Issues concerning the waterfall of hybrid inflation

Understand

We discuss the waterfall that ends hybrid inflation.

• Making some simplifying assumptions, that may be satisfied by GUT inflation models, two issues are addressed.
• First, the procedure of keeping the quantum fluctuation of the waterfall field only in the regime where it can be regarded as classical.
• Second, the contribution to the primordial curvature perturbation that is generated during the waterfall.