Power-law inflation with minimal and nonminimal coupling

Bairagi, Mithun; Choudhuri, Amitava

doi:10.1140/epjp/i2018-12349-6

Cited by 7 publications

(7 citation statements)

References 55 publications

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“…The Planck satellite is unable to measure such a small value of non-Gaussianity. Contrarily, the non-minimal coupled case [13,14] supports Planck-2015 [15] and Planck-2018 [16] released data that suggest a nearly scale-invariant power spectrum with a large non-Gaussian power spectrum ( f NL ? 1).…”

Section: Introductionsupporting

confidence: 60%

“…There are numerous versions of the inflationary scenario, which basically differ in the form of the scalar field potential causing the inflation. Some of the most frequently employed potentials are exponential potential [36][37][38][39], power-law potential [14,40] and inverse power-law potential [41]. We consider the potential in the following general form…”

Section: Introductionmentioning

confidence: 99%

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Exact Bianchi type-I inflationary model with non-minimally coupled scalar field

Bairagi

2023

Phys. Scr.

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In the present work, we try to build up an inflationary model within the framework of Bianchi type-I spacetime using a non-minimally coupled, homogeneous, self-interacting canonical scalar field. Specifically, using the Lie symmetry method, we are able to find some novel exact solutions to the Einstein field equations by assuming a power-law relationship between the scalar field and average scale factor. These symmetry-based solutions have been used to derive the values of some important parameters of the anisotropic universe. In this anisotropic model, we find that the volume of space expands with time in an inflationary scenario, depicting the Universe's accelerating phases. An important characteristic of this model is that it initially represents anisotropic spacetime and then isotropizes the spacetime as time goes on, which favors recent cosmological observations.

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Section: Introductionsupporting

confidence: 60%

Section: Introductionmentioning

confidence: 99%

Exact Bianchi type-I inflationary model with non-minimally coupled scalar field

Bairagi

2023

Phys. Scr.

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“…[15,16]. On the other hand, it has also been exhaustively investigated other different aspects of inflationary cosmology in the presence of non-minimal coupling such as for JCAP08(2019)029 example the phase-space analysis [17,18], slow-roll approximation and conformal transformation techniques [19][20][21], power-law inflation [22][23][24], and non-Gaussianities [25][26][27]. Also, the consequences of general non-minimal couplings for inflation have also been investigated in the framework of scalar-tensor theories, in the so-called extended and hyper-extended inflation [28][29][30][31][32][33][34][35][36].…”

Section: Introductionmentioning

confidence: 99%

Slow-roll inflation in generalized scalar-torsion gravity

Gonzalez-Espinoza

Otalora

Videla

et al. 2019

J. Cosmol. Astropart. Phys.

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We study the dynamics of inflation in a generalized scalar-torsion gravity scenario by assuming a canonical scalar field non-minimally coupled to torsion with a Galileon-type self-interaction. After obtaining the field equations for a flat FRW background, we derive the second order action for both scalar and tensor perturbations to compute the power spectra of primordial fluctuations. As particular models, we studied at first, a power-law form of coupling function F (x) = 1 + ξx 2 /2, with x ≡ φ/M pl , and a monomial scalar field potential V (x) = λx n /n which is ruled out by current observational data for n ≥ 2. Under slow-roll approximation we obtain analytical expressions for the background as well as perturbative dynamics, and we show that the predictions of the model are consistent with current Planck 2018 constraints on the spectral index n s and the tensor-to-scalar ratio r through the n s − r plane. Accordingly, this model is in agreement with current observational bounds only within the 95% C.L. region in the case of chaotic quadratic inflation (n = 2), whereas that for the other monomial potentials such as n = 4/3, n = 1 and n = 2/3, it is found that they are even more favoured, overlapping their results with the 68% C.L. region from last Planck data. Secondly, we studied a model in which the presence of both non-minimal coupling to gravity and the Galileon non-linear self-interaction γ(∂φ) 2 φ leads to a suppression of the tensor-to-scalar ratio compared to those predicted in the standard scenario, then predicting 0.024 r 0.069. This result allows us to reconcile chaotic quadratic inflation with current Planck data up to the 68% C.L. region. In despite of this, next generation CMB experiments such as BICEP3 or LiteBIRD are expected to put stronger constraints, making possible to either support this model or rule it out.

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“…To discriminate among the different components that may be responsible for the present acceleration of the universe [74,75], two new geometrical parameters, termed as the statefinder parameters, which depend on the nature of the space-time metric, were introduced by Sahni et al [76]. These parameters are usually denoted by r and s, but here, we will denote them by and .…”

Section: A Power Law Solution For a Monomial Potentialmentioning

confidence: 99%

Studies on modified power law inflation

Paul¹,

Sengupta²,

Ray³

2023

Chinese Phys. C

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We study power law inflation (PLI) with a monomial potential and find a novel exact solution. It is well known that conventional PLI with exponential potential is inconsistent with the Planck data. Unlike the standard PLI, present model does not suffer from graceful exit problem and it agrees fairly well with recent observations. We have calculated the spectral index and the tensor-to-scalar ratio which are in very good agreement with recent observational data and also comparable with other modified inflationary models. A technique has been used which shows that the large cosmological constant reduces with expansion of the Universe in case of the power law inflation. The coupling of the inflaton with gravitation is the main point in this technique. The basic assumption here is that the two metric tensors in the gravitational and the inflaton parts correspond to different conformal frames which is in contradiction with the conventional power law inflation where the inflaton directly coupled with the background metric tensor. This fact has direct application to different dark energy models and assisted quintessence theory.

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Power-law inflation with minimal and nonminimal coupling

Cited by 7 publications

References 55 publications

Exact Bianchi type-I inflationary model with non-minimally coupled scalar field

Exact Bianchi type-I inflationary model with non-minimally coupled scalar field

Slow-roll inflation in generalized scalar-torsion gravity

Studies on modified power law inflation

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