由快速演化状态方程生成标度不变微扰
Generating Scale-Invariant Perturbations from Rapidly-Evolving Equation of State
摘要：
最近，我们介绍了一个ekpyrotic模型的基础上，一个单一的，规范的标量场，产生近规模不变的曲率波动，通过一个纯粹的“绝热机制”，其中的背景演化是一个动态吸引子。尽管产生涨落的物理机制完全不同，但两点函数与暴胀是相同的。在本文中，我们将进一步探讨这一概念，特别关注非高斯性和量子修正的问题。我们发现，与通货膨胀的简并在三点的水平被打破：对于最简单的情况下，指数势，三点振幅是强烈的规模依赖，导致在小尺度上的微扰理论的崩溃。然而，我们表明，微扰击穿可以绕过-和林德等人提出的所有问题。（arXiv：0912.0944）可以解决-通过改变电位，使功率在小尺度上被抑制。由此产生的范围内的近尺度不变，高斯模式可以多达12个e倍，足以跨越尺度探测微波背景和大尺度结构观测。在较小的尺度上，光谱不是尺度不变的，但在观测上是可以接受的。
英文摘要：
Recently, we introduced an ekpyrotic model based on a single, canonical scalar field that generates nearly scale invariant curvature fluctuations through a purely "adiabatic mechanism" in which the background evolution is a dynamical attractor. Despite the starkly different physical mechanism for generating fluctuations, the two-point function is identical to inflation. In this paper, we further explore this concept, focusing in particular on issues of non-gaussianity and quantum corrections. We find that the degeneracy with inflation is broken at three-point level: for the simplest case of an exponential potential, the three-point amplitude is strongly scale dependent, resulting in a breakdown of perturbation theory on small scales. However, we show that the perturbative breakdown can be circumvented -- and all issues raised in Linde et al. (arXiv:0912.0944) can be addressed -- by altering the potential such that power is suppressed on small scales. The resulting range of nearly scale invariant, gaussian modes can be as much as twelve e-folds, enough to span the scales probed by microwave background and large scale structure observations. On smaller scales, the spectrum is not scale invariant but is observationally acceptable.
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