Tracking Quintessence and Cold Dark Matter Candidates - High Energy Physics - PhenomenologyReport as inadecuate

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Abstract: We study the generation of a kination-dominated phase in the context of aquintessential model with an inverse-power-law potential and a Hubble-inducedmass term for the quintessence field. The presence of kination is associatedwith an oscillating evolution of the quintessence field and the barotropicindex. We find that, in sizeable regions of the parameter space, a trackerscaling solution can be reached sufficiently early to alleviate the coincidenceproblem. Other observational constraints originating from nucleosynthesis, theinflationary scale, the present acceleration of the universe and thedark-energy-density parameter can be also met. The impact of this modifiedkination-dominated phase on the thermal abundance of cold dark mattercandidates is investigated too. We find that: i the enhancement of the relicabundance of the WIMPs with respect to the standard paradigm, crucially dependson the hierarchy between the freeze-out temperature and the temperature atwhich the extrema in the evolution of the quintessence field are encountered,and ii the relic abundance of e-WIMPs takes its present value close to thetemperature at which the earliest extremum of the evolution of the quintessencefield occurs and, as a consequence, both gravitinos and axinos arise as naturalcold dark matter candidates. In the case of unstable gravitinos, the gravitinoconstraint can be satisfied for values of the initial temperature well abovethose required in the standard cosmology.

Author: S. Lola, C. Pallis, E. Tzelati


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