Curvaton model completed

In an inflationary cosmology, the observed primoridal density perturbation could come from the quantum fluctuations of another light 'curvaton' field, rather than the inflaton. In this case, it is essential that the curvaton decays, converting its perturbation to an adiabatic perturbation. For the first time, we consistently account for this decay in the simplest curvaton model V(\sigma) = (m^2\sigma^2)/2 and point out that it gives rise to an important logarithmic correction to the potential. Moreover, the potential will also receive a correction from the thermal bath. As a consequence, the dynamics of the curvaton are substantially altered compared to the original model in the majority of the parameter space. It will therefore be necessary to re-calculate all the predictions of the original model.