scholarly journals Real scalar field, the nonrelativistic limit, and the cosmological expansion

2020 ◽  
Vol 102 (3) ◽  
Author(s):  
Lars H. Heyen ◽  
Stefan Floerchinger
Keyword(s):  
Scalar Field ◽  
Nonrelativistic Limit ◽  
Real Scalar ◽  
Cosmological Expansion

scholarly journals ON THE NONRELATIVISTIC LIMIT OF THE φ4 THEORY IN 2+1 DIMENSIONS

1996 ◽  
Vol 11 (36) ◽  
pp. 2825-2836 ◽  
Author(s):  
M. GOMES ◽  
J.M.C. MALBOUISSON ◽  
A.J. DA SILVA
Keyword(s):  
Quantum Theory ◽  
Scalar Field ◽  
Scattering Amplitude ◽  
Nonrelativistic Limit ◽  
Low Energy ◽  
The Self ◽  
Energy Correction ◽  
Real Scalar ◽  
Self Energy

We study the nonrelativistic limit of the quantum theory of a real scalar field with quartic self-interaction. The two-body scattering amplitude is written in such way as to separate the contributions of high and low energy intermediary states. From this result and the two-loop computation of the self-energy correction, we determine an effective nonrelativistic action.

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.

Real scalar field solutions of the EKG equations including matter

2020 ◽  
pp. 2150009
Author(s):  
A. Cabo Montes de Oca ◽  
D. Suarez Fontanella
Keyword(s):  
Dark Matter ◽  
Gravitational Field ◽  
Scalar Field ◽  
Scalar Fields ◽  
Stationary Solutions ◽  
Field Interaction ◽  
Small Bodies ◽  
Real Scalar ◽  
Static Solutions ◽  
Klein Gordon

Static (not stationary) solutions of the Einstein–Klein–Gordon (EKG) equations including matter are obtained for real scalar fields. The scalar field interaction with matter is considered. The introduced coupling allows the existence of static solutions in contraposition with the case of the simpler EKG equations for real scalar fields and gravity. Surprisingly, when the considered matter is a photon-like gas, it turns out that the gravitational field intensity at large radial distances becomes nearly a constant, exerting an approximately fixed force to small bodies at any distance. The effect is clearly related with the massless character of the photon-like field. It is also argued that the gravitational field can generate a bounding attraction, that could avoid the unlimited increase in mass with the radius of the obtained here solution. This phenomenon, if verified, may furnish a possible mechanism for explaining how the increasing gravitational potential associated to dark matter, finally decays at large distances from the galaxies. A method for evaluating these photon bounding effects is just formulated in order to be further investigated.

scholarly journals Cosmic expansion driven by real scalar field for different forms of potential

2013 ◽  
Vol 350 (1) ◽  
pp. 381-384 ◽  
Author(s):  
Murli Manohar Verma ◽  
Shankar Dayal Pathak
Keyword(s):  
Scalar Field ◽  
Cosmic Expansion ◽  
Real Scalar

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.

GLOBAL EXISTENCE TO THE EINSTEIN-SCALAR FIELD SYSTEM ON THE ROBERTSON–WALKER SPACE-TIMES WITH HYPERBOLIC AND SPHERICAL SYMMETRIES

2010 ◽  
Vol 07 (01) ◽  
pp. 69-83
Author(s):  
NORBERT NOUTCHEGUEME ◽  
ALEXIS NANGUE
Keyword(s):  
Asymptotic Behavior ◽  
Scalar Field ◽  
Global Existence ◽  
Initial Velocity ◽  
Existence Of Solutions ◽  
Expansion Factor ◽  
Positive Cosmological Constant ◽  
Field System ◽  
Global Existence Of Solutions ◽  
Cosmological Expansion

Global existence of solutions is proved and asymptotic behavior is investigated, in the case of a positive cosmological constant and positive initial velocity of the cosmological expansion factor.

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