Stochastic Baryogenesis

Abstract

Using a multi-field stochastic approach, we investigate the vacuum expectation value (VEV) during inflation of a scalar field charged under a mildly broken global $U(1)$ symmetry that can play the role of baryon or lepton number, or possibly a dark baryon number or a combination of the three. Even for a CP invariant Lagrangian, the stochastic distribution of inflationary VEVs in general breaks CP spontaneously, allowing for successful baryogenesis via the Affleck-Dine mechanism. For the Hubble scale during inflation $H_{\ast }$ as high as $10^{13}$ GeV, we show that the post-inflationary relaxation of the charged scalar with stochastic initial conditions can explain the observed baryon asymmetry, and that a charged scalar mass at the order of $H_{\ast }$ is favored by the isocurvature constraints.

Comments: 26 pages, 8 figures, Figure 8 replaced, included comments on supersymmetric and slow-roll inflation scenarios, version matched with publication