Coannihilation without chemical equilibrium

Chemical equilibrium is a commonly made assumption in the freeze-out calculation of coannihilating dark matter. We explore the possible failure of this assumption and find a new conversion-driven freeze-out mechanism. Considering a representative simplified model inspired by supersymmetry with a neu...

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Bibliographic Details
Published in:Physical review. D 2017-11, Vol.96 (10), Article 103521
Main Authors: Garny, Mathias, Heisig, Jan, Lülf, Benedikt, Vogl, Stefan
Format: Article
Language:English
Subjects:
Conversion
Couplings
Dark matter
Density
Equilibrium
Heating
Initial conditions
Large Hadron Collider
Organic chemistry
Parameters
Supersymmetry
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Summary:Chemical equilibrium is a commonly made assumption in the freeze-out calculation of coannihilating dark matter. We explore the possible failure of this assumption and find a new conversion-driven freeze-out mechanism. Considering a representative simplified model inspired by supersymmetry with a neutralinolike and sbottomlike particle we find regions in parameter space with very small couplings accommodating the measured relic density. In this region freeze-out takes place out of chemical equilibrium and dark matter self-annihilation is thoroughly inefficient. The relic density is governed primarily by the size of the conversion terms in the Boltzmann equations. Due to the small dark matter coupling the parameter region is immune to direct detection but predicts an interesting signature of disappearing tracks or displaced vertices at the LHC. Unlike freeze-in or superWIMP scenarios, conversion-driven freeze-out is not sensitive to the initial conditions at the end of reheating.
ISSN:2470-0010
2470-0029
DOI:10.1103/PhysRevD.96.103521