Preheating and the non-gaussianity of the curvature perturbation

Understand

The perturbation of a light field might affect preheating and hence generate a contribution to the spectrum and non-gaussianity of the curvature perturbation \zeta.

• The field might appear directly in the preheating model (curvaton-type preheating) or indirectly through its effect on a mass or coupling (modulated preheating).
• We give general expressions for \zeta based on the \delta N formula, and apply them to the cases of quadratic and quartic chaotic inflation.
• For the quadratic case, curvaton-type preheating is ineffective in contributing to \zeta, but modulated preheating can be effective.