大望远镜氦丰度测量对宇宙学参数的影响
Big Bang For Your Helium Buck
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- University of Washington（华盛顿大学）
- Perimeter Institute for Theoretical Physics（理论物理前沿研究所）
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中文总结 AI 辅助
利用LBT对原始氦丰度的测量，我们展示了不依赖BBN的CMB宇宙学约束的稳健性，并应用于新物理场景，排除了多数模型，同时为中子寿命异常提供了独立检验。
中文摘要 AI 辅助
我们研究了大双筒望远镜（LBT）最近对原始氦丰度测量的结果对宇宙微波背景（CMB）宇宙学推断的影响。我们表明，LBT的测量确立了宇宙学参数对大爆炸核合成（BBN）理论假设的稳健性：其对氦丰度的经验校准使得对宇宙学和暴胀的约束不依赖于BBN，但精度与强制执行标准BBN预测的约束相当。未来的CMB巡天在辐射密度自由时，至多需要对LBT精度进行边际改进，以最大化其不依赖BBN的约束能力（在我们考虑的所有情况下，改进不超过两倍）。然后，我们将LBT测量应用于若干涉及BBN和CMB中新物理的场景。首先，我们约束非标准辐射扇区（相互作用和自由流），并搜索核合成与重组之间辐射丰度的演化。接着，我们测试缓解哈勃常数张力和CMB与重子声学振荡数据之间张力的模型，包括自相互作用轻 relics 和变化的基本常数；LBT通过其对BBN的影响排除了我们考虑的大多数模型，但并非全部。最后，我们利用LBT测量作为对中子寿命异常的间接但独立的检验，推断出的值与“瓶”实验一致，比“束”实验低2.4σ。
英文摘要
We study the implications of a recent measurement of the primordial helium fraction from the Large Binocular Telescope for cosmological inference from the cosmic microwave background. We show that LBT establishes the robustness of cosmological parameters to theoretical assumptions about big bang nucleosynthesis: its empirical calibration of the helium fraction enables constraints on cosmology and inflation that are agnostic to BBN but as precise as those that instead enforce standard BBN predictions. Future CMB surveys require at most a marginal improvement in precision over LBT to maximize their BBN-agnostic constraining power when the radiation density is free (and no more than a factor of two improvement across all cases we consider). We then apply the LBT measurement to a number of scenarios that feature new physics in BBN and the CMB. First, we constrain nonstandard radiation sectors (interacting and free-streaming) and search for evolution of the radiation abundance between nucleosynthesis and recombination. We then test models that alleviate the Hubble tension and the tension between CMB and baryon acoustic oscillation data, including self-interacting light relics and varying fundamental constants; LBT precludes most but not all of the models we consider via their effect on BBN. Finally, we use the LBT measurement as an indirect but independent test of the neutron lifetime anomaly, inferring values that are consistent with "bottle" experiments and $2.4 σ$ below "beam" experiments.
