Single field baryogenesis.

We propose a new variant of the Affleck-Dine baryogenesis mechanism in which a rolling scalar field couples directly to left- and right-handed neutrinos, generating a Dirac mass term through neutrino Yukawa interactions. In this setup, there are no explicitly CP violating couplings in the Lagrangian. The rolling scalar field is also taken to be uncharged under the B - L quantum numbers. During the phase of rolling, scalar field decays generate a nonvanishing number density of left-handed neutrinos, which then induce a net baryon number density via electroweak sphaleron transitions.