scholarly journals WARM-POLYTROPIC INFLATIONARY UNIVERSE MODEL

2013 ◽  
Vol 22 (08) ◽  
pp. 1350041 ◽  
Author(s):  
M. R. SETARE ◽  
M. J. S. HOUNDJO ◽  
V. KAMALI
Keyword(s):  
Exact Solution ◽  
Scalar Field ◽  
Hubble Parameter ◽  
Inflationary Universe ◽  
Universe Model ◽  
Polytropic Gas ◽  
Slow Roll ◽  
Universe Models ◽  
Explicit Expressions

In this paper, we study warm inflationary universe models in the context of a polytropic gas. We derive the characteristics of this model in slow-roll approximation and develop our model in two cases: (1) for a constant dissipative parameter Γ; (2) Γ as a function of scalar field ϕ. In these cases, we will obtain exact solution for the scalar field and Hubble parameter. We will also obtain explicit expressions for the tensor-scalar ratio R, scalar spectrum index ns and its running αs in slow-roll approximation.

scholarly journals Exact and Slow-Roll Solutions for Exponential Power-Law Inflation Connected with Modified Gravity and Observational Constraints

Universe ◽  
2020 ◽  
Vol 6 (11) ◽  
pp. 199
Author(s):  
Igor Fomin ◽  
Sergey Chervon
Keyword(s):  
Scalar Field ◽  
Power Law ◽  
Hubble Parameter ◽  
Gravity Models ◽  
Observational Constraints ◽  
Slow Roll ◽  
Correct Model ◽  
Scalar Spectral Index ◽  
Wide Range ◽  
Exponential Power

We investigate the ability of the exponential power-law inflation to be a phenomenologically correct model of the early universe. We study General Relativity (GR) scalar cosmology equations in Ivanov–Salopek–Bond (or Hamilton–Jacobi like) representation where the Hubble parameter H is the function of a scalar field ϕ. Such approach admits calculation of the potential for given H(ϕ) and consequently reconstruction of f(R) gravity in parametric form. By this manner the Starobinsky potential and non-minimal Higgs potential (and consequently the corresponding f(R) gravity) were reconstructed using constraints on the model’s parameters. We also consider methods for generalising the obtained solutions to the case of chiral cosmological models and scalar-tensor gravity. Models based on the quadratic relationship between the Hubble parameter and the function of the non-minimal interaction of the scalar field and curvature are also considered. Comparison to observation (PLANCK 2018) data shows that all models under consideration give correct values for the scalar spectral index and tensor-to-scalar ratio under a wide range of exponential-power-law model’s parameters.

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.

scholarly journals Tachyon-polytropic inflation on the brane

Open Physics ◽  
2013 ◽  
Vol 11 (5) ◽  
Author(s):  
Mohammad Setare ◽  
Vahid Kamali
Keyword(s):  
Equation Of State ◽  
Cosmological Parameters ◽  
High Energy ◽  
Wilkinson Microwave Anisotropy Probe ◽  
Inflationary Universe ◽  
Universe Model ◽  
Exponential Potential ◽  
Energy Limit ◽  
High Energy Limit ◽  
Slow Roll

AbstractWe consider the tachyon-brane inflationary universe model in the context of a polytropic gas equation of state. In slow-roll approximation, we discuss general conditions of this model. For exponential potential, in high-energy limit the characteristics of the model are presented. By using the seven-year Wilkinson Microwave Anisotropy Probe (WMAP7) observational data, we constrain the cosmological parameters of the model.

CLASSICAL PERTURBATIONS FROM DECOHERENCE OF QUANTUM FLUCTUATIONS IN THE INFLATIONARY UNIVERSE

1990 ◽  
Vol 05 (28) ◽  
pp. 2311-2317 ◽  
Author(s):  
ROBERT BRANDENBERGER ◽  
RAYMOND LAFLAMME ◽  
MILAN MIJIĆ
Keyword(s):  
Scalar Field ◽  
Coherence Length ◽  
Quantum Fluctuations ◽  
Inflationary Universe ◽  
De Sitter ◽  
Density Perturbations ◽  
Hubble Radius ◽  
Universe Models

The evolution of a scalar field interacting with an environment in the de Sitter phase of an inflationary Universe is studied. The environment is taken to be a second scalar field. It is shown that the coherence length of the quantum fluctuations rapidly decreases after the wavelength of the perturbation crosses the Hubble radius. Hence, the fluctuations can be interpreted as classical. This lends support to the usual derivation of the spectrum of density perturbations in inflationary Universe models.

Inflationary dynamics in f(𝒢) gravity

2017 ◽  
Vol 26 (04) ◽  
pp. 1750030 ◽  
Author(s):  
M. Sharif ◽  
Ayesha Ikram
Keyword(s):  
Scalar Field ◽  
Equation Of State ◽  
Power Spectrum ◽  
Universe Model ◽  
De Sitter ◽  
Slow Roll ◽  
Homogeneous Universe ◽  
Text Model ◽  
Flow Functions ◽  
Hubble Flow

This paper investigates inflationary dynamics for isotropic and homogeneous universe model in the background of [Formula: see text] gravity. We construct Hubble-flow functions, slow-roll parameters, amplitude of scalar power spectrum, spectral index and tensor–scalar ratio for a particular form of equation of state which describes quasi-de Sitter expansion. The dynamics of inflationary epoch is analyzed for scalar field as well as fluid cosmology with viable power-law [Formula: see text] model. We obtain different potential functions that correspond to chaotic inflation and Starobinsky type models. The graphical behavior of these parameters shows compatible results with observational Planck 2015 data in this gravity.

scholarly journals Study of Homogeneous and Isotropic Universe in f(R,Tφ) Gravity

2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
M. Sharif ◽  
Aisha Siddiqa
Keyword(s):  
Scalar Field ◽  
Equation Of State ◽  
Deceleration Parameter ◽  
Hubble Parameter ◽  
State Parameter ◽  
Universe Model ◽  
Effective Equation ◽  
Isotropic Universe ◽  
First Order ◽  
Equation Of State Parameter

This paper is devoted to study the cosmological behavior of homogeneous and isotropic universe model in the context of f(R,Tφ) gravity, where φ is the scalar field. For this purpose, we follow the first-order formalism defined by H=W(φ). We evaluate Hubble parameter, effective equation of state parameter (ωeff), deceleration parameter, and potential of scalar field for three different values of W(φ). We obtain phantom era in some cases for the early times. It is found that exponential expression of W(φ) yields ωeff independent of time for flat universe and independent of model parameter otherwise. It is concluded that our model corresponds to ΛCDM for both initial and late times.

PARTICLE PRODUCTION DURING INFLATIONARY REHEATING

1992 ◽  
Vol 07 (09) ◽  
pp. 2033-2044 ◽  
Author(s):  
M. BASLER ◽  
B. KÄMPFER
Keyword(s):  
Scalar Field ◽  
Particle Production ◽  
Field Model ◽  
Particle Creation ◽  
Background Field ◽  
Time Development ◽  
Parameter Dependence ◽  
Inflationary Universe ◽  
Numerical Investigations ◽  
Universe Models

A possible reheating mechanism in inflationary universe models is studied in some detail. Results are presented of numerical investigations of particle creation and corresponding reheating within a self-coupled scalar field model. By using the method of Hamiltonian diagonalization attention is devoted to the time development of the process and its parameter dependence. The effect of particle production is found to depend strongly on the anharmonicity of the potential around its minimum and on the amplitude of the oscillations of the scalar background field.

Dynamics of single-field inflation in the framework of holographic f(T) gravity

2018 ◽  
Vol 15 (10) ◽  
pp. 1850167 ◽  
Author(s):  
Surajit Chattopadhyay ◽  
Antonio Pasqua ◽  
Irina Radinschi ◽  
Aroonkumar Beesham
Keyword(s):  
Dark Energy ◽  
Scalar Field ◽  
Energy Density ◽  
Linear Form ◽  
Index Formula ◽  
Inflationary Universe ◽  
Ricci Dark Energy ◽  
Slow Roll ◽  
Scalar Spectral Index ◽  
Single Field

In the work reported in the present paper, we have considered the inflationary dynamics inspired by holographic Ricci dark energy (HRDE) with the energy density [Formula: see text] in the framework of [Formula: see text] gravity. We have considered a [Formula: see text]-gravity model in linear form, which is sourced by a canonical scalar field due to the HRDE. We have investigated an inflationary Universe in this framework through slow-roll formalism. We also studied the scalar spectral index [Formula: see text] and tensor-to-scalar ratio [Formula: see text], which have come out to be in agreement with WMAP[Formula: see text]BAO[Formula: see text][Formula: see text] and Planck 2015 data.

scholarly journals CLOSED INFLATIONARY UNIVERSE MODELS IN BRANE WORLD COSMOLOGY

2005 ◽  
Vol 14 (05) ◽  
pp. 861-872 ◽  
Author(s):  
SERGIO DEL CAMPO ◽  
RAMÓN HERRERA ◽  
JOEL SAAVEDRA
Keyword(s):  
General Relativity ◽  
Scalar Field ◽  
Brane World ◽  
Inflationary Universe ◽  
Closed Universe ◽  
Cosmological Context ◽  
The One ◽  
Universe Models ◽  
Einstein’S General Relativity

In this article we study closed inflationary universe models proposed by Linde in a brane world cosmological context. In this scenario we determine and characterize the existence of a closed universe, in presence of one self-interacting scalar field with an inflationary stage. We have found that our model, which takes into account a Brane World Cosmology, is less restrictive than the one that uses standard Einstein's General Relativity cosmology.

LOGAMEDIATE INFLATION ON THE BRANE

2012 ◽  
Vol 27 (18) ◽  
pp. 1250101 ◽  
Author(s):  
RAMÓN HERRERA ◽  
MARCO OLIVARES
Keyword(s):  
Scalar Field ◽  
Energy Density ◽  
Observational Data ◽  
High Energy ◽  
Inflationary Universe ◽  
Universe Model ◽  
Tachyon Field ◽  
Energy Limit ◽  
High Energy Limit

Brane inflationary universe model in the context of logamediate inflation is studied. As the energy density we consider two different fields, first a standard scalar field, and then a tachyon field. In the high-energy limit we describes the conditions for theses models. The parameters of our models are constrained from the observational data.

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