  The spectrum of energy density fluctuations, baryon asymmetry, and coherent
large-scale magnetic fields are the three observables that provide crucial
information on physics at very high energies. Inflation can only provide a
mechanism to explain the density perturbations, and the origin of primordial
magnetic fields and baryon asymmetry require physics beyond the standard models
of cosmology and particle physics. In this work, we show that the mechanism
that leads to primordial helical fields also leads to baryogenesis at the
beginning of the radiation-dominated epoch. The model we consider here consists
of mass dimension 6 operators that include Riemann coupling between gravity and
electromagnetic field without extending the Standard Model of particle physics.
We explicitly show that the generation of primordial helical magnetic fields
leads to baryogenesis. We further show that the model predicts the observed
amount of baryon asymmetry of the Universe for a range of reheating
temperatures consistent with the observations.
