Speaker
Description
In this talk, we will first give a brief introduction to the $\Lambda_{\rm s}$CDM model, which explores the recent conjecture suggesting a rapid transition of the universe from anti-de Sitter vacua to de Sitter vacua, viz., the cosmological constant switches sign from negative to positive at redshift ${z_\dagger\sim 1.7}$, inspired by the graduated dark energy (gDE). And then, we will present the results of its comprehensive observational analysis showing that, predicting $z_\dagger\approx1.7$, $\Lambda_{\rm s}$CDM simultaneously addresses the major cosmological tensions of the standard $\Lambda$CDM model, viz., the $H_0$, $M_B$, and $S_8$ tensions, along with some other less significant tensions such as the BAO Ly-$\alpha$ discrepancy. We will conclude with a theoretical discussion on the possible physical mechanisms from which this scenario may be realized and their implications for our current understanding of the universe.
