Baryon-dark matter coincidence in Randall-Sundrum Model

TL;DR

This work analyzes DM generation and the baryon asymmetry in a Randall–Sundrum setup where the SM and DM reside on the IR brane and communicate through radion and KK-graviton portals. DM is produced by UV freeze-in via radius and graviton exchange, with the yield controlled by the reheating temperature $T_{rh}$ and the radion scale $\Lambda_r$, allowing the observed relic density to be achieved across wide $(m_{DM}, T_{rh}, \, \\Lambda_r)$ ranges while addressing the hierarchy problem. The same RS framework supports TeV-scale leptogenesis through resonant CP-violating decays of TeV-scale right-handed neutrinos produced from the thermal bath, linking DM and BAU generation; sphaleron processes then translate the lepton asymmetry into a baryon asymmetry. Collider constraints from LHC graviton searches, together with constraints from reheating and $\\Delta N_{ m eff}$, tightly bound the viable parameter space, emphasizing complementary information between collider data and early-universe cosmology. Overall, the paper presents a coherent scenario in which the DM abundance, BAU, and the hierarchy problem are simultaneously addressed within warped extra dimensions, with testable implications for future cosmological and collider experiments.

Abstract

Within the framework of the extra-dimensional Randall-Sundrum set-up, we investigate the freeze-in production of Standard Model (SM) gauge-singlet scalar, fermionic, and massive vector dark matter (DM). Assuming that both the DM and SM fields reside on the IR brane and interact solely through the graviton and radion, we demonstrate that the observed DM relic abundance measured by Planck can be achieved across a wide range of reheating temperatures, all while naturally addressing the hierarchy problem, satisfying constraints from collider, early Universe cosmology including $Δ{N}_{\rm eff}$. We further show that the same set-up can accommodate TeV-scale leptogenesis capable of generating the observed baryon asymmetry of the Universe. Remarkably, we find that current graviton searches at the Large Hadron Collider (LHC) already impose strong constraints on the reheating temperature in this scenario.

Figures (8)

• Figure 1: Schematic diagram showing our scenario. Only graviton is capable of accessing the bulk. This figure is generated using online math editor mathcha.io.
• Figure 2: Freeze-in production of DM from scattering of the bath particles via radion portal (left) or graviton portal (right). The DM can be a spin-0, spin-1/2, or spin-1 field. Similar processes also produce RHNs that participate in baryogenesis via leptogenesis.
• Figure 3: Left: DM production cross-section as function of $s$, taking into account both radion and graviton exchange. Right: Reaction density as a function of temperature $T$. We fix $\Lambda_r=100$ TeV, $m_{\rm DM}=1$ GeV, $m_r=1$ TeV, $kr_c=11$ (corresponding graviton mass can be derived from Tab. \ref{['tab:mn']}) and consider scalar DM. The shaded regions violate the effective theory condition.
• Figure 4: Contours of right relic abundance for a DM of mass $m_{\rm DM}\simeq2300$ GeV, with corresponding $kr_c=11$, shown in the top panel, considering different DM spins. The red solid, green dashed, and blue dot-dashed contours correspond to spin-0, spin-1, and spin-1/2 DM, respectively. The bottom panel shows the same, but for a DM of mass 1 MeV. In all cases, we have fixed $m_r=1$ TeV and follow Tab. \ref{['tab:mn']} for the graviton mass. We show regions excluded from DM thermalization condition (in lighter gray), BBN bound on the reheating temperature (in darker gray), instantaneous reheating condition (in pink, in the top panel), and violation of effective theory (in cyan & in darker red). Within the green shaded region, the hierarchy problem can be addressed.
• Figure 5: Contours of right DM abundance for different DM spins, considering $m_r=1$ TeV, $\Lambda_r=10$ TeV in the left panel and $\Lambda_r=10^5$ TeV in the right panel. The red solid, green dashed, and blue dot-dashed contours correspond to spin-0, spin-1, and spin-1/2 DM, respectively. Different shaded regions are excluded from the DM thermalization condition (in lighter gray), the BBN bound on the reheating temperature (in darker gray), and the instantaneous reheating condition (in lighter red). In the right panel inset, we have zoomed into the relic density contours corresponding to different spins to show them more clearly.