We consider the cosmological effects of sterile neutrinos with the masses of $150- 450$ MeV. The decay of sterile neutrinos changes the thermal history of the Universe and affects the energy density of radiation at the recombination and the big bang nucleosynthesis (BBN) results. We derive severe constraints on the parameters of sterile neutrinos from the primordial abundances of helium-4 and deuterium. We also find that in a particular model the constraints can be considerably relaxed by assuming a large lepton asymmetry in the active neutrinos. In this case, the consistent parameters result in $N_{\mathrm{eff}} \simeq 3.2- 3.4$ and can alleviate the Hubble tension.

中文翻译：

---

宇宙的惰性中微子和轻子不对称性的大爆炸核合成约束

我们考虑质量为 $150- 450 $ MeV 的无菌中微子的宇宙学效应。惰性中微子的衰变改变了宇宙的热历史，并影响了复合时辐射的能量密度和大爆炸核合成 (BBN) 结果。我们从氦 4 和氘的原始丰度中得出对惰性中微子参数的严格限制。我们还发现，在特定模型中，假设活动中微子中存在较大的轻子不对称性，可以大大放松约束。在这种情况下，一致的参数导致 $N_{\mathrm{eff}} \simeq 3.2- 3.4$ 并且可以减轻哈勃张力。