We investigate how sterile neutrinos with a range of masses influence cosmology in MeV-scale reheating temperature scenarios. By computing the production of sterile neutrinos through the combination of mixing and scattering in the early Universe, we find that light sterile neutrinos, with masses and mixings as inferred from short-baseline neutrino oscillation experiments, are consistent with big-bang nucleosynthesis (BBN) and cosmic microwave background (CMB) radiation for the reheating temperature of ${\cal O}(1)$ MeV if the parent particle responsible for reheating decays into electromagnetic components (radiative decay). In contrast, if the parent particle mainly decays into hadrons (hadronic decay), the bound from BBN becomes more stringent. In this case, the existence of the light sterile neutrinos can be cosmologically excluded, depending on the mass and the hadronic branching ratio of the parent particle.

中文翻译：

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轻型无菌中微子的 MeV 级再加热温度和宇宙学产生

我们研究了具有一系列质量的无菌中微子如何在 MeV 级再加热温度情景中影响宇宙学。通过计算早期宇宙中混合和散射相结合产生的惰性中微子，我们发现从短基线中微子振荡实验推断出的具有质量和混合的轻惰性中微子与大爆炸核合成（BBN）一致如果负责再加热的母粒子衰变成电磁成分（辐射衰变），则再加热温度为 ${\cal O}(1)$ MeV 的宇宙微波背景 (CMB) 辐射。相比之下，如果母粒子主要衰变成强子（强子衰变），则来自 BBN 的束缚变得更加严格。在这种情况下，可以从宇宙学上排除轻惰性中微子的存在，