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A precision calculation of relic neutrino decoupling
Journal of Cosmology and Astroparticle Physics ( IF 6.4 ) Pub Date : 2020-08-05 , DOI: 10.1088/1475-7516/2020/08/012
Kensuke Akita , Masahide Yamaguchi

We study the distortions of equilibrium spectra of relic neutrinos due to the interactions with electrons, positrons, and neutrinos in the early Universe. We solve the integro-differential kinetic equations for the neutrino density matrix, including three-flavor oscillations and finite temperature corrections from QED up to the next-to-leading order $\mathcal{O}(e^3)$ for the first time. In addition, the equivalent kinetic equations in the mass basis of neutrinos are directly solved, and we numerically evaluate the distortions of the neutrino spectra in the mass basis as well, which can be easily extrapolated into those for non-relativistic neutrinos in the current Universe. In both bases, we find the same value of the effective number of neutrinos, $N_{\rm eff} = 3.044$, which parameterizes the total neutrino energy density. The estimated error for the value of $N_{\rm eff}$ due to the numerical calculations and the choice of neutrino mixing parameters would be at most 0.0005.

中文翻译:

一种残余中微子解耦的精度计算

我们研究了早期宇宙中由于与电子、正电子和中微子的相互作用而导致的残余中微子平衡光谱的畸变。我们首次求解了中微子密度矩阵的积分微分动力学方程,包括从 QED 到次领先阶次的三味振荡和有限温度校正 $\mathcal{O}(e^3)$ . 此外,我们直接求解了中微子质量基中的等效动力学方程,并且我们也对质量基中的中微子谱的畸变进行了数值评估,这可以很容易地外推到当前宇宙中非相对论中微子的畸变中. 在这两种基础上,我们发现中微子的有效数量相同,$N_{\rm eff} = 3.044$,它参数化了总中微子能量密度。
更新日期:2020-08-05
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