# Dark sector interaction: a remedy of the tensions between CMB and LSS data

## TL;DR

This paper explores a minimal extension to the $$CDM model by introducing a dark sector interaction, which alleviates the tensions in $H_0$ and $$8$ measurements from Planck-CMB and LSS data, supported by observational evidence.

## Contribution

It demonstrates that allowing a coupling between dark energy and dark matter can resolve key cosmological tensions and is statistically supported by current observational data.

## Key findings

- Dark sector coupling removes $H_0$ and $$8$ tensions at 68",
- Non-zero dark sector interaction supported at 99",
- Statistical evidence favors dark sector interaction.

## Abstract

The well-known tensions on the cosmological parameters $H_0$ and $\sigma_8$ within the $\Lambda$CDM cosmology shown by the Planck-CMB and LSS data are possibly due to the systematics in the data or our ignorance of some new physics beyond the $\Lambda$CDM model. In this letter, we focus on the second possibility, and investigate a minimal extension of the $\Lambda$CDM model by allowing a coupling between its dark sector components (dark energy and dark matter). We analyze this scenario with Planck-CMB, KiDS and HST data, and find that the $H_0$ and $\sigma_8$ tensions disappear at 68\% CL. In the joint analyzes with Planck, HST and KiDS data, we find non-zero coupling in the dark sector up to 99\% CL. Thus, we find a strong statistical support from the observational data for an interaction in the dark sector of the Universe while solving the $H_0$ and $\sigma_8$ tensions simultaneously.