发表机构
Princeton University; Oakland University; University of Michigan; Stanford University; SLAC National Accelerator Laboratory（普林斯顿大学; 奥克兰大学; 密歇根大学; 斯坦福大学; SLAC国家加速器实验室）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文研究反超局域性对暴胀平台模型的影响，开发评估方案并结合数值相对论代码发现其会阻碍暴胀或引发量子失控，且微调要求随暴胀能量降低而更严苛，不利于降张标比的常用方法。
AI 中文摘要
反超局域性指耦合爱因斯坦-标量场方程中空间梯度项相对于速度项的增长，是暴胀开始前减速膨胀的特征。此前数值相对论研究表明，反超局域性会阻止具有幂律暴胀子势的模型发生暴胀。本文中，我们证明，被认为是产生低于当前观测上限的张标比的最简单方式的平台形暴胀子势模型，尤其易受反超局域性效应影响，原因在于平台的平坦性，以及普朗克密度与平台势能之间约10个数量级的能量密度差。为研究该问题，我们开发了一种评估一般暴胀模型可行性的方案，并将其应用于平台势，使用此前已验证的数值相对论代码。我们发现，从一般初始条件出发，爱因斯坦方程中梯度项相对于非梯度项的增长，要么会阻止暴胀持续足够的e折叠数，要么会触发量子失控阶段。我们还表明，为避免这些问题所需的初始条件微调会随着暴胀能量尺度的降低而变得更严重，这不利于降低张标比的常用方法。
英文摘要
Anti-ultralocality refers to the growth of spatial gradient terms relative to velocity terms in the coupled Einstein--scalar field equations. It is a characteristic feature of decelerated expansion before the onset of inflation. Previous numerical relativity studies have shown that anti-ultralocality prevents the onset of inflation in models with power-law inflaton potentials. In this paper, we show that models with plateau-shaped inflaton potentials, which are considered to be the simplest way to generate a tensor-to-scalar ratio below current observational upper limits, are especially vulnerable to anti-ultralocality effects. The reasons are the flatness of the plateau and the energy density gap of $\sim 10$ orders of magnitude between the Planck density and the plateau potential energy. To study the problem, we develop a protocol for assessing the viability of inflationary models in general, and we apply it to a plateau potential using a previously validated numerical relativity code. We find that, starting from generic initial conditions, the growth of gradient terms in the Einstein equations relative to non-gradient terms either prevents inflation from lasting for enough $e$-folds or triggers a phase of quantum runaway. We show that the fine-tuning of initial conditions necessary to avoid these issues becomes more severe as the energy scale of inflation is made smaller, disfavoring common approaches for reducing the tensor-to-scalar ratio.
Comments14 pages, 5 figures
