Neutrino puzzle: Anomalies, interactions, and cosmological tensions
Neutrino puzzle: Anomalies, interactions, and cosmological tensions
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DOI：
10.1103/physrevd.101.123505
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发表时间：
2019-02
影响因子：
5
通讯作者：
C. Kreisch;F. Cyr-Racine;O. Dor'e
中科院分区：
文献类型：
--
作者：
C. Kreisch;F. Cyr-Racine;O. Dor'e
中微子领域的新物理学可能需要解决不同中微子振荡实验之间的异常现象。有趣的是，它还为 H0 和 σ8 的宇宙学测量差异提供了可能的解决方案。我们在这里表明，延迟中微子自由流的开始直到接近物质辐射平等时代可以自然地容纳较大的哈勃常数 H0=72.3±1.4 km s−1 Mpc−1 和较低的物质涨落值 σ8=0.786±0.020，同时不会降低对宇宙微波背景（CMB）阻尼尾的拟合。我们通过在中微子质量不为零的情况下引入中微子自相互作用来实现这一目标。在没有明确纳入额外中微子种类的情况下，这种强相互作用的中微子宇宙学更倾向于 Neff=4.02±0.29，这对粒子模型构建和中微子振荡异常具有有趣的影响。我们表明，宇宙微波背景上中微子自由流相移的缺失可以通过改变几个宇宙学参数的值来补偿，因此为文献中的检测提供了一个重要的警告。由于它们对早期引力势演化的影响，自相互作用中微子及其随后的解耦在物质功率谱上留下了丰富的结构。特别是，我们指出在中微子自由流开始时进入视界的尺度上存在一种新颖的局部特征。虽然相互作用的中微子宇宙学为当前的宇宙学数据提供了更好的全局拟合，但我们发现，与标准宇宙学场景相比，传统的贝叶斯分析对模型不利，因为数据所支持的中微子相互作用强度的范围相对较窄。我们提出的模型说明了理想的宇宙学影响，以同时解决哈勃常数和物质聚集张力，而不是提出可行的粒子模型。我们的分析表明，有可能找到完全不同的宇宙学模型，但这些模型仍然能够很好地拟合数据，从而为彻底探索替代宇宙学场景提供动力。
New physics in the neutrino sector might be necessary to address anomalies between different neutrino oscillation experiments. Intriguingly, it also offers a possible solution to the discrepant cosmological measurements of H0 and σ8. We show here that delaying the onset of neutrino free streaming until close to the epoch of matter-radiation equality can naturally accommodate a larger value for the Hubble constant H0=72.3±1.4 km s−1 Mpc−1 and a lower value of the matter fluctuations σ8=0.786±0.020, while not degrading the fit to the cosmic microwave background (CMB) damping tail. We achieve this by introducing neutrino self-interactions in the presence of a nonvanishing sum of neutrino masses. Without explicitly incorporating additional neutrino species, this strongly interacting neutrino cosmology prefers Neff=4.02±0.29, which has interesting implications for particle model building and neutrino oscillation anomalies. We show that the absence of the neutrino free-streaming phase shift on the CMB can be compensated for by shifting the values of several cosmological parameters, hence providing an important caveat to the detections made in the literature. Due to their impact on the evolution of the gravitational potential at early times, self-interacting neutrinos and their subsequent decoupling leave a rich structure on the matter power spectrum. In particular, we point out the existence of a novel localized feature appearing on scales entering the horizon at the onset of neutrino free streaming. While the interacting neutrino cosmology provides a better global fit to current cosmological data, we find that traditional Bayesian analyses penalize the model as compared to the standard cosmological scenario due to the relatively narrow range of neutrino interaction strengths that is favored by the data. The model we present illustrates desirable cosmological impacts to simultaneously resolve the Hubble constant and matter clustering tensions rather than proposing a viable particle model. Our analysis shows that it is possible to find radically different cosmological models that nonetheless provide excellent fits to the data, hence providing an impetus to thoroughly explore alternate cosmological scenarios.