We propose a mechanism by which the inflaton can generate baryogenesis, by
taking the inflaton to be a complex scalar field with a weakly broken global
symmetry and present a new version of the Affleck-Dine mechanism. The smallness
of the breaking is motivated both by technical naturalness and a requirement
for inflation. We study inflation driven by a quadratic potential for
simplicity and discuss generalizations to other potentials. We compute the
inflationary dynamics and find that a conserved particle number is obtained
towards the end of inflation. We then explain in detail the later decay to
baryons. We present two promising embeddings in particle physics: (i) using
high dimension operators for a gauge singlet; we find this leads to the
observed asymmetry for decay controlled by the ~ grand unified theory scale and
this is precisely the regime where the effective field theory applies. (ii)
using a colored inflaton, which requires small couplings. We also point out two
observational consequences: a possible large scale dipole in the baryon
density, and a striking prediction of isocurvature fluctuations whose amplitude
is found to be just below current limits and potentially detectable in future
data.Comment: 18 pages (double column format), 4 figures, v2: Some clarifications,
more references, updated to resemble version published in PR
