Leptogenesis and composite heavy neutrinos with gauge-mediated interactions

Leptogenesis is an appealing framework to account for the baryon asymmetry in the universe. To this end physics beyond the standard model is demanded. In this paper we investigate the possibility to attain successful lepto- genesis with composite Majorana neutrinos. We work in the framework of effective gauge-mediated and contact inter- actions without any reference to an underlying composite- ness theory. This approach is the one adopted in all current experimental searches for composite fermions at colliders. In the case of gauge-mediated interactions, we calculate the CP asymmetry in heavy composite neutrino decays. Both the direct and the indirect CP asymmetry are derived and reso- nant leptogenesis is also discussed. We find that the Sakharov conditions can be met and, for some choice of the parame- ters, the correct order of magnitude of the baryon asymmetry is reproduced.