Baryogenesis, dark matter and the width of the Z

Abstract

We discuss a paradigm in which the generation of the observed quark-antiquark asymmetry is directly related to the origin of dark matter. In particular we consider a baryon-number conserving extension of the standard model by the addition of a weak isotriplet U(1) B -charged scalar field φ. We describe a scenario in which the out-of-equilibrium decay of heavy scalar particles preferentially produces quarks over antiquarks leading to the observed asymmetry. The excess baryon-number in the quark fields is exactly compensated by a net antibaryon-number in φ-particles. We focus on the consequences for both particle physics and cosmology and show that the mass of φ is very tightly constrained: 40 GeV ⪅ m φ ⪅50 GeV. We discuss accelerator signatures, the interaction of φ's with ordinary matter and implications for gf-particle detection. Finally we discuss some interesting cosmological phase transitions involving both U(1) B and the electroweak symmetry.