Addressing the Hubble and $S_8$ Tensions with a Kinetically Mixed Dark Sector

• DOI: 10.48550/arxiv.2207.13086
• Publication Date: 2022-01-01
• Authors: Stephon Alexander; Heliudson Bernardo; Michael W. Toomey
• Keywords: Dilaton

We present a kinetically mixed dark sector (KMIX) model to address the Hubble and $S_8$ tensions. Inspired from string theory, our includes two fields: an axion, which plays role similar scalar field in early energy models, dilaton. This theory differs other axio-dilaton models aimed at tension that there is necessarily kinetic mixing between fields allows for efficient transfer axion into dilaton has $w\approx1$. As direct consequence of these dynamics, we find does not need resort fine-tuned potential solve naturally accommodates standard potential. Furthermore, will makeup small (fuzzy) fraction $Ω_{\rm cdm}$ once it begins oscillate bottom its suppress growth perturbations on scales sensitive $S_8$. Interestingly, scale be small, $\lesssim \mathcal{O}(10~{\rm meV})^4$, suggesting possibility connection energy. Implementing dynamics background modified Boltzmann code calculate CMB matter power spectra theory. Exploring parameter space model, regions can accommodate $\sim 10\%$ increase $H_0$ Planck inferred value values are consistent with large-scale structure constraints.