On the waterfall behavior in hybrid inflation

TL;DR

This paper analyzes the waterfall phase in hybrid inflation models, demonstrating that inflation can persist during this phase, leading to a red spectral index compatible with WMAP data.

Contribution

It provides an analytical study of the waterfall dynamics, confirming that inflation can continue during this phase under certain parameters, affecting observable predictions.

Findings

Inflation can last during the waterfall phase in some parameter regions.

The scalar spectral index becomes red during this extended waterfall inflation.

Results align with WMAP observations for certain parameters.

Abstract

We revisit the hybrid inflation model focusing on the dynamics of the waterfall field in an analytical way. It is shown that inflation may last long enough during the waterfall regime for some parameter regions, confirming the claim of Clesse. In this case the scalar spectral index becomes red, and can fall into the best fit range of the WMAP observation.