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 $\delta N_{\rm eff}$. 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 $N_{\rm eff}$. 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 $\delta N_{\rm eff} = 0.41 \pm 0.16$ is preferred by current observations, while the Hubble tension in this model is also alleviated to be $2.2 \sigma$.