Curvaton Decay by Resonant Production of the Standard Model Higgs
  We investigate in detail a model where the curvaton is coupled to the
Standard Model higgs. Parametric resonance might be expected to cause a fast
decay of the curvaton, so that it would not have time to build up the curvature
perturbation. However, we show that this is not the case, and that the resonant
decay of the curvaton may be delayed even down to electroweak symmetry
breaking. This delay is due to the coupling of the higgs to the thermal
background, which is formed by the Standard Model degrees of freedom created
from the inflaton decay. We establish the occurrence of the delay by
considering the curvaton evolution and the structure of the higgs resonances.
We then provide analytical expressions for the delay time, and for the
subsequent resonant production of the higgs, which ultimately leads to the
curvaton effective decay width. Contrary to expectations, it is possible to
obtain the observed curvature perturbation for values of the curvaton-higgs
coupling as large as 0.1. Our calculations also apply in the general case of
curvaton decay into any non Standard Model species coupled to the thermal
background.
