Solving the Hubble tension without spoiling big bang nucleosynthesis

  title={Solving the Hubble tension without spoiling big bang nucleosynthesis},
  author={Guo-Yuan Huang and Werner Rodejohann},
The Hubble parameter inferred from cosmic microwave background observations is consistently lower than that from local measurements, which could hint towards new physics. Solutions to the Hubble tension typically require a sizable amount of extra radiation ∆Neff during recombination. However, the amount of ∆Neff in the early Universe is unavoidably constrained by Big Bang Nucleosynthesis (BBN), which causes problems for such solutions. We present a possibility to evade this problem by… 

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