Leptogenesis via Collisions: Leaking Lepton Number to the Hidden Sector

Abstract

We propose a lepto-baryogenesis mechanism in which the non-zero B-L of the universe is produced in out-of-equilibrium, lepton number and CP violating scattering processes that convert ordinary particles into particles of some hidden sector. In particular, we consider the processes $l\varphi >l^{\prime }{\varphi }^{\prime },{\bar{l}}^{\prime }\bar{p}h{i}^{\prime }$ mediated by the heavy Majorana neutrinos $N$ of the seesaw mechanism, where $l$ and $\varphi$ are ordinary lepton and Higgs doublets and $l^{\prime }$, ${\varphi }^{\prime }$ their hidden counterparts. Such a leptogenesis mechanism is effective even if the reheating temperature is much smaller than the heavy neutrino masses. In particular, it can be as low as $10^9$ GeV.

Comments: 4 pages, revtex, 2 figures; as to appear in PRL, supplemented with an additional remark