scholarly journals On the spherically symmetric Einstein–Yang–Mills–Higgs equations in Bondi coordinates

2012 ◽  
Vol 468 (2146) ◽  
pp. 3191-3214 ◽  
Author(s):  
Calvin Tadmon ◽  
Sophonie Blaise Tchapnda
Keyword(s):  
Scalar Field ◽  
Interaction Potential ◽  
Global Solutions ◽  
Scalar Fields ◽  
The Self ◽  
Spherically Symmetric ◽  
Yang Mills ◽  
Local Charge

We revisit and generalize, to the Einstein–Yang–Mills–Higgs (EYMH) system, previous results of Christodoulou and Chae concerning global solutions for the Einstein-scalar field and the Einstein–Maxwell–Higgs (EMH) equations. The novelty of the present work is twofold. For one thing, the assumption on the self-interaction potential is improved. For another thing, explanation is furnished why the solutions obtained here and those proved by Chae for the EMH system decay more slowly than those established by Christodoulou in the case of self-gravitating scalar fields. Actually, this latter phenomenon stems from the non-vanishing local charge in EMH and EYMH models.

scholarly journals A Riccati equation based approach to isotropic scalar field cosmologies

2014 ◽  
Vol 23 (07) ◽  
pp. 1450063 ◽  
Author(s):  
Tiberiu Harko ◽  
Francisco S. N. Lobo ◽  
M. K. Mak
Keyword(s):  
Scalar Field ◽  
Evolution Equation ◽  
Interaction Potential ◽  
Arbitrary Function ◽  
Field Potential ◽  
Type Equation ◽  
Scalar Fields ◽  
Cosmological Models ◽  
Late Time ◽  
Field Equations

Gravitationally coupled scalar fields ϕ, distinguished by the choice of an effective self-interaction potential V(ϕ), simulating a temporarily nonvanishing cosmological term, can generate both inflation and late time acceleration. In scalar field cosmological models the evolution of the Hubble function is determined, in terms of the interaction potential, by a Riccati type equation. In the present work, we investigate scalar field cosmological models that can be obtained as solutions of the Riccati evolution equation for the Hubble function. Four exact integrability cases of the field equations are presented, representing classes of general solutions of the Riccati evolution equation. The solutions correspond to cosmological models in which the Hubble function is proportional to the scalar field potential plus a linearly decreasing function of time, models with the time variation of the scalar field potential proportional to the potential minus its square, models in which the potential is the sum of an arbitrary function and the square of the function integral, and models in which the potential is the sum of an arbitrary function and the derivative of its square root, respectively. The cosmological properties of all models are investigated in detail, and it is shown that they can describe the inflationary or the late accelerating phase in the evolution of the universe.

BRANS-DICKE COSMOLOGY WITH FERMIONS AND CHAMELEON MECHANISM

2012 ◽  
Vol 07 ◽  
pp. 174-183
Author(s):  
DAO-JUN LIU ◽  
BIN YANG ◽  
XING-HUA JIN
Keyword(s):  
Scalar Field ◽  
Interaction Potential ◽  
The Self ◽  
Accelerated Expansion ◽  
Late Time ◽  
Fermion Field ◽  
Chameleon Mechanism ◽  
Expansion Of The Universe ◽  
Stable Solutions ◽  
The Universe

We study the cosmological dynamics of Brans-Dicke theory in which there are fermions with a coupling to BD scalar field as well as a self-interaction potential. The conditions that there exists a solution which is stable and represents a late-time accelerated expansion of the universe are found. It is shown that the late-time acceleration depends completely on the self-interaction of the fermion field if our investigation is restricted to the theory with positive BD parameter ω. Provided a negative ω is allowed, there will be another two class of stable solutions describing late-time accelerated expansion of the universe. Besides, we find that chameleon mechanism will be possessed in our theory when a suitable self-interaction of fermion field is considered.

scholarly journals STATIC SPHERICALLY SYMMETRIC SCALAR FIELD SPACETIMES WITH C0 MATCHING

2011 ◽  
Vol 26 (17) ◽  
pp. 1281-1290 ◽  
Author(s):  
SWASTIK BHATTACHARYA ◽  
PANKAJ S. JOSHI
Keyword(s):  
Scalar Field ◽  
Naked Singularity ◽  
Scalar Fields ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Spherically Symmetric ◽  
Curvature Singularity ◽  
Einstein Theory ◽  
Full Class ◽  
Strong Curvature

All the classes of static massless scalar field models currently available in the Einstein theory of gravity necessarily contain a strong curvature naked singularity. We obtain here a family of solutions for static massless scalar fields coupled to gravity, which does not have any strong curvature singularity. This class of models contain a thin shell of singular matter, which has a physical interpretation. The central curvature singularity is, however, avoided which is common to all static massless scalar field spacetime models known so far. Our result thus points out that the full class of solutions in this case may contain non-singular models, which is an intriguing possibility.

scholarly journals SPHERICALLY SYMMETRIC MASSIVE SCALAR FIELDS IN GENERAL RELATIVITY

2010 ◽  
Vol 25 (07) ◽  
pp. 1429-1438 ◽  
Author(s):  
MOHAMMAD MEHRPOOYA ◽  
D. MOMENI
Keyword(s):  
Scalar Field ◽  
Cosmological Constant ◽  
Scalar Fields ◽  
Matter Field ◽  
Massless Scalar ◽  
Special Choice ◽  
Spherically Symmetric ◽  
Elementary Functions ◽  
Field Equations ◽  
Tidal Forces

First, we review some attempts made to find the exact spherically symmetric solutions to Einstein field equations in the presence of scalar fields. Wyman's solution in both the static and the nonstatic scalar field is discussed, and it is shown why in the case of the nonstatic homogenous matter field the static metric cannot be represented in terms of elementary functions. We mention here that if the space–time is static, according to field equations, there are two options for fixing the scalar field: static (time-independent) and nonstatic (time-dependent). All these solutions are limited to the minimally coupled massless scalar fields and also in the absence of the cosmological constant. Then we show that if we are interested to have homogenous isotropic scalar field matter, we can construct a series solution in terms of the scalar field's mass and cosmological constant. This solution is static and possesses a locally flat case as a special choice of the mass of the scalar field and can be interpreted as an effective vacuum. Therefore, the mass of the scalar field eliminates any locally gravitational effect as tidal forces. Finally, we describe why this system is unstable in the language of dynamical systems.

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 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 SELF-DUAL VORTICES IN THE ABELIAN CHERN–SIMONS MODEL WITH TWO COMPLEX SCALAR FIELDS

2008 ◽  
Vol 23 (26) ◽  
pp. 2189-2198 ◽  
Author(s):  
YI-SHI DUAN ◽  
LI-DA ZHANG ◽  
YU-XIAO LIU
Keyword(s):  
Angular Momentum ◽  
Scalar Field ◽  
Field Model ◽  
Current Method ◽  
Scalar Fields ◽  
The Self ◽  
Complex Scalar ◽  
Topological Current ◽  
Chern Simons ◽  
Topological Term

Making use of ϕ-mapping topological current method, we discuss the self-dual vortices in the Abelian Chern–Simons model with two complex scalar fields. For each scalar field, an exact nontrivial equation with a topological term which is missing in many references is derived analytically. The general angular momentum is obtained. The magnetic flux which relates the two scalar fields is calculated. Furthermore, we investigate the vortex evolution processes, and find that because of the presence of the vortex molecule, these evolution processes are more complicated than the vortex evolution processes in the corresponding single scalar field model.

scholarly journals Singularities in Static Spherically Symmetric Configurations of General Relativity with Strongly Nonlinear Scalar Fields

Galaxies ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 72
Author(s):  
Oleksandr Stashko ◽  
Valery I. Zhdanov
Keyword(s):  
Scalar Field ◽  
Asymptotic Properties ◽  
Field Potential ◽  
Scalar Fields ◽  
Einstein Equations ◽  
Large Field ◽  
Spherically Symmetric ◽  
Schwarzschild Solution ◽  
Naked Singularities ◽  
Strongly Nonlinear

There are a number of publications on relativistic objects dealing either with black holes or naked singularities in the center. Here we show that there exist static spherically symmetric solutions of Einstein equations with a strongly nonlinear scalar field, which allow the appearance of singularities of a new type (“spherical singularities”) outside the center of curvature coordinates. As the example, we consider a scalar field potential ∼sinh(ϕ2n),n>2, which grows rapidly for large field values. The space-time is assumed to be asymptotically flat. We fulfill a numerical investigation of solutions with different n for different parameters, which define asymptotic properties at spatial infinity. Depending on the configuration parameters, we show that the distribution of the stable circular orbits of test bodies around the configuration is either similar to that in the case of the Schwarzschild solution (thus mimicking an ordinary black hole), or it contains additional rings of unstable orbits.

scholarly journals Gravitating Bubbles of Gluon Plasma above Deconfinement Temperature

Symmetry ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 1668
Author(s):  
Yves Brihaye ◽  
Fabien Buisseret
Keyword(s):  
Scalar Field ◽  
Equation Of State ◽  
Gluon Plasma ◽  
Einstein Gravity ◽  
Spherically Symmetric ◽  
Boson Stars ◽  
Complex Scalar ◽  
Symmetric Potential ◽  
Yang Mills ◽  
Complex Scalar Field

The equation of state of SU(3) Yang–Mills theory can be modelled by an effective Z3−symmetric potential depending on the temperature and on a complex scalar field ϕ. Allowing ϕ to be dynamical opens the way to the study of spatially localized classical configurations of the scalar field. We first show that spherically symmetric static Q-balls exist in the range (1−1.21)×Tc, Tc being the deconfinement temperature. Then we argue that Q-holes solutions, if any, are unphysical within our framework. Finally, we couple our matter Lagrangian to Einstein gravity and show that spherically symmetric static boson stars exist in the same range of temperature. The Q-ball and boson-star solutions we find can be interpreted as “bubbles” of deconfined gluonic matter; their mean radius is always smaller than 10 fm.

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