Infrared effects in inflationary correlation functions

TL;DR

This paper reviews the different types of infrared divergences in inflationary correlation functions, their origins, and the methods developed to handle these divergences in cosmological calculations.

Contribution

It provides a comprehensive overview of the infrared effects in inflationary models, clarifying their nature and discussing techniques to address them.

Findings

Identification of three types of infrared divergences: secular, box-cutoff, and quantum logarithms.

Analysis of the origins and implications of each divergence type.

Discussion of methods developed to regularize and interpret these divergences.

Abstract

In this article, I briefly review the status of infrared effects which occur when using inflationary models to calculate initial conditions for a subsequent hot, dense plasma phase. Three types of divergence have been identified in the literature: secular, "time-dependent" logarithms, which grow with time spent outside the horizon; "box-cutoff" logarithms, which encode a dependence on the infrared cutoff when calculating in a finite-sized box; and "quantum" logarithms, which depend on the ratio of a scale characterizing new physics to the scale of whatever process is under consideration, and whose interpretation is the same as conventional field theory. I review the calculations in which these divergences appear, and discuss the methods which have been developed to deal with them.