Construction of inflationary scenarios with the Gauss–Bonnet term and nonminimal coupling

Pozdeeva, Ekaterina; Vernov, S. Yu.

doi:10.1140/epjc/s10052-021-09435-8

Cited by 29 publications

(12 citation statements)

References 110 publications

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“…(28). A direct comparison of the final expressions for the slow-roll indices ( 22)-( 27), and of the tensor spectral index (34) and the tensor-to-scalar ratio (33), with the expressions obtained in Ref. [17], can show the simplicity of the expressions obtained in the present work.…”

Section: Simplified Einstein-gauss-bonnet Inflation Frameworksupporting

confidence: 61%

“…[17], with φ f being the value of the scalar field at the end of the inflationary era, and φ i is the value of the scalar field at the beginning of the inflationary era, precisely at the first horizon crossing time instance. Essentially, the slow-roll indices ( 22)-( 27), the tensor spectral index (34) and the tensor-to-scalar ratio (33) are the main results of this work. We shall use this simplified framework to examine whether a viable phenomenology can be obtained.…”

Section: Simplified Einstein-gauss-bonnet Inflation Frameworkmentioning

confidence: 98%

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A Refined Einstein-Gauss-Bonnet Inflationary Theoretical Framework

Oikonomou

2021

Preprint

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We provide a refined and much more simplified Einstein-Gauss-Bonnet inflationary theoretical framework, which is compatible with the GW170817 observational constraints on the gravitational wave speed. As in previous works, the constraint that the gravitational wave speed is c 2 T = 1 in natural units, results to a constraint differential equation that relates the coupling function of the scalar field to the Gauss-Bonnet invariant ξ(φ) and the scalar potential V (φ). Adopting the slow-roll conditions for the scalar field and the Hubble rate, and in contrast to previous works, by further assuming that κ ξ ξ 1, which is motivated by slow-roll arguments, we succeed in providing much more simpler expressions for the slow-roll indices and for the tensor and scalar spectral indices and for the tensor-to-scalar ratio. We exemplify our refined theoretical framework by using an illustrative example with a simple power-law scalar coupling function ξ(φ) ∼ φ ν and as we demonstrate the resulting inflationary phenomenology is compatible with the latest Planck data. Moreover, this particular model produces a blue-tilted tensor spectral index, so we discuss in brief the perspective of describing the NANOGrav result with this model as is indicated in the recent literature.

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Section: Simplified Einstein-gauss-bonnet Inflation Frameworksupporting

confidence: 61%

Section: Simplified Einstein-gauss-bonnet Inflation Frameworkmentioning

confidence: 98%

A Refined Einstein-Gauss-Bonnet Inflationary Theoretical Framework

Oikonomou

2021

Preprint

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“…Where we get the overall modification factor of e −D in the standard expression of primordial GW power spectrum given by Eqn. (67).…”

Section: F Primordial Gravitational Waves In Einstein Gravitymentioning

confidence: 99%

“…For EGB models, compatible with GW170817, it was first noted in [75], that the factor D, is vanishingly small, O(10 −60 ), when the integral ( 74) is calculated from present day up to the reheating era, z ∼ 10 6 . Thus, the factor of e −2D becomes unity, and we can use the standard expression of power spectrum given by (67).…”

Section: F Primordial Gravitational Waves In Einstein Gravitymentioning

confidence: 99%

A Case Study of Small Field Inflationary Dynamics in the Einstein-Gauss Bonnet Framework in the Light of $GW170817$

Gangopadhyay¹,

Khan²,

Yogesh³

2022

Preprint

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We study two of the most theoretically promising models of inflation, namely the Natural inflation and the Mutated Hilltop inflation, in the Einstein-Gauss Bonnet(EGB) gravity framework. In this work, we try to explore these models in EGB framework, keeping the observational constraint from GW 170817 on the speed of gravitational wave to be equal to the speed of light. This has direct implication on the non-minimal coupling to the Gauss-Bonnet invariant in the action. Thus, the effective potential gets new features. We have not only analysed the inflationary dynamics, but also the reheating dynamics and finally the corresponding energy spectrum of the gravitational wave.

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“…When using the notion of the effective potential[27], it is possible to get an analogue of Eq. (40) in more general models with the scalar field non-minimally coupled to the Ricci scalar and the Gauss-Bonnet term[28,29].…”

mentioning

confidence: 99%

Analytic extensions of Starobinsky model of inflation

Ivanov,

Ketov,

Pozdeeva

et al. 2021

Preprint

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We propose several extensions of the Starobinsky model of inflation, which obey all observational constraints on the inflationary parameters, by demanding that both the inflaton scalar potential in the Einstein frame and the F (R) gravity function in the Jordan frame have the explicit dependence upon fields and parameters in terms of elementary functions. All our models are continuously connected to the original Starobinsky model via changing the parameters. We modify the Starobinsky (R + R 2 ) model by adding an R 3 -term, an R 4term, and an R 3/2 -term, respectively, and calculate the scalar potentials, the inflationary observables and the allowed limits on the deformation parameters in all these cases. We also deform the scalar potential of the Starobinsky model in the Einstein frame, in powers of y = exp − 2 3 φ/M P l , where φ is the canonical inflaton (scalaron) field, calculate the corresponding F (R) gravity functions in the two new cases, and find the restrictions on the deformation parameters in the lowest orders with respect to the variable y that is physically small during slow-roll inflation.

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Construction of inflationary scenarios with the Gauss–Bonnet term and nonminimal coupling

Cited by 29 publications

References 110 publications

A Refined Einstein-Gauss-Bonnet Inflationary Theoretical Framework

A Refined Einstein-Gauss-Bonnet Inflationary Theoretical Framework

A Case Study of Small Field Inflationary Dynamics in the Einstein-Gauss Bonnet Framework in the Light of $GW170817$

Analytic extensions of Starobinsky model of inflation

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