Λ_sCDM cosmology: alleviating major cosmological tensions by predicting standard neutrino properties

In this work, we investigate a two-parameter extension of the Lambda sCDM model, as well as the Lambda CDM model for comparison, by allowing variations in the effective number of neutrino species (N-eff) and their total mass (Sigma m(nu)). Our motivation is twofold: (i) to examine whether the Lambda sCDM framework 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 ( z similar to 2) mirror AdS-to-dS transition feature of the Lambda sCDM model, or in the pre-recombination universe through modifications in the standard values of N-eff and v, or both. Within the extended Lambda sCDM model, referred to as Lambda sCDM+N-eff+Sigma m(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 sCDM extension. However, the weakly model-dependent BAOtr data, along with Planck and Planck+PP&SH0ES, favor an H-0 value of approximately 73km s(-1) Mpc(-1), which aligns perfectly with local measurements. In cases where BAOtr is part of the combined dataset, the mirror AdS-dS transition is very effective in providing enhanced H-0 values, and thus the model requires no significant deviation from the standard value of N-eff = 3.044, remaining consistent with the standard model of particle physics. Both the H-0 and S-8 tensions are effectively addressed, with some compromise in the case of the Planck+BAO dataset. Finally, the upper bounds obtained on total neutrino mass, Sigma m(nu) less than or similar to 0.50 eV, are fully compatible with neutrino oscillation experiments. Our findings provide evidence that late-time physics beyond Lambda CDM, such as Lambda sCDM , without altering the standard description of the pre-recombination universe, can suffice to alleviate the major cosmological tensions, as indicated by our analysis of Lambda sCDM+N-eff+Sigma m(nu).