A bound on neutrino masses from baryogenesis

Properties of neutrinos, the lightest of all elementary particles, amy be the origin of the entire matter antimatter asymmetry of the universe. This requires that neutrinos are Majorana particles, which are equal to their antiparticles, and that their masses are sufficiently small. Leptogenesis, the theory explaining the cosmic matter antimatter asymmetric, predicts that all neutrino masses are smaller than 0.2 eV, which will be tested by forthcoming laboratory experiments and by cosmology. (C) 2002 Elsevier Science B.V. All rights reserved.