Neutrino masses, leptogenesis and dark matter

Abstract: Despite the lack of evidence of new physics at colliders, neutrino masses, dark matter and matter-antimatter asymmetry of the universe require an extension of the Standard Model. After discussing some new concepts and tools in the description of seesaw neutrino models, such as motion in flavour lepton space and the introduction of the bridging matrix that nicely complements the orthogonal matrix, I discuss recent developments in the connections between neutrino data and scenarios of leptogenesis within some well motivated extensions of the Standard Model. Finally, I briefly review a simple unified picture of neutrino masses, leptogenesis and dark matter based on an extension of the seesaw Lagrangian where a non-renormalizable effective operator coupling right-handed neutrinos to the Higgs is introduced. This operator enhances the right-handed neutrino mixing between a coupled heavy right-handed neutrino and a decoupled one playing the role of dark matter. Interference between the two coupled RH neutrinos generate usual $C!P$ violation so that one can also achieve successful leptogenesis. Although the dark matter right-handed neutrino escapes direct and collider searches, its decays produce a detectable contribution to the very high energy neutrino flux now discovered by IceCube, so that the model is predictive and can be tested at neutrino telescopes.