scholarly journals Asymptotic behavior of a scalar field with an arbitrary potential trapped on a Randall-Sundrum’s braneworld: the effect of a negative dark radiation term on a Bianchi I brane

2013 ◽  
Vol 349 (1) ◽  
pp. 575-602 ◽  
Author(s):  
Dagoberto Escobar ◽  
Carlos R. Fadragas ◽  
Genly Leon ◽  
Yoelsy Leyva
Keyword(s):  
Asymptotic Behavior ◽  
Scalar Field ◽  
Dark Radiation ◽  
Bianchi I ◽  
Arbitrary Potential

scholarly journals Averaging generalized scalar field cosmologies II: locally rotationally symmetric Bianchi I and flat Friedmann–Lemaître–Robertson–Walker models

2021 ◽  
Vol 81 (6) ◽  
Author(s):  
Genly Leon ◽  
Sebastián Cuéllar ◽  
Esteban González ◽  
Samuel Lepe ◽  
Claudio Michea ◽  
...  
Keyword(s):  
Scalar Field ◽  
Nonlinear Dynamical Systems ◽  
Perturbation Parameter ◽  
Time Dependent ◽  
Late Time ◽  
De Sitter ◽  
Time Dynamics ◽  
Locally Rotationally Symmetric ◽  
Bianchi I ◽  
Rotationally Symmetric

AbstractScalar field cosmologies with a generalized harmonic potential and a matter fluid with a barotropic equation of state (EoS) with barotropic index $$\gamma $$ γ for the locally rotationally symmetric (LRS) Bianchi I and flat Friedmann–Lemaître–Robertson–Walker (FLRW) metrics are investigated. Methods from the theory of averaging of nonlinear dynamical systems are used to prove that time-dependent systems and their corresponding time-averaged versions have the same late-time dynamics. Therefore, the simplest time-averaged system determines the future asymptotic behavior. Depending on the values of $$\gamma $$ γ , the late-time attractors of physical interests are flat quintessence dominated FLRW universe and Einstein-de Sitter solution. With this approach, the oscillations entering the system through the Klein–Gordon (KG) equation can be controlled and smoothed out as the Hubble parameter H – acting as time-dependent perturbation parameter – tends monotonically to zero. Numerical simulations are presented as evidence of such behavior.

scholarly journals Quantization of Einstein-aether scalar field cosmology

2021 ◽  
Vol 81 (2) ◽  
Author(s):  
N. Dimakis ◽  
T. Pailas ◽  
A. Paliathanasis ◽  
G. Leon ◽  
Petros A. Terzis ◽  
...  
Keyword(s):  
Scalar Field ◽  
Classical Solution ◽  
Potential Function ◽  
Scalar Fields ◽  
Inflationary Model ◽  
Cosmological Theory ◽  
Local Functions ◽  
Arbitrary Potential ◽  
Scalar Field Cosmology ◽  
First Time

AbstractWe present, for the first time, the quantization process for the Einstein-aether scalar field cosmology. We consider a cosmological theory proposed as a Lorentz violating inflationary model, where the aether and scalar fields interact through the assumption that the aether action constants are ultra-local functions of the scalar field. For this specific theory there is a valid minisuperspace description which we use to quantize. For a particular relation between the two free functions entering the reduced Lagrangian the solution to the Wheeler–DeWitt equation as also the generic classical solution are presented for any given arbitrary potential function.

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.

scholarly journals Scalar Field in the Bianchi I: Noncommutative Classical and Quantum Cosmology

2009 ◽  
Vol 48 (12) ◽  
pp. 3567-3585 ◽  
Author(s):  
J. Socorro ◽  
Luis O. Pimentel ◽  
C. Ortiz ◽  
M. Aguero
Keyword(s):  
Scalar Field ◽  
Quantum Cosmology ◽  
Bianchi I

scholarly journals DYNAMICS OF MAGNETIZED BULK VISCOUS STRINGS IN BRANS–DICKE GRAVITY

2012 ◽  
Vol 21 (06) ◽  
pp. 1250055 ◽  
Author(s):  
MUHAMMAD SHARIF ◽  
SAIRA WAHEED
Keyword(s):  
Scalar Field ◽  
Power Law ◽  
Universe Model ◽  
Expanding Universe ◽  
Locally Rotationally Symmetric ◽  
Bianchi I ◽  
Rotationally Symmetric ◽  
Bulk Viscous ◽  
Proportionality Relationship

We explore locally rotationally symmetric Bianchi I universe in Brans–Dicke gravity with self-interacting potential by using charged viscous cosmological string fluid. We use a relationship between the shear and expansion scalars and also take the power law for scalar field as well as self-interacting potential. It is found that the resulting universe model maintains its anisotropic nature at all times due to the proportionality relationship between expansion and shear scalars. The physical implications of this model are discussed by using different parameters and their graphs. We conclude that this model corresponds to an accelerated expanding universe for particular values of the parameters.

scholarly journals Rotating cylindrical wormholes and energy conditions

2016 ◽  
Vol 31 (02n03) ◽  
pp. 1641022 ◽  
Author(s):  
K. A. Bronnikov ◽  
V. G. Krechet
Keyword(s):  
Scalar Field ◽  
Energy Condition ◽  
Flat Space ◽  
Null Energy Condition ◽  
Energy Conditions ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Throat Region ◽  
Cylindrically Symmetric ◽  
Arbitrary Potential

We seek wormholes among rotating cylindrically symmetric configurations in general relativity. Exact wormhole solutions are presented with such sources of gravity as a massless scalar field, a cosmological constant, and a scalar field with an exponential potential. However, none of these solutions are asymptotically flat, which excludes the existence of wormhole entrances as local objects in our Universe. To overcome this difficulty, we try to build configurations with flat asymptotic regions using the cut-and-paste procedure: on both sides of the throat, a wormhole solution is matched to a properly chosen region of flat space-time at some surfaces [Formula: see text] and [Formula: see text]. It is shown, however, that if the source of gravity in the throat region is a scalar field with an arbitrary potential, then one or both thin shells appearing on [Formula: see text] and [Formula: see text] inevitably violate the null energy condition. Thus, although rotating wormhole solutions are easily found without exotic matter, such matter is still necessary for obtaining asymptotic flatness.

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