Impact of big bang nucleosynthesis on the H 0 tension

Abstract

Abstract We investigate the impact of big bang nucleosynthesis (BBN) on the Hubble tension, focusing on how the treatment of the reaction rate and observational data affect the evaluation of the tension. We show that the significance of the tension is increased to 4.41σ from 3.61σ and to 5.22σ from 4.58σ in axionlike early dark energy model with n = 2 and n = ∞, respectively, depending on the treatment of the reaction rate and observational data. This indicates that how we include the BBN data in the analysis can give a significant impact on the Hubble tension, and we need to carefully consider the assumptions of the analysis to evaluate the significance of the tension when the BBN data is used.