The Non-Adiabatic Pressure Perturbation and Non-Canonical Kinetic Terms in Multifield Inflation

TL;DR

This paper investigates how non-adiabatic pressure perturbations evolve during multifield inflation, highlighting the significant impact of canonical and non-canonical kinetic terms on their behavior and final amplitude.

Contribution

It provides a numerical analysis of non-adiabatic pressure perturbations in multifield inflation models with various kinetic term configurations, including canonical, coupled, and DBI fields.

Findings

Non-adiabatic pressure evolution varies with kinetic term type.

Final amplitude depends strongly on kinetic term structure.

Non-canonical kinetic terms significantly influence perturbation dynamics.

Abstract

The evolution of the non-adiabatic pressure perturbation during inflation driven by two scalar fields is studied numerically for three different types of models. In the first model, the fields have standard kinetic terms. The other two models considered feature non-canonical kinetic terms; the first containing two fields which are coupled via their kinetic terms, and the second where one field has the standard kinetic term with the other field being a DBI field. We find that the evolution and the final amplitude of the non-adiabatic pressure perturbation depends strongly on the kinetic terms.