Axinos as Dark Matter in the Universe

TL;DR

This paper investigates axinos, the fermionic partners of axions, as potential dark matter candidates, calculating their relic density and comparing it with cosmological observations to assess their viability.

Contribution

It provides a detailed calculation of thermally produced axino relic density and explores conditions under which axinos could account for dark matter.

Findings

Thermally produced axinos can dominate cold dark matter.

Axino mass of 100 keV and reheating temperature of 10^6 GeV are compatible with observations.

Axinos could be the primary component of dark matter in the universe.

Abstract

The axino is the fermionic superpartner of the axion. Assuming the axino is the lightest supersymmetric particle and stable due to R-parity conservation, we compute the relic axino density from thermal reactions in the early Universe. From the comparison with the WMAP results, we find that thermally produced axinos could provide the dominant part of cold dark matter, for example, for an axino mass of 100 keV and a reheating temperature of 10^6 GeV.