.
Even if lepton number is conserved, however, the existence of neutrino masses requires the Standard Model to be extended.
The question whether lepton number is conserved or vioated is thus at the core of the link between neutrino masses and physics beyond the Standard Model.
Moreover, neutrinoless double beta decay, lepton number violating collider processes and the Baryon Asymmetry of the Universe (BAU) are intimately related. In particular lepton number violating processes at low energies in combination with sphaleron transitions will typically erase any pre-existing baryon asymmetry of the Universe. In this talk we discuss the importance of lepton number violation and these tight connections between neutrinoless double beta decay, lepton number violating processes at the LHC and constraints from successful baryogenesis.