Observational constraints on slow-roll inflation coupled to a Gauss-Bonnet term

Abstract

We study slow-roll inflation with a Gauss-Bonnet term that is coupled to an inflaton field nonminimally. We investigate the inflationary solutions for a specific type of the nonminimal coupling to the GaussBonnet term and inflaton potential both analytically and numerically. We also calculate the observable quantities such as the power spectra of the scalar and tensor modes, the spectral indices, the tensor-to-scalar ratio, and the running spectral indices. Finally, we constrain our result with the observational data by Planck and BICEP2 experiment.

Constraining scalar-Gauss-Bonnet inflation by reheating, unitarity, and Planck data

“…At this stage let us comment on the differences between the analyses that are present in existing literature on Gauss-Bonnet inflation [8,9], [10] and in our paper. Two notable differences are the detail analysis of constraints coming from the consideration of the reheating phenomena and the unitarity analysis at the tree level scattering amplitude specifically for large Gauss-Bonnet coupling parameter.…”

“…Therefore, small but finite value of β improves the model by reducing the value of r. In Fig. (6), we have considered two chaotic models for β = (10,2000), and plotted the possible values of N re and T re within the range of scalar spectral index 0.978 > n s > 0.9475. For all the plots we considered four discreet set of values of the equation of state parameter (ω re1 , ω re2 ) = (−1/3, 0, 2/3, 1) during reheating.…”

“…Two notable differences are the detail analysis of constraints coming from the consideration of the reheating phenomena and the unitarity analysis at the tree level scattering amplitude specifically for large Gauss-Bonnet coupling parameter. In [10] the authors have considered scalar-Gauss-Bonnet inflation with the same type of inflaton potential and the Gauss-Bonnet coupling. As long as the inflationary observables (n s , r) are concerned, our analysis so far does not have much difference except the fact that we have considered the latest cosmological observation from PLANCK.…”

“…In this paper, we will consider specific class of models where a scalar field couples with the Gauss-Bonnet term non-minimally. There have been a lot of studies on the implications of scalar coupled Gauss-Bonnet term in the context of inflationary scenario [8][9][10] 1 . In the context of dark energy model, Gauss-Bonnet term has also been considered [11].…”

Slow-roll inflation from massive vector fields non-minimally coupled to gravity

“…These equations are similar to those studied in models of inflation with scalar fields coupled to the Gauss-Bonnet invariant [Neupane et al (2006) in the scalar field equations), we can calculate for this model the number of e-folds and the observable quantities such as the power spectra of the scalar and tensor modes, the spectral indices, the tensor-to-scalar ratio and the running spectral indices. For example, considering the slow-roll conditions (see [Guo et al (2010)] and [Koh et al (2014)…”