APEC Seminar (Astronomy - Particle Physics - Experimental Physics - Cosmology)

Speaker: Kai Schmitz (University of Padova and INFN)
Title: Low-Scale Leptogenesis beyond the Type-I Seesaw
Date: Wed, Jul 17, 2019, 13:30 - 14:30
Place: Seminar Room A
Related File: 2359.pdf
Abstract: Leptogenesis in the type-I seesaw model offers an attractive possibility to explain the baryon asymmetry of the Universe. However, in its standard formulation, thermal leptogenesis requires a spectrum of hierarchical right-handed neutrinos (RHNs) with masses in the EeV range.
This makes it hard to probe this scenario experimentally and aggravates the electroweak hierarchy problem because of large radiative corrections to the Higgs boson mass. In my talk, I will therefore discuss three simple modifications of the standard type-I seesaw setup that allow one to lower the RHN mass scale to (much) smaller values. Specifically, I will consider leptogenesis (1) in the type-I seesaw model with classically scale-invariant boundary conditions in the Higgs sector, (2) in Ernest Ma's scotogenic model, and (3) in the scalar-singlet extension of the Standard Model. As I will demonstrate, these models lead to successful leptogenesis at RHN masses of O(10) PeV, O(10) TeV, and
O(100) GeV, respectively. In addition, they imply various interesting connections between the RHN sector and the physics of other sectors, such as the Standard Model Higgs sector or the sector of dark matter, which can be tested in experiments. My talk will be based on 1804.09660, 1812.04421, and 1905.12634.