Leptogenesis at the TeV scale

We present a general description of the problems encountered when attempting to build a simple model of leptogenesis and hence of baryogenesis at an energy scale as low as 1-10 TeV. We consider three possible lepton asymmetry enhancement mechanisms in the out-of-equilibrium decay scenario, emphasizing the three body decay mechanism as most natural. A new model based on the three body decays of right-handed neutrinos is proposed. It naturally allows both leptogenesis and neutrino mass generation at low scale. Also discussed is the possibility of inducing leptogenesis at low scale in existing neutrino mass models: Fukugita-Yanagida model, Higgs triplet model, Zee model and models with R-parity violation. (C) 2002 Elsevier Science B.V. All rights reserved.