标题： 德西特空间中非高斯关联的非微扰红外增强 显示英文标题

标题： Nonperturbative infrared enhancement of nonGaussian correlators in de Sitter space

摘要： 我们在大N极限下计算了德西特空间中轻量O(N)标量场的四点关联函数。 对于超视界动量模式，红外效应显著增强了环图贡献的大小。 我们发现，在深红外极限下，这些环图贡献与树图贡献处于同一数量级。 树图的动量结构，特征为接触项，被一个数量级为一的因子重整化。 此外，环图贡献产生了一个新的动量结构，特征为交换图，对应于有效复合标量自由度的交换。 显示英文摘要

摘要： We compute the four-point correlation function of a light O(N) scalar field in de Sitter space in the large-N limit. For superhorizon momentum modes, infrared effects strongly enhance the size of loop contributions. We find that in the deep infrared limit, the latter are of the same order as the tree-level one. The tree-level momentum structure, characteristic of a contact term, gets renormalized by a factor of order unity. In addition loop contributions give rise to a new momentum structure, characteristic of an exchange diagram, corresponding to the exchange of an effective composite scalar degree of freedom.