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

The well-known tensions on the cosmological parameters H0 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 H0 and sigma 8 tensions disappear. In the joint analyses 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 H0 and sigma 8 tensions simultaneously.