标题： 无质量$φ^4$理论中的宇宙学关联函数和区域方法 显示英文标题

标题： Cosmological Correlators in massless $φ^4$-theory and the Method of Regions

摘要： 量子场在暴胀期间或在de~Sitter背景下的关联函数的环修正计算比在平空间中更具挑战性，因为模函数的形式更加复杂。 虽然在平空间中存在高度复杂的费曼积分方法，但类似的工具仍需为宇宙学关联函数开发。 然而，通常只关心它们的晚期时间极限。 我们引入区域展开法作为提取晚期时间极限的工具，并通过几个例子来说明，在de~Sitter空间中相互作用的、无质量的、最小耦合的标量场的情况。 特别是，我们考虑in-in关联函数$\langle\phi^2(\eta,q)\phi(\eta,k_1)\phi(\eta,k_2)\rangle$，其区域结构与Soft de Sitter有效理论中的异常维度和匹配系数相关。 显示英文摘要

摘要： The calculation of loop corrections to the correlation functions of quantum fields during inflation or in the de~Sitter background presents greater challenges than in flat space due to the more complicated form of the mode functions. While in flat space highly sophisticated approaches to Feynman integrals exist, similar tools still remain to be developed for cosmological correlators. However, usually only their late-time limit is of interest. We introduce the method-of-region expansion for cosmological correlators as a tool to extract the late-time limit, and illustrate it with several examples for the interacting, massless, minimally coupled scalar field in de~Sitter space. In particular, we consider the in-in correlator $\langle\phi^2(\eta,q)\phi(\eta,k_1)\phi(\eta,k_2)\rangle$, whose region structure is relevant to anomalous dimensions and matching coefficients in Soft de Sitter effective theory.