论文标题
物质的中微子振荡：从微观到宏观描述
Neutrino oscillations in matter: from microscopic to macroscopic description
论文作者
论文摘要
非均匀物质中的中微子风味传播通过具有坐标依赖性电势的Schrödinger样进化方程来描述。在该方程式的所有推导中，都假定该电位是由于中微子在物质成分上的相干向前散射引起的，它是坐标的连续函数，它在中微子de Broglie波长的距离上缓慢变化。这种默认的假设已经执行了微观电位的某种平均值（考虑到散射器的离散性质）。但是，必须将平均值应用于整个微观演化方程，而不仅仅是电位。这样的平均值从未明确进行。我们通过考虑通过适当的平均程序从微观中微子进化方程式过渡到宏观中微子进化方程来填补这一空白。我们讨论了与此过程有关的一些微妙之处，并建立了标准宏观演化方程的适用性域。特别是，这使我们能够回答一个问题，即在物质中中微子风味演变的标准理论中，可以考虑稀有培养基中的中微子传播（例如\ \ \ \ \ \ \ \ \ \ \ \ \低密度气体或星际媒介）的问题。
Neutrino flavour transmutations in nonuniform matter are described by a Schrödinger-like evolution equation with coordinate-dependent potential. In all the derivations of this equation it is assumed that the potential, which is due to coherent forward scattering of neutrinos on matter constituents, is a continuous function of coordinate that changes slowly over the distances of the order of the neutrino de Broglie wavelength. This tacitly assumes that some averaging of the microscopic potential (which takes into account the discrete nature of the scatterers) has been performed.The averaging, however, must be applied to the microscopic evolution equation as a whole and not just to the potential. Such an averaging has never been explicitly carried out. We fill this gap by considering the transition from the microscopic to macroscopic neutrino evolution equation through a proper averaging procedure. We discuss some subtleties related to this procedure and establish the applicability domain of the standard macroscopic evolution equation. This, in particular, allows us to answer the question of when neutrino propagation in rarefied media (such as e.g.\ low-density gases or interstellar or intergalactic media) can be considered within the standard theory of neutrino flavour evolution in matter.
