$\Lambda_{\rm s}$CDM cosmology: Alleviating major cosmological tensions by predicting standard neutrino properties

Understand

We investigate a two-parameter extension of the $\Lambda_{\rm s}$CDM model by allowing variations in the effective number of neutrino species $N_{\rm eff}$ and their total mass $\sum m_\nu$.

• Our motivation is twofold: (i) to examine whether $\Lambda_{\rm s}$CDM retains its success in fitting the data and addressing major cosmological tensions, without suggesting a need for a deviation from the standard model of particle physics, and (ii) to determine whether the data indicate new physics that could potentially address cosmological tensions, either in the post-recombination universe through the late-time mirror AdS-dS transition, or in the pre-recombination universe through modifications in the standard values of $N_{\rm eff}$ and $\sum m_\nu$, or both.
• Within the extended $\Lambda_{\rm s}$CDM model, referred to as $\Lambda_{\rm s}$CDM+$N_{\rm eff}$+$\sum m_{\rm \nu}$, we find no significant tension when considering the Planck-alone analysis.
• We observe that incorporating BAO data limits the further success of the $\Lambda_{\rm s}$CDM extension.