Local Universe observations find a value of the Hubble constant H ₀ that is larger than the value inferred from the Cosmic Microwave Background and other early Universe measurements, assuming known physics and the ΛCDM cosmological model. We show that additional radiation in active neutrinos produced just before Big Bang Nucleosynthesis by an unstable sterile neutrino with mass m_s = O(10) MeV can alleviate this discrepancy. The necessary masses and couplings of the sterile neutrino, assuming it mixes primarily with ν_τ and/or ν_μ neutrinos, are within reach of Super-Kamiokande as well as upcoming laboratory experiments such as NA62 and DUNE.

假设已知物理学和 ΛCDM 宇宙学模型，本地宇宙观测发现哈勃常数H ₀的值大于从宇宙微波背景和其他早期宇宙测量推断的值。我们表明，在大爆炸核合成之前由质量为m _s = O(10) MeV的不稳定无菌中微子产生的活性中微子中的额外辐射可以缓解这种差异。惰性中微子的必要质量和耦合（假设它主要与 ν _τ和/或 ν _μ中微子混合）在超级神冈以及即将进行的实验室实验（如 NA62 和 DUNE）的范围内。