Relic neutrino decoupling including flavour oscillations
Relic neutrino decoupling including flavour oscillations
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DOI：
10.1016/j.nuclphysb.2005.09.041
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发表时间：
2005-06
期刊：
影响因子：
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通讯作者：
G. Mangano;G. Miele;S. Pastor;T. Pinto;O. Pisanti;P. Serpico
中科院分区：
文献类型：
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作者：
G. Mangano;G. Miele;S. Pastor;T. Pinto;O. Pisanti;P. Serpico
在早期宇宙中，当电子-正电子对湮灭时，中微子会发生轻微耦合，并将它们的熵转移给光子。这个过程导致中微子光谱的非热畸变，这种畸变取决于中微子的味道，对νethan来说比对νμ或ντ更大。通过求解中微子谱的动量相关动力学方程，研究了三中微子味振荡对中微子退耦过程的影响。我们发现振荡并没有从本质上改变中微子能量密度的总变化，以中微子的有效数计算，Neff=3.046，而对原醛4 He产生的微小影响增加了O（20%），高达2.1×10−4。这些结果是稳定的中微子混合参数目前有利的区域内。
In the early universe, neutrinos are slightly coupled when electron–positron pairs annihilate transferring their entropy to photons. This process originates non-thermal distortions on the neutrino spectra which depend on neutrino flavour, larger for νethan for νμor ντ. We study the effect of three-neutrino flavour oscillations on the process of neutrino decoupling by solving the momentum-dependent kinetic equations for the neutrino spectra. We find that oscillations do not essentially modify the total change in the neutrino energy density, giving Neff=3.046 in terms of the effective number of neutrinos, while the small effect over the production of primordial4He is increased by O(20%), up to 2.1×10−4. These results are stable within the presently favoured region of neutrino mixing parameters.