Nonperturbative infrared enhancement of nonGaussian correlators in de Sitter space

Understand

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.