Abstract
We consider the astrophysical bounds on a new form of dark matter, the so called Gravity-mediated Dark Matter. In this scenario, dark matter communicates with us through a mediator sector composed of gravitational resonances, namely a new scalar (radion) and a massive spin-two resonance (massive graviton). We consider specific models motivated by natural electroweak symmetry breaking or weak-scale dark matter in the context of models in warped extra-dimensions and their composite duals. The main Dark Matter annihilation mechanism is due to the interactions of KK gravitons to gauge bosons that propagate in bulk. We impose the bounds on monochromatic or continuum photons from Fermi-LAT and HESS. We also explore scenarios in which the Fermi gamma-ray line could be a manifestation of Gravity-mediated Dark Matter.
Highlights
In this paper, we consider a gravity-mediated dark matter, that has been proposed by the authors [47] to relate dark matter mass to the geometric solution of the hierarchy problem in the 5D warped extra dimension with UV and IR branes [48]
In Model B, we show that the Fermi gamma-ray line at about 130 GeV can be obtained from the annihilation of a pair of vector dark matter into a photon pair, which is mediated by the KK graviton without a need of large couplings or resonance
We have investigated a new dark matter model where gravity or composite sector such as a KK graviton in 5D warped spacetime or a spin-2 resonance in the dual conformal theory is responsible for the annihilation of dark matter into the SM particles
Summary
CGX,χ,S, cGV , cGψ , cGH are KK graviton couplings which are determined by the overlap between the wave functions of the KK graviton and fields in extra dimensions, see refs. [59,60,61,62,63,64,65,66,67,68,69] for an example in AdS. X(χ, S), V , H and ψ denote the Dark Matter particle, gauge bosons, Higgs and SM matter fields, respectively. The KK graviton couplings to the electroweak gauge bosons are written schematically: for transverse modes,. For the universal gravity couplings to electroweak gauge bosons, cGW = cGB = cGV , the Zγ coupling vanishes, so there is no DM annihilation into Zγ with graviton mediator.. In warped extra-dimensions, there is a hierarchy of couplings of the graviton to Dark matter, Bulk, Matter and Higgs fields, respectively. In AdS models, the value of cGV is cGV = 2 log 1 − J0(xG). We will present results including the effect of the whole KK-tower This can be done for any metric of the form of eq (2.1) as shown in [77]. See ref. [47] for more details
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