标题： 多场非最小耦合暴胀后的预热，I：协变形式主义与吸引子行为 显示英文标题

标题： Preheating after Multifield Inflation with Nonminimal Couplings, I: Covariant Formalism and Attractor Behavior

摘要： 这是三部分论文系列的第一篇，我们研究了涉及非最小耦合的多场暴胀模型的预加热阶段。 本文研究了这些模型在暴胀期间表现出的单场吸引子行为，并量化了其强度和参数依赖性。 我们进一步证明，强烈的单场吸引子行为在暴胀结束之后仍然持续。 因此，在这类模型中的预加热通常避免了典型影响最小耦合场多场模型的“去相位”现象，允许从振荡暴胀子凝聚态到耦合扰动的有效能量转移，覆盖了参数空间的大范围。 我们发展了一种双重协变形式来研究这类模型的预加热阶段，并识别出一些多场非最小耦合模型特有的特征，包括来自非平凡场空间流形产生的效应。 在第二篇和第三篇论文中，我们将应用这一形式来研究绝热和等曲率扰动放大如何随参数变化，突出显示几种不同的区域，取决于非最小耦合强度 $\xi_I$。 显示英文摘要

摘要： This is the first of a three-part series of papers, in which we study the preheating phase for multifield models of inflation involving nonminimal couplings. In this paper, we study the single-field attractor behavior that these models exhibit during inflation and quantify its strength and parameter dependence. We further demonstrate that the strong single-field attractor behavior persists after the end of inflation. Preheating in such models therefore generically avoids the "de-phasing" that typically affects multifield models with minimally coupled fields, allowing efficient transfer of energy from the oscillating inflaton condensate(s) to coupled perturbations across large portions of parameter space. We develop a doubly-covariant formalism for studying the preheating phase in such models and identify several features specific to multifield models with nonminimal couplings, including effects that arise from the nontrivial field-space manifold. In papers II and III, we apply this formalism to study how the amplification of adiabatic and isocurvature perturbations varies with parameters, highlighting several distinct regimes depending on the magnitude of the nonminimal couplings $\xi_I$.