Kinetic Mixing, Dark Photons and Extra Dimensions II: Fermionic Dark Matter

Abstract

Extra dimensions can be very useful tools when constructing new physics models. Previously, we began investigating toy models for the 5-D analog of the kinetic mixing/vector portal scenario where the interactions of bulk dark matter with the brane-localized fields of the Standard Model are mediated by a massive $U(1{)}_D$ dark photon also living in the bulk. In that setup, where the dark matter was taken to be a complex scalar, a number of nice features were obtained such as $U(1{)}_D$ breaking by boundary conditions without the introduction of a dark Higgs field, the absence of potentially troublesome SM Higgs-dark singlet mixing, also by boundary conditions, the natural similarity of the dark matter and dark photon masses and the decoupling of the heavy gauge Kaluza-Klein states from the Standard Model. In the present paper we extend this approach by examining the more complex cases of Dirac and Majorana fermionic dark matter. In particular, we discuss a new mechanism that can occur in 5-D (but not in 4-D) that allows for light Dirac dark matter in the $\sim 100$ MeV mass range, even though it has an $s$-wave annihilation into Standard Model fields, by avoiding the strong constraints that arise from both the CMB and 21 cm data. This mechanism makes use of the presence of the Kaluza-Klein excitations of the dark photon to extremize the increase in the annihilation cross section usually obtained via resonant enhancement. In the Majorana dark matter case, we explore the possibility of a direct $s$-channel dark matter pair-annihilation process producing the observed relic density, due to the general presence of parity-violating dark matter interactions, without employing the usual co-annihilation mechanism which is naturally suppressed in this 5-D setup.

22 pages, 7 Figs; discussions and refs. added, typos fixed; title changed to match earlier work

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Cited by in corpus (22)

• The Warped Dark Sector
• Kinetic Mixing and Portal Matter Phenomenology
• Dark Matter and Leptogenesis from Gravitational Production
• Polynomial Inflation and Dark Matter
• Gravity-mediated Scalar Dark Matter in Warped Extra-Dimensions
• Kaluza-Klein FIMP Dark Matter in Warped Extra-Dimensions
• Non-minimally Coupled Vector Boson Dark Matter
• Gravity-mediated Dark Matter in Clockwork/Linear Dilaton Extra-Dimensions
• FIMP Dark Matter in Clockwork/Linear Dilaton Extra-Dimensions
• Dark Initial State Radiation and the Kinetic Mixing Portal
• Thick Branes in Extra Dimensions and Suppressed Dark Couplings
• An Extra-Dimensional Model of Dark Matter
• Spin-dependence of Gravity-mediated Dark Matter in Warped Extra-Dimensions
• Strong Constraints on Dark Photon and Scalar Dark Matter Decay from INTEGRAL and AMS-02 data
• Compactified extra dimension and entanglement island as clues to quantum gravity
• Fat brane, dark matter and localized kinetic terms in six dimensions
• Fat brane and seesaw mechanism in extra dimensions
• The Bactrian Effect: Multiple Resonances and Light Dirac Dark Matter
• Prospects of five-dimensional $L_{\mu }-L_{\tau }$ gauge interactions in the light of elastic neutrino-electron scatterings: The scope of the DUNE near detector
• Gravitational SIMPs
• Adagio for Thermal Relics
• Higgs Production in Association with a Dark-Z at Future Electron Positron Colliders