We present a further observational analysis of the ${\mathrm{\Lambda }}_{\mathrm{s}}\mathrm{CDM}$ model proposed in Akarsu et al. [Phys. Rev. D 104, 123512 (2021)]. This model is based on the recent conjecture suggesting the Universe has transitioned from anti–de Sitter vacua to de Sitter vacua (viz., the cosmological constant switches sign from negative to positive), at redshift $z_{†}\sim 2$, inspired by the graduated dark energy model proposed in Akarsu et al. [Phys. Rev. D 101, 063528 (2020)]. ${\mathrm{\Lambda }}_{\mathrm{s}}\mathrm{CDM}$ was previously claimed to simultaneously relax five cosmological discrepancies, namely, the $H_0$, $S_8$, and $M_B$ tensions along with the $\mathrm{Ly}\text{−}\alpha$ and ${\omega }_{\mathrm{b}}$ anomalies, which prevail within the standard $\mathrm{\Lambda }\mathrm{CDM}$ model as well as its canonical/simple extensions. In the present work, we extend the previous analysis by constraining the model using the Pantheon data (with and without the SH0ES $M_B$ prior) and/or the completed BAO data along with the full Planck CMB data. We find that ${\mathrm{\Lambda }}_{\mathrm{s}}\mathrm{CDM}$ exhibits a better fit to the data compared to $\mathrm{\Lambda }\mathrm{CDM}$, and simultaneously relaxes the six discrepancies of $\mathrm{\Lambda }\mathrm{CDM}$, viz., the $H_0$, $M_B$, $S_8$, $\mathrm{Ly}\text{−}\alpha$, $t_0$, and ${\omega }_{\mathrm{b}}$ discrepancies, all of which are discussed in detail. When the $M_B$ prior is included in the analyses, ${\mathrm{\Lambda }}_{\mathrm{s}}\mathrm{CDM}$ performs significantly better in relaxing the $H_0$, $M_B$, and $S_8$ tensions with the constraint $z_{†}\sim 1.8$ even when the $\mathrm{Ly}\text{−}\alpha$ data (which imposed the $z_{†}\sim 2$ constraint in the previous studies) are excluded. In contrast, the presence of the $M_B$ prior causes only negligible improvements for $\mathrm{\Lambda }\mathrm{CDM}$. Thus, the ${\mathrm{\Lambda }}_{\mathrm{s}}\mathrm{CDM}$ model provides remedy to various cosmological tensions simultaneously, only that the galaxy BAO data hinder its success to some extent.

• Received 13 November 2022
• Accepted 9 June 2023

DOI:https://doi.org/10.1103/PhysRevD.108.023513