We consider a mechanism for producing a significant population of primordial black holes (PBHs) and an observable stochastic gravitational wave background (SGWB) within string theory inspired models of inflation. In this framework where inflaton is identified as a non-compact axion-like field, sub-leading non-perturbative effects can superimpose steep cliffs connected by smooth plateaus onto the underlying axion potential. In the presence of coupling to Abelian gauge fields, the motion of axion on the cliff-like region(s) of its potential triggers a localized production of one helicity state of gauge fields due to the temporary fast-roll of axion around such a feature. In this setup, primordial fluctuations sourced by vector fields exhibit a localized peak in momentum space corresponding to modes that exit the horizon when the axion velocity is maximal. As an application of this general mechanism, we present an example of axion inflation which both matches Planck observations at CMB scales and generates a population of light PBHs (M_PBH ≃ 10⁻¹³ M_⊙) that can account for all dark matter. In this scenario, the enhanced scalar fluctuations that leads to PBHs also generate an observable SGWB of induced origin at LISA scales. The amplitude and shape of the resulting GW signal inherits specific properties (such as non-Gaussianity and its shape) of its scalar sources that may allow us to distinguish this mechanism from other inflationary scenarios and astrophysical backgrounds. This GW signal together with an observation of PBH distribution at the corresponding scales can thus provide a window to the inflationary dynamics on scales much smaller than those probed by Cosmic Microwave Background (CMB) and Large Scale Structure (LSS) Measurements.

我们考虑了一种在字符串理论启发的通货膨胀模型内产生大量原始黑洞（PBH）和可观察到的随机重力波背景（SGWB）的机制。在这种将充气子标识为非紧凑型轴突场的框架中，次要的非扰动效应可以将由平滑高原连接的陡峭悬崖叠加到潜在的轴突势上。在存在耦合到阿贝尔规范场的情况下，由于轴突在这种特征周围的暂时快速滚动，轴突在其势势的悬崖状区域上的运动触发了一种规范度场的螺旋状态的局部产生。 。在此设置中，由矢量场产生的原始波动在动量空间中表现出局部峰值，该峰值对应于轴突速度最大时离开地平线的模式。作为此通用机制的应用，我们提供了一个轴距膨胀的示例，它既可以在CMB规模上与Planck观测值相匹配，又可以生成轻型PBH（M _PBH  ＆simeq; 10 ^-13  M _＆odot;），可以解决所有暗物质。在这种情况下，导致PBH的标量波动增加，也会在LISA尺度上生成可观察到的SGWB。产生的GW信号的幅度和形状继承了其标量源的特定属性（例如非高斯性及其形状），这可能使我们能够将这种机制与其他膨胀情景和天体物理学背景区分开。因此，该GW信号以及对相应尺度下PBH分布的观察可以为尺度上的膨胀动力学提供一个窗口，该尺度远小于由宇宙微波背景（CMB）和大规模结构（LSS）测量所探测到的尺度。