Thermal Effects and Sudden Decay Approximation in the Curvaton Scenario

Understand

We study the impact of a temperature-dependent curvaton decay rate on the primordial curvature perturbation generated in the curvaton scenario.

• Using the familiar sudden decay approximation, we obtain an analytical expression for the curvature perturbation after the decay of the curvaton.
• We then investigate numerically the evolution of the background and of the perturbations during the decay.
• We first show that the instantaneous transfer coefficient, related to the curvaton energy fraction at the decay, can be extended into a more general parameter, which depends on the net transfer of the curvaton energy into radiation energy or, equivalently, on the total entropy ratio after the complete curvaton decay.