The simplest curvaton model
  We analyze the simplest possible realization of the curvaton scenario, where a nearly scale-invariant spectrum of adiabatic perturbations is generated by conversion of an isocurvature perturbation generated during inflation, rather than the usual inflationary mechanism. We explicitly evaluate all the constraints on the model, under both the assumptions of prompt and delayed reheating, and outline the viable parameter space. 
N Bartolo and Andrew R Liddle