Dark side of the seesaw
Ivo de Medeiros Varzielas (CFTP - IST Lisbon)
I will explore the idea of connecting the dark matter sector with a sector of the Standard Model (SM), namely the neutrino sector. To do this, I consider the extension of the SM with right-handed (gauge singlet) neutrinos, which will lead to a type-I seesaw mechanism. Then I also add a fermion (another gauge singlet) dark matter candidate. To make the connection between the two sectors I finally add a scalar field mediator, whose vacuum expectation value will generate the mass for the dark matter candidate, and also take part in the generation of the neutrino mass. A Z_4 symmetry allows me to establish this framework, with the vacuum expectation value of the mediator field breaking this Z_4 to a remnant Z_2 responsible to keep dark matter stable. The observed light neutrino masses and relic abundance constraint on the dark matter allows the prediction of the heavy seesaw scale as I will illustrate in the talk. The methodology to connect dark matter and neutrino sectors introduced here is generic and can be applied to other possible neutrino mass generation mechanisms and different dark matter candidate(s).