论文标题
中微子解耦，包括风味振荡和原始核合成
Neutrino decoupling including flavour oscillations and primordial nucleosynthesis
论文作者
论文摘要
我们通过风味振荡重新审视早期宇宙中中微子的脱钩。我们对基于Bbgky样层次结构确定中微子进化的量子动力学方程进行了重新绘制，并首次包括完整的碰撞项，并在所有相关反应中都具有on和off-Diagonal项。我们专注于零化学势的情况，并以数值求解这些方程。我们还根据此基础上的绝热进化制定了一个近似方案。实际上，振荡和宇宙学时间尺度之间的巨大差异允许考虑平均风味振荡，当与差分系统雅各布的直接计算结合使用时，可以将数值整合加快两个数量级加速。近似数值方案也有助于更多地了解中微子去耦的物理学。包括有关等离子热力学QED校正的最新结果，我们将有效数量的中微子更新为$ n _ {\ Mathrm {eff}}} = 3.0440 $。最后，我们研究了中微子解耦过程中风味振荡对随后原始核合成的影响。
We revisit the decoupling of neutrinos in the early universe with flavour oscillations. We rederive the quantum kinetic equations which determine the neutrino evolution based on a BBGKY-like hierarchy, and include for the first time the full collision term, with both on- and off-diagonal terms for all relevant reactions. We focus on the case of zero chemical potential and solve these equations numerically. We also develop an approximate scheme based on the adiabatic evolution in the matter basis. In fact, the large difference between the oscillations and cosmological time scales allows to consider averaged flavour oscillations which can speed up the numerical integration by two orders of magnitude, when combined with a direct computation of the differential system Jacobian. The approximate numerical scheme is also useful to gain more insight into the physics of neutrino decoupling. Including the most recent results on plasma thermodynamics QED corrections, we update the effective number of neutrinos to $N_{\mathrm{eff}} = 3.0440$. Finally we study the impact of flavour oscillations during neutrino decoupling on the subsequent primordial nucleosynthesis.
