Exact inflation in Einstein–Gauss–Bonnet gravity

Фомин, И. В.; Chervon, S. V.

doi:10.1134/s0202289317040090

Cited by 16 publications

(18 citation statements)

References 34 publications

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“…Even though the Gauss-Bonnet term alone, in the context of four dimensional physics, does not contribute to the gravitational field equations, the scalar coupling makes the Gauss-Bonnet term (and hence the field equations) non-trivial. Some aspects of this scalar coupled Gauss-Bonnet gravity in the context of early universe physics has been explored in [32][33][34][35][36][37][38][39][40][41][42][43] (for a set of earlier works in other alternative theories in the similar spirit, see ). Below we provide a brief discussion on the results obtained in these works.The inflationary paradigm has been explored in [36,37] only in the context of scalar coupled Gauss-Bonnet gravity, excluding the Einstein term.…”

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confidence: 99%

Inflation driven by Einstein-Gauss-Bonnet gravity

2018

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We have explicitly demonstrated that scalar coupled Gauss-Bonnet gravity in four dimension can have non-trivial effects on the early inflationary stage of our universe. In particular, we have shown that the scalar coupled Gauss-Bonnet term alone is capable of driving the inflationary stages of the universe without incorporating slow roll approximation, while remaining compatible with the current observations. Subsequently, to avoid the instability of the tensor perturbation modes we have introduced a self-interacting potential for the inflaton field and have shown that in this context as well it is possible to have inflationary scenario. Moreover it turns out that presence of the Gauss-Bonnet term is incompatible with the slow roll approximation and hence one must work with the field equations in the most general context. Finally, we have shown that the scalar coupled Gauss-Bonnet term attains smaller and smaller values as the universe exits from inflation. Thus at the end of the inflation the universe makes a smooth transition to Einstein Therefore most of the inflationary paradigms are driven by a scalar field with a non-trivial self-interacting potential in Einstein gravity.A natural pathway through which such a scalar field can enter the gravitational dynamics at the early universe is through the coupling of the field with the Gauss-Bonnet term. The Gauss-Bonnet term is the first non-trivial higher curvature correction to the Einstein-Hilbert action [27][28][29][30], leading to second order field equations and hence avoiding the Ostrogradsky instability [31]. Even though the Gauss-Bonnet term alone, in the context of four dimensional physics, does not contribute to the gravitational field equations, the scalar coupling makes the Gauss-Bonnet term (and hence the field equations) non-trivial. Some aspects of this scalar coupled Gauss-Bonnet gravity in the context of early universe physics has been explored in [32][33][34][35][36][37][38][39][40][41][42][43] (for a set of earlier works in other alternative theories in the similar spirit, see ). Below we provide a brief discussion on the results obtained in these works.The inflationary paradigm has been explored in [36,37] only in the context of scalar coupled Gauss-Bonnet gravity, excluding the Einstein term. While in [39,43], even though the Einstein term was essential, the self-interacting potential itself governs the inflation, having no effect of the Gauss-Bonnet term. On the other hand, in [32][33][34][35] both the self-interacting potential as well as the Gauss-Bonnet coupling for the inflaton field has been considered, but in the context of slow-roll approximation (see also [35,[40][41][42]98,99]). Thus non-trivial effects of the scalar coupled Gauss-Bonnet term in the Einstein-Hilbert action, in absence of self-interacting scalar potential in the context of inflationary paradigm has not been explored before. Besides, even when the self-interacting potential is added to the action, the relevant consequences of not incorporating the slow-roll approximation...

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confidence: 99%

Inflation driven by Einstein-Gauss-Bonnet gravity

2018

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“…To make possible a generation of exact solutions for inflation in 4D EGB cosmology and comparison with standard Friedmann cosmology let us define the new (generalized, in respect to that introduced in [24]) connection between the Hubble parameter H of standard inflation and the Hubble parameter H in the 4D EGB model…”

Section: Conformity Between Standard Friedmann and 4d Egb Cosmologymentioning

confidence: 99%

“…where C is an arbitrary constant. In the paper [24] we considered the case where C = 1/2, k = 0. With the representation (59) the equations (3)-(4) are reduced to the ones for the standardlike cosmology (6)- (7).…”

Section: Generation Of 4d Egb Exact Solutions From a Scale Factormentioning

confidence: 99%

“…For models with coupling function (59) we have ∆ N = N − N = 2C te t i a(t)dt, thus, difference between e-folds numbers depends on the dynamics and the value of constant C. Let us note also, that it is possible to generate the exact solutions for 4D EGB cosmology on the basis of exact solutions for standard cosmology in Friedmann universe for the cases k = 0 and k = 0 from the equations (59)-(61). This procedure for a spatially-flat Friedmann universe was proposed in the paper [24], the examples of exact solutions for open and closed Friedmann models one can find, for instance, in [25][26][27].…”

Section: Hdtmentioning

confidence: 99%

“…In the paper [24], we paid attention for two main problems: the estimation of the influence of the non-minimal coupling of the scalar field with the GB term on the cosmological dynamics and finding the effective technique of exact solutions constructions. Both these problems were successfully solved after finding the connection between the Hubble parameters H and H for standard scalar field cosmology and for scalar cosmology, based on EGB gravity with nonminimal coupling to a scalar field, correspondingly.…”

Section: Introductionmentioning

confidence: 99%

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