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arXiv 2409.08280hep-ph
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原初轻子不对称性:中微子输运、谱畸变与宇宙学约束

Primordial lepton asymmetries: neutrino transport, spectral distortions and cosmological constraints

Yuan-Zhen Li, Jiang-Hao Yu

AI总结:

本研究通过精确求解中微子退耦的量子动力学方程,结合多类宇宙学观测数据,对原初中微子不对称性开展综合分析并给出更严格的约束,为相关紫外模型提供限制。

摘要:

原初中微子不对称性在宇宙演化历史上留下了深刻印记,可通过大爆炸核合成(BBN)、宇宙微波背景(CMB)和大尺度结构(LSS)等宇宙学观测进行约束。本文基于闭合时间路径形式下求解完整的(反)中微子量子动力学方程所得到的中微子退耦精确处理,对原初中微子不对称性的影响与约束开展了综合分析。假设所有中微子味具有相同的原初不对称性$ξ_ν$,我们计算了有效中微子数$N_{\rm eff}$和(反)中微子谱畸变,发现非瞬时退耦修正为$δN_{\rm eff} = 0.0440 + 0.0102 \\, ξ_ν^2$。随后我们对包含(反)中微子谱畸变的轻元素丰度进行了前沿水平的计算,结果显示EMPRESS数据给出正不对称性约束为$0.032 \leq ξ_ν \leq 0.052$。本文详细研究了中微子不对称性对CMB和LSS的影响,发现除中微子质量总和外,重子声学振荡(BAO)也显著受$ξ_ν$影响。结合EMPRESS BBN、Planck CMB和BOSS BAO数据的联合分析给出了更严格的约束$ξ_ν= 0.024 \pm 0.012$,这为能够产生大不对称性的紫外模型提供了约束。

英文摘要:

The primordial neutrino asymmetry leaves profound imprints on the evolution history of the universe, which can be constrained by cosmological observations, including Big Bang Nucleosynthesis (BBN), Cosmic Microwave Background (CMB), and Large-Scale Structure (LSS). We present comprehensive analysis on implications and constraints of the primordial neutrino asymmetry, based on a precise treatment of neutrino decoupling by solving the complete (anti)neutrino quantum kinetic equations in the Closed-Time-Path formalism. { Assuming the same primordial asymmetry $ξ_ν$ for all neutrino flavors,} the effective number of neutrinos $N_{\rm eff}$ and (anti)neutrino spectral distortions are calculated, and we find that the non-instantaneous decoupling correction is given by $δN_{\rm eff} = 0.0440 + 0.0102 \, ξ_ν^2$. Then we perform the state-of-the-art calculation for the abundance of light elements including (anti)neutrino spectral distortions, which indicate a positive asymmetry $0.032 \leq ξ_nu \leq 0.052$ from EMPRESS data. The implications of the neutrino asymmetry for the CMB and LSS are studied in detail, and we find that the Baryon Acoustic Oscillations (BAO) are also significantly affected by $ξ_νin addition to the sum of neutrino masses. A combined analysis with EMPRESS BBN, Planck CMB and BOSS BAO data yields a tighter constraint $ξ_ν= 0.024 \pm 0.012$, which provides constraints on UV models capable of producing large asymmetries.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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