Baryogenesis from gravitational decay of TeV particles in theories with low scalegravity

Abstract

In models with the fundamental gravity scale in the TeV range, early cosmology is quitedifferent from the standard picture, because the universe must have arisen at a muchlower temperature and the electroweak symmetry was probably never restored. Inthis context, baryogenesis appears to be problematic: if the physics involved isessentially that of the standard model, ‘conventional’ non-conserving baryon numberprocesses are completely negligible at such low temperatures. In this paper weshow that the observed matter–antimatter asymmetry of the universe may begenerated by gravitational decay of TeV mass particles: such objects can be out ofequilibrium after inflation and, if their mass is of the same order of magnitude asthe true quantum gravity scale, they can quickly decay through a black holeintermediate 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 ofgravity.