BARYOGENESIS IN A BARYON-SYMMETRIC UNIVERSE

Baryon number is conserved in all interactions probed by present-day experiments. If baryon number is strictly conserved then currently popular scenarios for baryogenesis will have to be reexamined. We discuss a new paradigm for baryogenesis in which the fundamental Lagrangian is baryon conserving [invariant under U(1)B]. At high temperatures, U(1)B is spontaneously broken and an excess of quarks over antiquarks of 10-10s sentropy density is produced. Today, U(1)B is restored. The most striking consequence of our assumptions is that the baryon number of the Universe is constant. During spontaneous symmetry breaking, the excess of baryons over anti-baryons in the quark fields is exactly compensated by antibaryons hidden in the vacuum. Today, antibaryons appear either as massive U(1)B charged scalar particles or as stable, nontopological bubbles of antimatter. One intriguing possibility suggested by our scenario is that the dark matter may be antimatter. © 1990 The American Physical Society.