Baryogenesis from gravitational decay of TeV particles in theories with low scale gravity

In models with the fundamental gravity scale in the TeV range, early cosmology is quite different from the standard picture, because the universe must have arisen at a much lower temperature and the electroweak symmetry was probably never restored. In this context, baryogenesis appears to be problematic: if the physics involved is essentially that of the standard model, ‘conventional’ non-conserving baryon number processes are completely negligible at such low temperatures. In this paper we show that the observed matter–antimatter asymmetry of the universe may be generated by gravitational decay of TeV mass particles: such objects can be out of equilibrium after inflation and, if their mass is of the same order of magnitude as the true quantum gravity scale, they can quickly decay through a black hole intermediate state, violating global symmetries, in particular, baryon number. In this context, we take advantage of the fact that the ‘Sakharov conditions’ for baryogenesis can be more easily satisfied with a low fundamental scale of gravity.