Power-law plateau and inverse symmetric inflation

2018 ◽  
Vol 27 (08) ◽  
pp. 1850087 ◽  
Author(s):  
Abdul Jawad ◽  
Shahid Chaudhary
Keyword(s):  
Scalar Field ◽  
Power Spectrum ◽  
Spectral Index ◽  
Power Law ◽  
Field Model ◽  
Chaplygin Gas ◽  
Generalized Chaplygin Gas ◽  
Planck Data ◽  
Inflationary Parameters ◽  
Ratio Versus

Warm generalized Chaplygin gas inflation is being studied by assuming power-law plateau and inverse symmetric potentials with standard scalar field model. We consider strong dissipative regime with generalized dissipative coefficient and extract the various inflationary parameters such as scalar power spectrum, spectral index, tensor-to-scalar ratio and running of spectral index. It is found that both inflationary potentials favor the strong dissipative regime. Also, we construct the [Formula: see text]–[Formula: see text] (running of spectral index versus spectral index) and [Formula: see text]–[Formula: see text] (tensor-to-scalar ratio versus spectral index) planes and found that the trajectories of these planes favor WMAP 7 [Formula: see text] WMAP 9 and latest Planck data.

Shaft potential inspired warm inflation

2017 ◽  
Vol 14 (06) ◽  
pp. 1750088 ◽  
Author(s):  
Abdul Jawad ◽  
Amara Ilyas ◽  
Sarfraz Ahmad
Keyword(s):  
Scalar Field ◽  
Spectral Index ◽  
Power Spectra ◽  
Spectral Indices ◽  
Tensor Power ◽  
Planck Data ◽  
Warm Inflation ◽  
Slow Roll ◽  
Scalar Spectral Index ◽  
Inflationary Parameters

We discuss the warm inflation in the presence of shaft potential [Formula: see text], tachyon scalar field and the generalized form of dissipative coefficient [Formula: see text]. In this respect, we investigate the inflationary parameters (slow-roll parameters, number of e-folds, scalar-tensor power spectra, spectral indices, tensor-to-scalar ratio and running of scalar spectral index) in both strong and weak dissipative regimes. It is interesting to mention that our inflationary parametric results (tensor-scalar ratio, spectral index and running of spectral) are consistent with the recent observational data such as BICEP[Formula: see text], WMAP[Formula: see text] and latest Planck data.

Attractor inflationary solutions in braneworld scenario

2020 ◽  
pp. 2050117
Author(s):  
Saba Qummer ◽  
Abdul Jawad ◽  
M. Younas
Keyword(s):  
Cosmological Parameters ◽  
Energy Condition ◽  
High Energy ◽  
Chaplygin Gas ◽  
Index Formula ◽  
Generalized Chaplygin Gas ◽  
Planck Data ◽  
Strongly Agree ◽  
Generalized Cosmic Chaplygin Gas ◽  
Inflationary Parameters

This paper is devoted to discuss the attractor solutions of inflationary Chaplygin gas models such as generalized Chaplygin gas, modified Chaplygin gas and generalized cosmic Chaplygin gas in the framework of Randall–Sundrum type II braneworld scenario. We investigate the inflationary parameters like scalar spectral index [Formula: see text], tensor to scalar ratio [Formula: see text], and the running of scalar index [Formula: see text] as a function of e-folding numbers [Formula: see text] in the presence of attractor: [Formula: see text]. We evaluate and reformulate these parameters under high energy condition. In this inflationary scenario, we develop [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] planes. We also found that these cosmological parameters and perturbation strongly agree with the recent Planck data 2018 for considered Chaplygin gas models instead of [Formula: see text] in case of generalized cosmic Chaplygin gas.

scholarly journals Power spectrum in the Chaplygin gas model: tachyonic, fluid and scalar field representations

2009 ◽  
Vol 42 (4) ◽  
pp. 839-849 ◽  
Author(s):  
Carlos Eduardo Magalhães Batista ◽  
Júlio Cesar Fabris ◽  
Masaaki Morita
Keyword(s):  
Scalar Field ◽  
Power Spectrum ◽  
Chaplygin Gas

scholarly journals NEW HOLOGRAPHIC CHAPLYGIN GAS MODEL OF DARK ENERGY

2011 ◽  
Vol 20 (03) ◽  
pp. 281-297 ◽  
Author(s):  
M. MALEKJANI ◽  
A. KHODAM-MOHAMMADI
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Chaplygin Gas ◽  
Accelerated Expansion ◽  
Linear Perturbation ◽  
Generalized Chaplygin Gas ◽  
Infrared Cutoff ◽  
Scalar Field Models ◽  
Linear Perturbation Theory ◽  
Limiting Case

In this work, we investigate the holographic dark energy model with a new infrared cutoff (new HDE model), proposed by Granda and Oliveros. Using this new definition for the infrared cutoff, we establish the correspondence between the new HDE model and the standard Chaplygin gas (SCG), generalized Chaplygin gas (GCG) and modified Chaplygin gas (MCG) scalar field models in a nonflat universe. The potential and dynamics for these scalar field models, which describe the accelerated expansion of the universe, are reconstructed. According to the evolutionary behavior of the new HDE model, we derive the same form of dynamics and potential for the different SCG, GCG and MCG models. We also calculate the squared sound speed of the new HDE model as well as the SCG, GCG and MCG models, and investigate the new HDE Chaplygin gas models from the viewpoint of linear perturbation theory. In addition, all results in the nonflat universe are discussed in the limiting case of the flat universe, i.e. k = 0.

scholarly journals Reconstructing f(R) gravity from a Chaplygin scalar field in de Sitter spacetimes

2018 ◽  
Vol 15 (02) ◽  
pp. 1850027 ◽  
Author(s):  
Heba Sami ◽  
Neo Namane ◽  
Joseph Ntahompagaze ◽  
Maye Elmardi ◽  
Amare Abebe
Keyword(s):  
General Relativity ◽  
Scalar Field ◽  
Field Model ◽  
Exact Formula ◽  
Chaplygin Gas ◽  
Reconstruction Technique ◽  
Field Potentials ◽  
De Sitter ◽  
Cosmological Expansion ◽  
Lagrangian Densities

We present a reconstruction technique for models of [Formula: see text] gravity from the Chaplygin scalar field in flat de Sitter spacetimes. Exploiting the equivalence between [Formula: see text] gravity and scalar–tensor (ST) theories, and treating the Chaplygin gas (CG) as a scalar field model in a universe without conventional matter forms, the Lagrangian densities for the [Formula: see text] action are derived. Exact [Formula: see text] models and corresponding scalar field potentials are obtained for asymptotically de Sitter spacetimes in early and late cosmological expansion histories. It is shown that the reconstructed [Formula: see text] models all have General Relativity (GR) as a limiting solution.

scholarly journals Light of Planck-2015 on Noncanonical Inflation

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Kh. Saaidi ◽  
A. Mohammadi ◽  
T. Golanbari
Keyword(s):  
Scalar Field ◽  
Observational Data ◽  
Power Law ◽  
Hubble Parameter ◽  
Field Model ◽  
Kinetic Term ◽  
Inflationary Scenario ◽  
Slow Roll ◽  
Power Law Function ◽  
Free Parameters

Slow-roll inflationary scenario is considered in noncanonical scalar field model supposing a power-law function for kinetic term and using two formalisms. In the first approach, the potential is picked out as a power-law function, that is, the most common approach in studying inflation. Hamilton-Jacobi approach is selected as the second formalism, so that the Hubble parameter is introduced as a function of scalar field instead of the potential. Employing the last observational data, the free parameters of the model are constrained, and the predicted form of the potential and attractor behavior of the model are studied in detail.

NEW AGEGRAPHIC CHAPLYGIN GAS MODEL WITH VISCOSITY

2011 ◽  
Vol 26 (10) ◽  
pp. 727-737 ◽  
Author(s):  
LEI WANG ◽  
YA-BO WU ◽  
LEI LI ◽  
YUAN GAO ◽  
JIAN GAO
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Chaplygin Gas ◽  
Generalized Chaplygin Gas ◽  
Agegraphic Dark Energy ◽  
New Agegraphic Dark Energy ◽  
Flat Universe ◽  
Special Case

In this paper, motivated by Ref. 31, we study the so-called new agegraphic Chaplygin gas model with viscosity. Concretely, we establish the correspondence between the interacting new agegraphic dark energy (NADE) and variable generalized Chaplygin gas (VGCG) models in non-flat universe on the basis of reviewing related contents for the NADE and VGCG models. Furthermore, we reconstruct the potential of the new agegraphic scalar field as well as the dynamics of the scalar field according to the evolution of the agegraphic dark energy. Finally, we generalize our study to the case of NADE with viscosity, which includes the case without viscosity (ν = 0) as a special case.

Reconstruction of warm Chaplygin gas inflationary models

2020 ◽  
Vol 35 (32) ◽  
pp. 2050268
Author(s):  
Abdul Jawad ◽  
Shamaila Rani ◽  
Kazuharu Bamba ◽  
Nadeem Azhar
Keyword(s):  
Spectral Index ◽  
Effective Potential ◽  
Chaplygin Gas ◽  
Index Formula ◽  
Curvature Perturbation ◽  
Warm Inflation ◽  
Scalar Spectral Index ◽  
Dissipative Coefficient ◽  
Inflationary Parameters ◽  
Friedmann Robertson Walker

By assuming the specific Chaplygin gas model, we study the reconstruction of warm inflation model with the help of tensor-to-scalar ratio [Formula: see text] and scalar spectral index [Formula: see text]. In this regard, we take flat Friedmann–Robertson–Walker (FRW) metric and discuss the general forms of dissipative coefficient [Formula: see text] as well as effective potential [Formula: see text] for two dissipative regimes i.e., the weak and strong. We use inflationary parameters such as slow-roll parameters, power spectrum of the curvature perturbation, tensor spectrum, spectral index, scalar-to-tensor ratio and Hubble parameter to find the generalized form of dissipative coefficient and effective potential. We discuss the results of dissipative coefficient and reconstructed potential in detail for the specific choice of tensor-to-scalar ratio [Formula: see text] and scalar spectral index [Formula: see text].

scholarly journals RASTALL COSMOLOGY

2012 ◽  
Vol 18 ◽  
pp. 67-76 ◽  
Author(s):  
JÚLIO C. FABRIS ◽  
OLIVER F. PIATTELLA ◽  
DAVI C. RODRIGUES ◽  
CARLOS E. M. BATISTA ◽  
MAHAMADOU H. DAOUDA
Keyword(s):  
Scalar Field ◽  
Observational Data ◽  
Canonical Form ◽  
Conservation Law ◽  
Chaplygin Gas ◽  
Cosmological Models ◽  
The Self ◽  
Generalized Chaplygin Gas ◽  
Field Representation ◽  
Theory Of Gravity

We review the difficulties of the generalized Chaplygin gas model to fit observational data, due to the tension between background and perturbative tests. We argue that such issues may be circumvented by means of a self-interacting scalar field representation of the model. However, this proposal seems to be successful only if the self-interacting scalar field has a non-canonical form. The latter can be implemented in Rastall's theory of gravity, which is based on a modification of the usual matter conservation law. We show that, besides its application to the generalized Chaplygin gas model, other cosmological models based on Rastall's theory have many interesting and unexpected new features.

scholarly journals Matter power spectrum for the generalized Chaplygin gas model: The Newtonian approach

2008 ◽  
Vol 78 (10) ◽  
Author(s):  
J. C. Fabris ◽  
S. V. B. Gonçalves ◽  
H. E. S. Velten ◽  
W. Zimdahl
Keyword(s):  
Power Spectrum ◽  
Chaplygin Gas ◽  
Generalized Chaplygin Gas ◽  
Matter Power Spectrum
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