Constraints on the scalar-field potential in inflationary models

1991 ◽  
Vol 43 (4) ◽  
pp. 965-976 ◽  
Author(s):  
Fred C. Adams ◽  
Katherine Freese ◽  
Alan H. Guth
Keyword(s):  
Scalar Field ◽  
Field Potential ◽  
Inflationary Models

Scalar field potential in inflationary models: Reconstruction and further constraints

1995 ◽  
Vol 51 (12) ◽  
pp. 6722-6735 ◽  
Author(s):  
Fred C. Adams ◽  
Katherine Freese
Keyword(s):  
Scalar Field ◽  
Field Potential ◽  
Inflationary Models

scholarly journals Gauss–Bonnet term corrections in scalar field cosmology

2020 ◽  
Vol 80 (12) ◽  
Author(s):  
Igor Fomin
Keyword(s):  
Scalar Field ◽  
Field Potential ◽  
Einstein Gravity ◽  
Minimal Coupling ◽  
Evolution Of The Universe ◽  
Scalar Field Cosmology ◽  
The Universe ◽  
Bonnet Term ◽  
Inflationary Models

AbstractThe influence of non-minimal coupling of a scalar field and the Gauss–Bonnet term on the inflationary stage of evolution of the universe is investigated in this paper. The main cosmological effects of such a coupling were considered. The deviations between Einstein–Gauss–Bonnet inflation and standard one based on Einstein gravity were determined. The corrections of a weak GB coupling preserving the type of the scalar field potential to standard inflationary models is considered as well.

scholarly journals CHAOTIC INFLATION ON THE RANDALL–SUNDRUM TWO-BRANE MODEL

2010 ◽  
Vol 25 (31) ◽  
pp. 2697-2713
Author(s):  
KOUROSH NOZARI ◽  
SIAMAK AKHSHABI
Keyword(s):  
Scalar Field ◽  
Field Potential ◽  
Friedmann Equation ◽  
Warp Factor ◽  
Model Parameters ◽  
Stabilization Mechanism ◽  
Brane Model ◽  
Inflation Model ◽  
Bulk Scalar Field ◽  
Chaotic Inflation

We construct an inflation model on the Randall–Sundrum I (RSI) brane where a bulk scalar field stabilizes the inter-brane separation. We study impact of the bulk scalar field on the inflationary dynamics on the brane. We proceed in two different approaches: in the first approach, the stabilizing field potential is directly appeared in the Friedmann equation and the resulting scenario is effectively a two-field inflation. In the second approach, the stabilization mechanism is considered in the context of a warp factor so that there is just one field present that plays the roles of both inflaton and stabilizer. We study constraints imposed on the model parameters from recent observations.

scholarly journals Dynamics of scalar potentials in theory of gravity

2019 ◽  
Vol 97 (8) ◽  
pp. 880-894
Author(s):  
M. Zubair ◽  
Farzana Kousar ◽  
Saira Waheed
Keyword(s):  
Scalar Field ◽  
Field Potential ◽  
Graphical Analysis ◽  
Chaplygin Gas ◽  
Field Potentials ◽  
De Sitter ◽  
Field Equations ◽  
Barotropic Fluid ◽  
First Case ◽  
De Sitter Universe

In this paper, we explore the nature of scalar field potential in [Formula: see text] gravity using a well-motivated reconstruction scheme for flat Friedmann–Robertson–Walker (FRW) geometry. The beauty of this scheme lies in the assumption that the Hubble parameter can be expressed in terms of scalar field and vice versa. Firstly, we develop field equations in this gravity and present some general explicit forms of scalar field potential via this technique. In the first case, we take the de Sitter universe model and construct some field potentials by taking different cases for the coupling function. In the second case, we derive some field potentials using the power law model in the presence of different matter sources like barotropic fluid, cosmological constant, and Chaplygin gas for some coupling functions. From graphical analysis, it is concluded that using some specific values of the involved parameters, the reconstructed scalar field potentials are cosmologically viable in both cases.

scholarly journals Isotropic exact solutions in $$F(R,Y,\phi )$$ gravity via Noether symmetries

2021 ◽  
Vol 81 (2) ◽  
Author(s):  
Saira Waheed ◽  
Iqra Nawazish ◽  
M. Zubair
Keyword(s):  
Scalar Field ◽  
Exact Solutions ◽  
Field Potential ◽  
Noether Symmetries ◽  
Dynamical Equations ◽  
Curvature Invariant ◽  
Gauge Symmetries ◽  
Cosmic Evolution ◽  
Fluid Matter ◽  
Alpha Beta

AbstractThe present article investigates the existence of Noether and Noether gauge symmetries of flat Friedman–Robertson–Walker universe model with perfect fluid matter ingredients in a generalized scalar field formulation namely $$f(R,Y,\phi )$$ f ( R , Y , ϕ ) gravity, where R is the Ricci scalar and Y denotes the curvature invariant term defined by $$Y=R_{\alpha \beta }R^{\alpha \beta }$$ Y = R α β R α β , while $$\phi $$ ϕ represents scalar field. For this purpose, we assume different general cases of generic $$f(R,Y,\phi )$$ f ( R , Y , ϕ ) function and explore its possible forms along with field potential $$V(\phi )$$ V ( ϕ ) by taking constant and variable coupling function of scalar field $$\omega (\phi )$$ ω ( ϕ ) . In each case, we find non-trivial symmetry generator and its related first integrals of motion (conserved quantities). It is seen that due to complexity of the resulting system of Lagrange dynamical equations, it is difficult to find exact cosmological solutions except for few simple cases. It is found that in each case, the existence of Noether symmetries leads to power law form of scalar field potential and different new types of generic function. For the acquired exact solutions, we discuss the cosmology generated by these solutions graphically and discuss their physical significance which favors the accelerated expanding eras of cosmic evolution.

scholarly journals PRE-INFLATION IN THE PRESENCE OF CONFORMAL COUPLING

2004 ◽  
Vol 19 (11) ◽  
pp. 807-816
Author(s):  
APOSTOLOS KUIROUKIDIS ◽  
DEMETRIOS B. PAPADOPOULOS
Keyword(s):  
Scalar Field ◽  
Exact Solutions ◽  
Hubble Parameter ◽  
Field Potential ◽  
Critical Value ◽  
Big Bang ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Conformal Parameter ◽  
Flrw Universe

We consider a massless scalar field, conformally coupled to the Ricci scalar curvature, in the pre-inflation era of a closed FLRW Universe. The scalar field potential can be of the form of the Coleman–Weinberg one-loop potential, which is flat at the origin and drives the inflationary evolution. For positive values of the conformal parameter ξ, less than the critical value ξ c =(1/6), the model admits exact solutions with nonzero minimum scale factor and zero initial Hubble parameter. Thus these solutions can be matched smoothly to the so-called Pre-Big-Bang models. At the end of this pre-inflation era one can match inflationary solutions by specifying the form of the potential and the whole solution is of the class C(1).

scholarly journals Inflationary limits on the size of compact extra space

2019 ◽  
Vol 28 (13) ◽  
pp. 1941004 ◽  
Author(s):  
V. V. Nikulin ◽  
Sergey G. Rubin
Keyword(s):  
Scalar Field ◽  
Planck Mass ◽  
Extra Space ◽  
Inflationary Models ◽  
Kaluza Klein

We study restrictions imposed on the parameters of the Kaluza–Klein extra space supplied by the standard inflationary models. It is shown that the size of the extra space cannot be larger than [Formula: see text][Formula: see text]cm and the [Formula: see text]-dimensional Planck mass should be larger than [Formula: see text][Formula: see text]GeV. The validity of these estimates is discussed. We also study creation of stable excitations of scalar field as the result of the extra metric evolution.

scholarly journals SPECTRA OF RELIC GRAVITONS AND BRANS–DICKE THEORY

2005 ◽  
Vol 20 (02) ◽  
pp. 127-134 ◽  
Author(s):  
B. K. SAHOO
Keyword(s):  
Scalar Field ◽  
Energy Density ◽  
Time Dependence ◽  
Gravitational Waves ◽  
Hubble Parameter ◽  
Frequency Dependent ◽  
Cosmological Expansion ◽  
Relic Gravitational Waves ◽  
Matter Energy ◽  
Inflationary Models

The spectra of relic gravitational waves produced as a result of cosmological expansion of the inflationary models are derived in Brans–Dicke (BD) theory of gravity. The time dependence of the very early Hubble parameter and matter energy density are derived from frequency-dependent spectrum of relic gravitational waves. Also it is found that Brans–Dicke scalar field contributes to the energy density of relic gravitons.

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