Gravitational Baryogenesis
  We show that a gravitational interaction between the derivative of the Ricci scalar curvature and the baryon-number current dynamically breaks CPT in an expanding universe and, combined with baryon-number-violating interactions, can drive the universe towards an equilibrium baryon asymmetry that is observationally acceptable. 
Hooman Davoudiasl, Ryuichiro Kitano, Graham D. Kribs, Hitoshi   Murayama, Paul J. Steinhardt (IAS)