Anisotropic inflation with derivative couplings

Jonathan Holland,Sugumi Kanno,Ivonne Zavala

doi:10.1103/physrevd.97.103534

Jonathan Holland, Sugumi Kanno + Show 1 more

Open Access

https://doi.org/10.1103/physrevd.97.103534

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Abstract

We study anisotropic inflationary solutions when the inflaton and its derivative couple to a vector field. This type of coupling is motivated by D-brane inflationary models, in which the inflaton, and a vector field living on the D-brane, couple disformally (derivatively). We start by studying a phenomenological model where we show the existence of anisotropic solutions and demonstrate their stability via a dynamical system analysis. Compared to the case without a derivative coupling, the anisotropy is reduced and thus can be made consistent with current limits, while the value of the slow-roll parameter remains almost unchanged. We also discuss solutions for more general cases, including D-brane like couplings.

Highlights

The most recent data on the cosmic microwave background radiation temperature fluctuations [1,2] favor the simplest inflationary scenario to provide their origin
We have studied anisotropic inflationary solutions where the inflaton couples to a vector field derivatively
This coupling is motivated by D-brane inflationary models, where the D-brane features a vector on its world volume, and couples derivatively to the brane’s position, the inflaton. Such couplings parametrize generic inflaton-matter couplings, which may be relevant in studies of the inflationary universe as a cosmological collider [15]. They appear in the Effective Field Theory (EFT) of anisotropic inflation [16,17]

Summary

INTRODUCTION

The most recent data on the cosmic microwave background radiation temperature fluctuations [1,2] favor the simplest inflationary scenario to provide their origin. The authors of [7] found the first working model (free from ghosts) of inflation with a vector field that can produce persistent anisotropy in the background spacetime This brought forward the interesting possibility that light gauge fields may affect cosmological observations by generating some observable amount of statistical anisotropy (for reviews on anisotropic inflation see [4,5,6]). Fðφ; XÞ represents a general parametrization of a generic inflaton-matter coupling This has recently been used in studies of the inflationary universe as a cosmological collider [15]. Motivated by the D-brane scenario and the more generic nature of a derivative coupling between the inflaton and a vector field (and even more generally, with matter), in this paper we study anisotropic inflation with derivative couplings. V with a discussion of our results and prospects for future work

SCALAR-VECTOR-TENSOR ACTION WITH GENERAL DERIVATIVE COUPLINGS

ANISOTROPIC POWER-LAW INFLATION WITH DERIVATIVE COUPLINGS

Stability of the anisotropic solutions