Neutrinophilic $\mathbf{\Lambda }$CDM Extension for EMPRESS, DESI and Hubble Tension

Abstract

A number of recent cosmological observations have indicated the presence of new physics beyond the $\mathbf{\Lambda }$CDM model. Combining observations from EMPRESS on helium abundance and DESI on baryon acoustic oscillations with Hubble tension, we show that all of them can be explained concurrently with a extension of the $\mathbf{\Lambda }$CDM model with primordial neutrino asymmetry ${\xi }_{\nu }$ and additional contribution to the effective number of neutrinos $\delta N_{\mathrm{eff}}$. Based on the accurate treatments of neutrino decoupling and BBN processes, we present state-of-the-art constraints on neutrino asymmetry for the fixed or varying $N_{\mathrm{eff}}$. Comparing different extensions of the $\mathbf{\Lambda }$CDM model, we show that the neutrinophilic $\mathbf{\Lambda }$CDM extension with ${\xi }_{\nu }=0.056\pm 0.017$ and $\delta N_{\mathrm{eff}}=0.41\pm 0.16$ is preferred by current observations, while the Hubble tension in this model is also alleviated to be $2.2\sigma$.

Comments: 7 pages, 4 figures, and 1 table