程函近似下多组分宇宙流体中的恢复传播子
Resummed propagators in multi-component cosmic fluids with the eikonal approximation
摘要：
我们引入程函近似来研究宇宙流体的大尺度运动对其小尺度演化的影响。这种方法包括将长波长位移场的影响收集到单个或有限数量的随机变量中，其统计特性可以从初始条件计算。对于单一的暗物质流体，我们表明，我们可以恢复重整化微扰理论的非线性传播子。这些是在不需要假设位移场遵循线性理论的情况下获得的。然后我们将程函近似推广到许多流体。特别是，我们研究了两个非相对论分量的情况下，我们推导出它们的图解传播等密度模式的存在。与绝热情况不同，在绝热情况下，只有小尺度模式的相位受大尺度平流场的影响，等密度模式也改变小尺度上的振幅。我们明确地解决了冷暗物质重子混合的情况下，发现等密度模式诱导只有很小的修正的图形传播。
英文摘要：
We introduce the eikonal approximation to study the effect of the large-scale motion of cosmic fluids on their small-scale evolution. This approach consists in collecting the impact of the long-wavelength displacement field into a single or finite number of random variables, whose statistical properties can be computed from the initial conditions. For a single dark matter fluid, we show that we can recover the nonlinear propagators of renormalized perturbation theory. These are obtained with no need to assume that the displacement field follows the linear theory. Then we extend the eikonal approximation to many fluids. In particular, we study the case of two non-relativistic components and we derive their resummed propagators in the presence of isodensity modes. Unlike the adiabatic case, where only the phase of small-scale modes is affected by the large-scale advection field, the isodensity modes change also the amplitude on small scales. We explicitly solve the case of cold dark matter-baryon mixing and find that the isodensity modes induce only very small corrections to the resummed propagators.
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