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- Cornell, Jonathan M., et al.
(författare)
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Dark matter in minimal universal extra dimensions with a stable vacuum and the right Higgs boson
- 2014
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Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 89:5, s. 056005-
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Tidskriftsartikel (refereegranskat)abstract
- The recent discovery of a Higgs boson with mass of about 125 GeV, along with its striking similarity to the prediction from the standard model, informs and constrains many models of new physics. The Higgs mass exhausts one out of three input parameters of the minimal, five-dimensional version of universal extra dimension models, the other two parameters being the Kaluza-Klein (KK) scale and the cutoff scale of the theory. The presence of KK fermions with large coupling to the Higgs implies a short-lived electroweak vacuum, unless the cutoff scale is at most a few times higher than the KK mass scale, providing an additional tight constraint to the theory parameter space. Here, we focus on the lightest KK particle as a dark matter candidate, and investigate the regions of parameter space where such particle has a thermal relic density in accord with the cosmological dark matter density. We find the paradoxical result that, for low enough cutoff scales consistent with vacuum stability, larger than previously thought KK mass scales become preferred to explain the dark matter abundance in the Universe. We explain this phenomenon by pinpointing the additional particles which, at such low cutoffs, become close enough in mass to the dark matter candidate to coannihilate with it. We make predictions for both collider and direct dark matter searches that might soon close in on all viable theory parameter space.
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| 2. |
- Cornell, Jonathan M., et al.
(författare)
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Kinetic decoupling and small-scale structure in effective theories of dark matter
- 2013
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Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 88:1, s. 015027-
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Tidskriftsartikel (refereegranskat)abstract
- The size of the smallest dark matter collapsed structures, or protohalos, is set by the temperature at which dark matter particles fall out of kinetic equilibrium. The process of kinetic decoupling involves elastic scattering of dark matter off of Standard Model particles in the early universe, and the relevant cross section is thus closely related to the cross section for dark matter scattering off of nuclei (direct detection) but also, via crossing symmetries, for dark matter pair production at colliders and for pair annihilation. In this study, we employ an effective-field-theoretic approach to calculate constraints on the kinetic decoupling temperature, and thus on the size of the smallest protohalos, from a variety of direct, indirect and collider probes of particle dark matter.
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