We investigate the large curvature perturbations which can lead to the formation of primordial black holes (PBHs) in the context of no-scale supergravity. Our study does not depend on any exotic scenario, such as scalar potentials with inflection points or bulks, and aims to avoid the fine-tuning of model parameters to achieve the formation of PBHs. This formation relies on the quantum fluctuations of a light spectator stochastic field after the inflationary period. Our analysis is based on the symmetry, considering both the inflaton and the spectator field. Specifically, we examine existing no-scale models with Starobinsky-like scalar potentials that are consistent with observable constraints on inflation from measurements of the cosmic microwave background (CMB). These models involve two chiral fields: the inflaton and the modulus field. We propose a novel role for the modulus field as a spectator field, responsible for generating PBHs. Our hypothesis suggests that while the inflaton field satisfies the CMB constraints of inflation, it is the modulus field acting as the spectator that leads to large curvature perturbations, capable to explain the production of PBHs. Additionally, we prioritize retaining the inflationary constraints from the CMB through the consideration of spectator fluctuations. Therefore, by exploring the relationship between these fields within the framework of the symmetry, our aim is to unveil their implications for the formation of PBHs.

中文翻译：

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来自无尺度超重力和观众场的大曲率波动


我们研究了在无尺度超重力背景下可能导致原初黑洞（PBH）形成的大曲率扰动。我们的研究不依赖于任何奇异的场景，例如具有拐点或体积的标量势，并且旨在避免模型参数的微调以实现PBH的形成。这种形成依赖于暴胀期后光观察随机场的量子涨落。我们的分析基于对称性，同时考虑了暴胀子和观察场。具体来说，我们检查了现有的具有类 Starobinsky 标量势的无尺度模型，该模型与宇宙微波背景 (CMB) 测量中可观察到的膨胀约束一致。这些模型涉及两个手性场：暴胀场和模量场。我们提出了模数场作为观众场的新角色，负责生成 PBH。我们的假设表明，虽然暴胀场满足暴胀的 CMB 约束，但充当旁观者的模量场会导致大曲率扰动，从而能够解释 PBH 的产生。此外，我们优先考虑通过考虑观众波动来保留 CMB 的通胀约束。因此，通过在对称性框架内探索这些场之间的关系，我们的目的是揭示它们对PBH形成的影响。