Hadronic axion model in gauge-mediated supersymmetry breaking and the cosmology of the saxion

Abstract

Recently we have proposed a simple hadronic axion model within gaugemediated supersymmetry breaking. In this paper we discuss various cosmological consequences of the model in great detail. A particular attention is paid to a saxion, a scalar partner of an axion, which is produced as a coherent oscillation in the early universe. We show that our model is cosmologically viable, if the reheating temperature of inflation is sufficiently low. We also discuss the late decay of the saxion which gives a preferable power spectrum of the density fluctuation in the standard cold dark matter model when compared with the observation.

Axions: Theory and Cosmological Role

“…In the gauge-mediated SUSY breaking (GMSB) model, the dominant contribution to the soft SUSY breaking mass often comes from the GMSB effect, while small but non-negligible gravity-mediation effect generally exists. In particular, for a gauge-singlet scalar such as the PQ scalar, the effect of GMSB on its potential is rather non-trivial because it arises at higher loop level [99,100,101].…”

Cosmological implications of supersymmetric axion models

“…In SUSY axion models, both the scalar partner of the axion, saxion, and the fermionic superpartner of the axion, axino, have significant effects on cosmology. But there have not been many studies which treat both of them in spite of their importance [6,7,8,9]. Moreover, these earlier works were based on specific models and only the restricted parameter regions were investigated.…”

Increasing the Effective Number of Neutrinos with Decaying Particles

“…The saxion abundance depends on the thermal history of the universe, e.g., whether the reheating completes before or after the saxion starts to oscillate [36]. First let us assume that the saxion starts to oscillate after the reheating.…”