scholarly journals SIGNATURE CHANGE BY GUP

2013 ◽  
Vol 22 (05) ◽  
pp. 1350026 ◽  
Author(s):  
T. GHANEH ◽  
F. DARABI ◽  
H. MOTAVALLI
Keyword(s):  
Phase Space ◽  
Scalar Field ◽  
Cosmological Constant ◽  
Generalized Uncertainty Principle ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Massive Scalar ◽  
Good Correspondence ◽  
Massive Scalar Field ◽  
Frw Metric

We revisit the issue of continuous signature transition from Euclidean to Lorentzian metrics in a cosmological model described by Friedmann–Robertson–Walker (FRW) metric minimally coupled with a self-interacting massive scalar field. Then, using a noncommutative (NC) phase space of dynamical variables deformed by generalized uncertainty principle (GUP), we show that the signature transition occurs even for a model described by the FRW metric minimally coupled with a free massless scalar field accompanied by a cosmological constant. This indicates that the continuous signature transition might have been easily occurred at early universe just by a free massless scalar field, a cosmological constant and a NC phase space deformed by GUP, without resorting to a massive scalar field having an ad hoc complicate potential. We also study the quantum cosmology of the model and obtain a solution of Wheeler–DeWitt (WD) equation which shows a good correspondence with the classical path.

scholarly journals Radiative correction to the Casimir energy for massive scalar field on a spherical surface

2017 ◽  
Vol 32 (24) ◽  
pp. 1750128 ◽  
Author(s):  
M. A. Valuyan
Keyword(s):  
Scalar Field ◽  
Radiative Correction ◽  
Spherical Surface ◽  
Perturbation Expansion ◽  
Casimir Energy ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Massive Scalar ◽  
Massive Scalar Field ◽  
Free Theory

In this paper, the first-order radiative correction to the Casimir energy for a massive scalar field in the [Formula: see text] theory on a spherical surface with [Formula: see text] topology was calculated. In common methods for calculating the radiative correction to the Casimir energy, the counter-terms related to free theory are used. However, in this study, by using a systematic perturbation expansion, the obtained counter-terms in renormalization program were automatically position-dependent. We maintained that this dependency was permitted, reflecting the effects of the boundary conditions imposed or background space in the problem. Additionally, along with the renormalization program, a supplementary regularization technique that we named Box Subtraction Scheme (BSS) was performed. This scheme presents a useful method for the regularization of divergences, providing a situation that the infinities would be removed spontaneously without any ambiguity. Analysis of the necessary limits of the obtained results for the Casimir energy of the massive and massless scalar field confirmed the appropriate and reasonable consistency of the answers.

scholarly journals Massive scalar field quasinormal modes of a Schwarzschild black hole surrounded by quintessence

Open Physics ◽  
2008 ◽  
Vol 6 (2) ◽  
Author(s):  
Chunrui Ma ◽  
Yuanxing Gui ◽  
Wei Wang ◽  
Fujun Wang
Keyword(s):  
Black Hole ◽  
Scalar Field ◽  
Quasinormal Modes ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Massive Scalar ◽  
Schwarzschild Black Hole ◽  
Third Order ◽  
Massive Scalar Field ◽  
Absolute Value

AbstractWe present the quasinormal frequencies of the massive scalar field in the background of a Schwarzchild black hole surrounded by quintessence with the third-order WKB method. The mass of the scalar field u plays an important role in studying the quasinormal frequencies, the real part of the frequencies increases linearly as mass of the field u increases, while the imaginary part in absolute value decreases linearly which leads to damping more slowly than the massless scalar field. The frequencies have a limited value, so it is easier to detect the quasinormal modes. Moreover, owing to the presence of the quintessence, the massive scalar field damps more slowly.

scholarly journals CASIMIR PISTONS FOR MASSIVE SCALAR FIELDS

2009 ◽  
Vol 24 (05) ◽  
pp. 393-400 ◽  
Author(s):  
XIANG-HUA ZHAI ◽  
YAN-YAN ZHANG ◽  
XIN-ZHOU LI
Keyword(s):  
Scalar Field ◽  
Casimir Force ◽  
Scalar Fields ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Two Dimensional ◽  
Massive Scalar ◽  
Regularization Technique ◽  
Massive Scalar Field ◽  
Physical Result

The Casimir force on two-dimensional pistons for massive scalar fields with both Dirichlet and hybrid boundary conditions is computed. The physical result is obtained by making use of generalized ζ-function regularization technique. The influence of the mass and the position of the piston in the force is studied graphically. The Casimir force for massive scalar field is compared to that for massless scalar field.

scholarly journals BORN–INFELD BLACK HOLES COUPLED TO A MASSIVE SCALAR FIELD

2011 ◽  
Vol 20 (13) ◽  
pp. 2471-2496 ◽  
Author(s):  
DANIELA A. GEORGIEVA ◽  
IVAN ZH. STEFANOV ◽  
STOYTCHO S. YAZADJIEV ◽  
MICHAIL D. TODOROV
Keyword(s):  
Black Holes ◽  
Scalar Field ◽  
Causal Structure ◽  
Analytical Techniques ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Massive Scalar ◽  
Massive Scalar Field ◽  
Theories Of Gravity ◽  
Extremal Black Holes

Born–Infeld black holes in the scalar–tensor theories of gravity with massless scalar field have been recently obtained [I. Stefanov, S. Yazadjiev and M. Todorov, Phys. Rev. D75 (2007) 084036; Mod. Phys. Lett. A.23(34) (2008) 2915; Class. Quantum Gravity26 (2009) 015006]. The aim of the current paper is to study the effect of the inclusion of a potential for the scalar field in the theory, through a combination of analytical techniques and numerical methods. The black holes coupled to a massive scalar field have richer causal structure in comparison to the massless scalar field case. In the former case, the black holes may have a second, inner horizon. The presence of potential for the scalar field allows the existence of extremal black holes for certain values of the mass of the scalar field and the magnetic (electric) charge of the black hole. The solutions are stable against spherically symmetric perturbations. Arguments in favor of the general stability of the solutions coming from the application of the "turning point" method are also presented.

FLAT COSMOLOGICAL MODELS WITH MASSIVE SCALAR FIELD IN GAUGE THEORIES OF GRAVITY

2003 ◽  
Vol 12 (08) ◽  
pp. 1487-1497 ◽  
Author(s):  
G. V. VERESHCHAGIN
Keyword(s):  
Scalar Field ◽  
Gauge Theories ◽  
Cosmological Models ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Massive Scalar ◽  
Effective Equation ◽  
Massive Scalar Field ◽  
Theories Of Gravity ◽  
Contraction Stage

Solutions of gravitational equations of gauge theories of gravity in homogeneous isotropic world with massive scalar field are investigated in the case of flat cosmological models. Special attention is dedicated to behavior of solutions on contraction stage. It is shown, that on expansion stage inflationary solutions are generic feature of the model. At the same time on contraction stage an effective equation of state can be similar to the case of massless scalar field p=ρ at the beginning of evolution and tends to the equation of ultrarelativistic gas p=ρ/3. The Hubble parameter tends to some negative value on contraction stage, depending on the mass of the scalar field. Nonsingular solutions in this model are unstable.

scholarly journals The Effect of a Positive Cosmological Constant on the Bounce of Loop Quantum Cosmology

Mathematics ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 186
Author(s):  
Mercedes Martín-Benito ◽  
Rita B. Neves
Keyword(s):  
Scalar Field ◽  
Cosmological Constant ◽  
Quantum Cosmology ◽  
Quantum Dynamics ◽  
Solvable Model ◽  
Massless Scalar ◽  
Loop Quantum Cosmology ◽  
Massless Scalar Field ◽  
Positive Cosmological Constant ◽  
Semiclassical States

We provide an analytical solution to the quantum dynamics of a flat Friedmann-Lemaître- Robertson-Walker model with a massless scalar field in the presence of a small and positive cosmological constant, in the context of Loop Quantum Cosmology. We use a perturbative treatment with respect to the model without a cosmological constant, which is exactly solvable. Our solution is approximate, but it is precisely valid at the high curvature regime where quantum gravity corrections are important. We compute explicitly the evolution of the expectation value of the volume. For semiclassical states characterized by a Gaussian spectral profile, the introduction of a positive cosmological constant displaces the bounce of the solvable model to lower volumes and to higher values of the scalar field. These displacements are state dependent, and in particular, they depend on the peak of the Gaussian profile, which measures the momentum of the scalar field. Moreover, for those semiclassical states, the bounce remains symmetric, as in the vanishing cosmological constant case. However, we show that the behavior of the volume is more intricate for generic states, leading in general to a non-symmetric bounce.

scholarly journals GRAVITATIONAL COLLAPSE OF MASSLESS SCALAR FIELD WITH NEGATIVE COSMOLOGICAL CONSTANT IN (2+1) DIMENSIONS

2006 ◽  
Vol 15 (04) ◽  
pp. 545-557 ◽  
Author(s):  
R. CHAN ◽  
M. F. A. DA SILVA ◽  
JAIME F. VILLAS DA ROCHA
Keyword(s):  
Black Holes ◽  
Scalar Field ◽  
Cosmological Constant ◽  
Gravitational Collapse ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Field Equations ◽  
Negative Cosmological Constant ◽  
Global Properties ◽  
Scalar Field Equations

The (2+1)-dimensional geodesic circularly symmetric solutions of Einstein-massless-scalar field equations with negative cosmological constant are found and their local and global properties are studied. It is found that one of them represents gravitational collapse where black holes are always formed.

scholarly journals TURBULENT INSTABILITY OF ANTI-DE SITTER SPACE–TIME

2013 ◽  
Vol 28 (22n23) ◽  
pp. 1340020 ◽  
Author(s):  
MACIEJ MALIBORSKI ◽  
ANDRZEJ ROSTWOROWSKI
Keyword(s):  
Scalar Field ◽  
Cosmological Constant ◽  
Numerical Study ◽  
De Sitter Space ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Spherically Symmetric ◽  
De Sitter ◽  
Field System ◽  
Technical Details

In these lecture notes, we discuss recently conjectured instability of anti-de Sitter space, resulting in gravitational collapse of a large class of arbitrarily small initial perturbations. We uncover the technical details used in the numerical study of spherically symmetric Einstein-massless scalar field system with negative cosmological constant that led to the conjectured instability.

scholarly journals Logarithmic corrections to the entropy of scalar field in BTZ black hole spacetime

2017 ◽  
Vol 26 (04) ◽  
pp. 1750038 ◽  
Author(s):  
Dharm Veer Singh ◽  
Shobhit Sachan
Keyword(s):  
Scalar Field ◽  
Entanglement Entropy ◽  
Mass Term ◽  
Conformal Anomaly ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Btz Black Hole ◽  
Logarithmic Divergence ◽  
Massive Scalar Field ◽  
Calculated Mass

The entanglement entropy correlates two quantum subsystems which are part of a larger system. A logarithmic divergence term present in the entanglement entropy is universal in nature and directly proportional to the conformal anomaly. We study this logarithmic divergence term of entropy for massive scalar field in [Formula: see text] dimensions by applying numerical techniques to entanglement entropy approach. This (2+1)-dimensional massive theory can be obtained from the (3+1)-dimensional massless scalar field via dimensional reduction. We also calculated mass corrections to entanglement entropy for scalar field. Finally, we observe that the area law contribution to the entanglement entropy is not affected by this mass term and the universal quantities depend upon the basic properties of the system.

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