Discovery-HET Seminar: Jim Cline (McGill)

Speaker: Jim Cline (McGill)

Title: Constrained Flavor Violation

Abstract: Recently it was suggested (1503.07450) that the Yukawa matrix for down quarks could be determined by those for up quark and charged leptons through the relation Y_d ~ Y_u Y_e^dagger.  If true, it would be an important hint for building a more fundamental theory of flavor.  I will show that it is difficult (though perhaps still possible) to reconcile this ansatz with the measured lepton masses.  Accepting the slim possibility that it is viable, I then extend the framework to include neutrino Yukawa couplings, arguing that Y_nu ~ Y_e Y_u^dagger is the most natural option.  We study leptogenesis in this framework, showing that it is constrained but can with reasonable probability give the observed baryon asymmetry.  It provides an example of "N_2 leptogenesis," where the dominant contributions come from decays of the next-to-lightest right-handed neutrinos.