Cosmological aspects of inflation in a supersymmetric axion model

TL;DR

This paper demonstrates that hybrid inflation naturally occurs within a supersymmetric axion framework, resolving cosmological issues and allowing axions to be a dominant dark matter component.

Contribution

It introduces a model where hybrid inflation is realized in a supersymmetric axion context, addressing cosmological problems and axion dark matter.

Findings

Saxion oscillates with large amplitude after inflation.

Decay of saxion produces large entropy, diluting axions.

Axions can be the dominant dark matter component.

Abstract

We show that the hybrid inflation is naturally realized in the framework of a supersymmetric axion model, which is consistent with the WMAP observation if the Peccei-Quinn symmetry breaking scale is around 10^{15}GeV. By solving the post inflationary scalar dynamics, it is found that the scalar partner of the axion, saxion, oscillates with large amplitude and its decay produces a huge entropy and dilutes the axion. As a result, the axion coherent oscillation can be the dominant component of the dark matter in the Universe. Cosmological gravitino and axino problems are solved.