Scalar particles mass spectrum and localization on FRW branes embedded in a 5D de Sitter bulk

Open Physics ◽  
2014 ◽  
Vol 12 (7) ◽  
Author(s):  
Marina-Aura Dariescu ◽  
Ciprian Dariescu
Keyword(s):  
Scalar Field ◽  
Extra Dimension ◽  
Mass Parameter ◽  
Cosmic Time ◽  
Scalar Fields ◽  
Einstein Equations ◽  
Warp Factor ◽  
De Sitter ◽  
Massive Scalar Field ◽  
Scalar Particles

AbstractIn this paper, we study the scalar fields evolving on a FRW brane embedded in a five-dimensional de Sitter bulk. The scale function and the warp factor, solutions of the Einstein equations, are employed in the five-dimensional Gordon equation describing the massive scalar field, whose wave function depends on the cosmic time and on the extra-dimension. We point out the existence of bounded states and find a minimum value of the effective four-dimensional mass. For the test (scalar) field envelope along the extra-dimension, we derive the corresponding Schrödinger-like equation which is formally that for the Pöschl-Teller potential. Accordingly, we have obtained the quantization law for the mass parameter of the tested scalar field.

Some interactions of spherically symmetric massive scalar field with Brans–Dicke scalar field in Robertson–Walker universe

2019 ◽  
Vol 16 (04) ◽  
pp. 1950066 ◽  
Author(s):  
Kangujam Priyokumar Singh ◽  
Rajshekhar Roy Baruah
Keyword(s):  
Scalar Field ◽  
Cosmic Time ◽  
Scalar Fields ◽  
Cosmological Term ◽  
Physical Parameters ◽  
Spherically Symmetric ◽  
Massive Scalar ◽  
Field Equations ◽  
Massive Scalar Field ◽  
The Universe

Here in this work, we investigated the possible cosmological consequences of the interaction of Brans–Dicke scalar field and massive scalar field by considering spherically symmetric Robertson–Walker metric. The present problem can also be treated as an extension work of [K. Priyokumar et al., Interaction of gravitational field and Brans–Dicke field, Res. Astron. Astrophys. 16(4) (2016) 64; K. Priyokumar and M. Dewri, Interaction of electromagnetic field and Brans–Dicke field, Chinease J. Phys. 54 (2016) 845]. The exact solutions of the field equations are obtained with seven different cases. The behavior of the model and their contribution to the process of the evolution are examined in detail from some explicit and reasonable values of free parameter. We also presented the variations of certain physical parameters versus cosmic time graphically to compare our solutions with the present observational findings. When we studied further, it is found that the cosmological term [Formula: see text] takes a great role in the accelerating expansion of our universe when both scalar fields are exponentially increasing functions of time, while the cosmological term will not appear in the case when both the scalar fields are exponentially decreasing functions of time. Also, the scalar field is seen to have a tendency to increase the expansion of the universe, thereby flattening the universe.

scholarly journals The Effect of de-Sitter Like Background on Increasing the Zero Point Budget of Dark Energy

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Haidar Sheikhahmadi ◽  
Ali Aghamohammadi ◽  
Khaled Saaidi
Keyword(s):  
Scalar Field ◽  
Energy Density ◽  
Quantum Fluctuations ◽  
Zero Point ◽  
Scalar Fields ◽  
Massless Scalar Field ◽  
De Sitter ◽  
Data Set ◽  
Massive Scalar Field ◽  
The Universe

During this work, using subtraction renormalization mechanism, zero point quantum fluctuations for bosonic scalar fields in a de-Sitter like background are investigated. By virtue of the observed value for spectral index,ns(k), for massive scalar field the best value for the first slow roll parameter,ϵ, is achieved. In addition, the energy density of vacuum quantum fluctuations for massless scalar field is obtained. The effects of these fluctuations on other components of the universe are studied. By solving the conservation equation, for some different examples, the energy density for different components of the universe is obtained. In the case which all components of the universe are in an interaction, the different dissipation functions,Q~i, are considered. The time evolution ofρDE(z)/ρcri(z)shows thatQ~=3γH(t)ρmhas the best agreement in comparison to observational data including CMB, BAO, and SNeIa data set.

scholarly journals Spherically Symmetric Configurations in General Relativity in the Presence of a Linear Massive Scalar Field: Separation of a Distribution of Test Body Circular Orbits

2019 ◽  
Vol 64 (3) ◽  
pp. 189 ◽  
Author(s):  
O. S. Stashko ◽  
V. I. Zhdanov
Keyword(s):  
General Relativity ◽  
Scalar Field ◽  
Scalar Fields ◽  
Test Body ◽  
Einstein Equations ◽  
Strength Parameter ◽  
Spherically Symmetric ◽  
Massive Scalar ◽  
Circular Orbits ◽  
Massive Scalar Field

We study static spherically symmetric configurations in the presence of linear massive scalar fields within General Relativity. Static solutions of the Einstein equations are considered under conditions of asymptotic flatness. Each solution is fixed by the configuration mass and the field strength parameter, which are defined at spatial infinity. The metric coefficients and the scalar field for a specific configuration are obtained numerically. Then we study the time-like geodesics describing the test particle motion. The focus is on the distribution of stable circular orbits (SCOs) of the test particles around a configuration. We found that, for the continuum of configuration parameters, there exist two unlinked regions of SCOs that are separated by some annular region, where SCOs do not exist.

scholarly journals Quasinormal modes and their anomalous behavior for black holes in f(R) gravity

2021 ◽  
Vol 81 (5) ◽  
Author(s):  
Almendra Aragón ◽  
P. A. González ◽  
Eleftherios Papantonopoulos ◽  
Yerko Vásquez
Keyword(s):  
Black Hole ◽  
Scalar Field ◽  
Critical Mass ◽  
Quasinormal Modes ◽  
Scalar Fields ◽  
Critical Value ◽  
Anomalous Behavior ◽  
Modified Theories Of Gravity ◽  
De Sitter ◽  
Massive Scalar Field

AbstractWe study the propagation of scalar fields in the background of an asymptotically de Sitter black hole solution in f(R) gravity. The aim of this work is to analyze in modified theories of gravity the existence of an anomalous decay rate of the quasinormal modes (QNMs) of a massive scalar field which was recently reported in Schwarzschild black hole backgrounds, in which the longest-lived modes are the ones with higher angular number, for a scalar field mass smaller than a critical value, while that beyond this value the behavior is inverted. We study the QNMs for various overtone numbers and they depend on a parameter $$\beta $$ β which appears in the metric and characterizes the f(R) gravity. For small $$\beta $$ β , i.e. small deviations from the Schwarzschild–dS black hole the anomalous behavior in the QNMs is present for the photon sphere modes, and the critical value of the mass of the scalar field depends on the parameter $$\beta $$ β while for large $$\beta $$ β , i.e. large deviations, the anomalous behavior and the critical mass does not appear. Also, the critical mass of the scalar field increases when the overtone number increases until the f(R) gravity parameter $$\beta $$ β approaches the near extremal limit at which the critical mass of the scalar field does not depend anymore on the overtone number. The imaginary part of the quasinormal frequencies is always negative leading to a stable propagation of the scalar fields in this background.

scholarly journals SCALAR FIELD IN A MINIMALLY COUPLED BRANE WORLD: NO-HAIR AND OTHER NO-GO THEOREMS

2004 ◽  
Vol 13 (04) ◽  
pp. 593-606 ◽  
Author(s):  
K. A. BRONNIKOV ◽  
S. B. FADEEV ◽  
A. V. MICHTCHENKO
Keyword(s):  
Scalar Field ◽  
Strong Field ◽  
Scalar Fields ◽  
Brane World ◽  
Einstein Equations ◽  
De Sitter ◽  
Brane Worlds ◽  
Traversable Wormholes ◽  
Tensor Formula ◽  
Causal Structures

In the brane-world framework, we consider static, spherically symmetric configurations of a scalar field with the Lagrangian (∂ϕ)2/2-V(ϕ), confined on the brane. We use the 4D Einstein equations on the brane obtained by Shiromizu et al., containing the conventional stress tensor [Formula: see text], the tensor [Formula: see text] which is quadratic in [Formula: see text], and [Formula: see text] describing interaction with the bulk. For models under study, the tensor [Formula: see text] has zero divergence, allowing one to consider [Formula: see text]. Such a brane, whose 4D gravity is decoupled from the bulk geometry, may be called minimally coupled. Assuming [Formula: see text], we try to extend to brane worlds some theorems valid for scalar fields in general relativity (GR). Thus, the list of possible global causal structures in all models under consideration is shown to be the same as is known for vacuum with a cosmological constant in GR: Minkowski, Schwarzschild, (anti-) de Sitter and Schwarzschild–(anti-)de Sitter. A no-hair theorem, saying that, given a potential V≥0, asymptotically flat black holes cannot have nontrivial external scalar fields, is proved under certain restrictions. Some objects, forbidden in GR, are allowed on the brane, e.g, traversable wormholes supported by a scalar field, but only at the expense of enormous matter densities in the strong field region.

Noncommutative scalar field in de Sitter space–time and pair creation process

2021 ◽  
Vol 36 (02) ◽  
pp. 2150011
Author(s):  
Nabil Mehdaoui ◽  
Lamine Khodja ◽  
Salah Haouat
Keyword(s):  
Scalar Field ◽  
Chemical Potential ◽  
De Sitter Space ◽  
Space Time ◽  
Pair Creation ◽  
De Sitter ◽  
Creation Process ◽  
Scalar Particles ◽  
Constant Electromagnetic Field

In this work, we address the process of pair creation of scalar particles in [Formula: see text] de Sitter space–time in presence of a constant electromagnetic field by applying the noncommutativity on the scalar field up to first-order in [Formula: see text]. We calculate the density of particles created in the vacuum by the mean of the Bogoliubov transformations. In contrast to a previous result, we show that noncommutativity contributes to the pair creation process. We find that the noncommutativity plays the same role of chemical potential and gives an important interest for studies at high energies.

The backreaction of massive scalar field on FLRW and de Sitter spaces

2020 ◽  
Vol 17 (03) ◽  
pp. 2050033
Author(s):  
M. R. Setare ◽  
M. Sahraee
Keyword(s):  
Scalar Field ◽  
Energy Momentum Tensor ◽  
Friedmann Equation ◽  
Vacuum Expectation ◽  
Momentum Tensor ◽  
Scale Factor ◽  
Massive Scalar ◽  
De Sitter ◽  
Massive Scalar Field ◽  
Quantum Energy

In this paper, we obtain the effect of backreaction on the scale factor of the Friedmann–Lemaître–Robertson–Walker (FLRW) and de Sitter spaces. We consider a non-minimally coupled massive scalar field to the curvature scalar. For our purpose, we use the results of vacuum expectation values of energy–momentum tensor, which have been obtained previously. By substituting the quantum energy density into the Friedmann equation, we obtain the linear order perturbation of the scale factor. So, the effect of backreaction leads to the new scale factor.

scholarly journals Strong cosmic censorship under quasinormal modes of non-minimally coupled massive scalar field

2019 ◽  
Vol 79 (9) ◽  
Author(s):  
Bogeun Gwak
Keyword(s):  
Black Holes ◽  
Scalar Field ◽  
Decay Rate ◽  
Small Mass ◽  
Cosmic Censorship ◽  
Massive Scalar ◽  
De Sitter ◽  
Massive Scalar Field ◽  
Strong Cosmic Censorship ◽  
Cosmic Censorship Conjecture

Abstract We investigate the strong cosmic censorship conjecture in lukewarm Reissner–Nordström–de Sitter black holes (and Martínez–Troncoso–Zanelli black holes) using the quasinormal resonance of non-minimally coupled massive scalar field. The strong cosmic censorship conjecture is closely related to the stability of the Cauchy horizon governed by the decay rate of the dominant quasinormal mode. Here, dominant modes are obtained in the limits of small and large mass black holes. Then, we connect the modes by using the WKB approximation. In our analysis, the strong cosmic censorship conjecture is valid except in the range of the small-mass limit, in which the dominant mode can be assumed to be that of the de Sitter spacetime. Particularly, the coupling constant and mass of the scalar field determine the decay rate in the small mass range. Therefore, the validity of the strong cosmic censorship conjecture depends on the characteristics of the scalar field.

DE SITTER-SCHWARZSCHILD BLACK HOLE: ITS PARTICLELIKE CORE AND THERMODYNAMICAL PROPERTIES

1996 ◽  
Vol 05 (05) ◽  
pp. 529-540 ◽  
Author(s):  
I.G. DYMNIKOVA
Keyword(s):  
Black Hole ◽  
Lower Limit ◽  
Mass Parameter ◽  
Hawking Temperature ◽  
Einstein Equations ◽  
Black Hole Mass ◽  
De Sitter ◽  
Schwarzschild Black Hole ◽  
Schwarzschild Solution ◽  
Second Order Phase Transition

We analyze the globally regular solution of the Einstein equations describing a black hole whose singularity is replaced by the de Sitter core. The de Sitter—Schwarzschild black hole (SSBH) has two horizons. Inside of it there exists a particlelike structure hidden under the external horizon. The critical value of mass parameter M cr1 exists corresponding to the degenerate horizon. It represents the lower limit for a black-hole mass. Below M cr1 there is no black hole, and the de Sitter-Schwarzschild solution describes a recovered particlelike structure. We calculate the Hawking temperature of SSBH and show that specific heat is broken and changes its sign at the value of mass M cr 2>M cr 1 which means that a second-order phase transition occurs at that point. We show that the Hawking temperature drops to zero when a mass approaches the lower limit M cr1 .

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