Ratchet Baryogenesis with an Analogy to the Forced Pendulum
  A new scenario of baryogenesis via the ratchet mechanism is proposed based on an analogy to the forced pendulum. The oscillation of the inflaton field during the reheating epoch after inflation plays the role of the driving force, while the phase $\theta$ of a scalar baryon field (a complex scalar field with baryon number) plays the role of the angle of the pendulum. When the inflaton is coupled to the scalar baryon, the behavior of the phase $\theta$ can be analogous to that of the angle of the forced pendulum. If the oscillation of the driving force is adjusted to the pendulum's motion, a directed rotation of the pendulum is obtained with a non-vanishing value of $\dot{\theta}$, which models successful baryogenesis since $\dot{\theta}$ is proportional to the baryon number density. Similar ratchet models which lead to directed motion have been used in the study of molecular motors in biology. There, the driving force is supplied by chemical reactions, while in our scenario this role is played by the inflaton during the reheating epoch. Keywords: Baryogenesis; Reheating; Inflaton; Ratchet Model; Forced Rotating Pendulum 
Kazuharu Bamba, Neil D. Barrie, Akio Sugamoto, Tatsu Takeuchi, Kimiko   Yamashita
hep-ph