Quintessence and the Relic Density of Neutralinos

Abstract

The archetypal model for the recently discovered dark energy component of the universe is based on the existence of a scalar field whose dynamical evolution comes down today to a non-vanishing cosmological constant. In the past - before big-bang nucleosynthesis for that matter - that scalar field could have gone through a period of kination during which the universe has expanded at a much higher pace than what is currently postulated in the standard radiation dominated cosmology. I examine here the consequences of such a period of kination on the relic abundance of neutralinos and find that the latter could be much higher - by three orders of magnitude - than what is estimated in the canonical derivation. I shortly discuss the implications of this scenario for the dark matter candidates and their astrophysical signatures. This new version contains a discussion - see section 2 - of the overshooting problem and offers perspectives to reconcile an initial period of violent kination with the existence of a cosmological constant today.