Is imaginary Starobinsky model real?

Renata Kallosh,Bert Vercnocke,Wissam Chemissany,Andrei Linde

doi:10.1088/1475-7516/2014/07/053

Abstract

We investigate the recently proposed possibility of chaotic inflation with respect to the imaginary part of the field T in a supersymmetric embedding of the Starobinsky model. We show that the stage of rapid expansion driven by Im T in this model ends almost instantly, and the subsequent stages of inflation are driven by the real part of the field T, as in the standard Starobinsky model. Thus, the Starobinsky model and its supersymmetric generalizations remain disfavored by the recent BICEP2 data.

Highlights

During the last few years we witnessed several radically different trends in the development of inflationary cosmology
The Planck data revealed that the fNloLcal is as small as one could expect from the simplest inflationary models, so we were able to return to the investigation of more regular versions of inflationary theory
Such scenario leads to the same consequences as the Starobinsky model, i.e. to r ∼ 0.004, which is disfavored by BICEP2

Summary

Introduction

During the last few years we witnessed several radically different trends in the development of inflationary cosmology. The original version of the Starobinsky model was based on the investigation of Einstein gravity including the contribution from the conformal anomaly [4] The goals of this model were in a certain sense opposite to the goals of inflationary cosmology. A year later a different formulation of the supersymmetric version of the R + R2 was given by Cecotti, Ferrara, Porrati and Sabharwal in [12] in the context of a new minimal formulation It was shown in [9] that upon a dual transformation the higher derivative model depending only on a curvature superfield is given by the standard 2-derivative supergravity interacting with two chiral matter multiplets, T and C, see more recent and detailed discussion of this in [13], [14]. One real scalar field is available there and it leads only to Starobinsky model with low level of r, there are no other scalars which could be used as inflatons to increase r

Inflation

For b2

Towards chaotic inflation in a modified Cecotti model

Findings

Conclusions