Universality in generalized models of inflation

TL;DR

This paper explores the universal behavior of generalized inflation models with non-standard kinetic terms using Renormalization Group Equations, highlighting how different models can produce observable cosmological signatures consistent with current data.

Contribution

It introduces a formalism based on RGEs to classify inflationary models into universality classes and analyzes their observable predictions.

Findings

Inflation corresponds to slow evolution near a fixed point in the RGE framework.

Models with $c_s^2 eq 1$ can match current cosmological observations.

Universality classes naturally arise in the evolution of scalar fields with non-standard kinetic terms.

Abstract

We discuss the cosmological evolution of a scalar field with non standard kinetic term in terms of a Renormalization Group Equation (RGE). In this framework inflation corresponds to the slow evolution in a neighborhood of a fixed point and universality classes for inflationary models naturally arise. Using some examples we show the application of the formalism. The predicted values for the speed of sound $c_s$ and for the amount of non-Gaussianities produced in these models are discussed. In particular, we show that it is possible to introduce models with $c_s^2 \neq 1$ that can be in agreement with present cosmological observations.