Neutrino decoupling including flavour oscillations and primordial nucleosynthesis
Neutrino decoupling including flavour oscillations and primordial nucleosynthesis
复制标题
DOI：
10.1088/1475-7516/2020/12/015
复制
发表时间：
2020-08
影响因子：
6.4
通讯作者：
Julien Froustey;C. Pitrou;M. Volpe
中科院分区：
文献类型：
--
作者：
Julien Froustey;C. Pitrou;M. Volpe
我们重新审视早期宇宙中中微子与味道振荡的解耦。我们基于类似 BBGKY 的层次结构重新推导了确定中微子演化的量子动力学方程，并首次包含了完整的碰撞项，以及所有相关反应的对角线和非对角线项。我们关注化学势为零的情况并数值求解这些方程。我们还开发了一种基于物质基础绝热演化的近似方案。事实上，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，当与微分系统雅可比行列式的直接计算相结合时，它可以将数值积分加速两个数量级。近似数值方案对于更深入地了解中微子解耦的物理原理也很有用。包括等离子体热力学 QED 修正的最新结果，我们将中微子的有效数量更新为 Neff = 3.0440。最后，我们研究了中微子解耦过程中味道振荡对随后的原始核合成的影响。
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 Neff = 3.0440. Finally we study the impact of flavour oscillations during neutrino decoupling on the subsequent primordial nucleosynthesis.