Cosmological solution with matter in a new theory of gravitation

1980 ◽  
Vol 58 (6) ◽  
pp. 729-736 ◽  
Author(s):  
G. Kunstatter ◽  
J. W. Moffat ◽  
P. Savaria
Keyword(s):  
Energy Density ◽  
Lower Bound ◽  
Initial Temperature ◽  
Cosmological Solution ◽  
Homogeneous Solution ◽  
Helium Abundance ◽  
Hermitian Metric ◽  
Plane Symmetric ◽  
Curvature Energy ◽  
Theory Of Gravitation

We present a plane-symmetric, homogeneous solution with matter in a theory of gravitation based on a non-symmetric Hermitian metric. The solution describes a universe which begins with finite 4-curvature, energy density, and temperature. The initial temperature [Formula: see text] depends on a new parameter κ in the theory. An analysis of primordial helium abundance gives rise to a lower bound [Formula: see text]. The resulting cosmology is consistent with all presently known observations.

scholarly journals Plane Symmetric Solutions of a Scalar-Tensor Theory of Gravitation

1977 ◽  
Vol 30 (1) ◽  
pp. 109 ◽  
Author(s):  
DRK Reddy
Keyword(s):  
General Relativity ◽  
Empty Space ◽  
Scalar Fields ◽  
Scalar Tensor Theory ◽  
Field Equations ◽  
Plane Symmetric ◽  
Zero Mass ◽  
Tensor Theory ◽  
Special Cases ◽  
Theory Of Gravitation

Plane symmetric solutions of a scalar-tensor theory proposed by Dunn have been obtained. These solutions are observed to be similar to the plane symmetric solutions of the field equations corresponding to zero mass scalar fields obtained by Patel. It is found that the empty space-times of general relativity discussed by Taub and by Bera are obtained as special cases.

scholarly journals f(T) gravity and energy distribution in Landau–Lifshitz prescription

2018 ◽  
Vol 27 (04) ◽  
pp. 1850039 ◽  
Author(s):  
M. G. Ganiou ◽  
M. J. S. Houndjo ◽  
J. Tossa
Keyword(s):  
General Relativity ◽  
Energy Density ◽  
Energy Distribution ◽  
Cosmic String ◽  
Mass Formula ◽  
Plane Symmetric ◽  
Symmetric Metrics ◽  
Teleparallel Theory ◽  
Momentum Complex ◽  
Theory View

We investigate in this paper the Landau–Lifshitz energy distribution in the framework of [Formula: see text] theory view as a modified version of Teleparallel theory. From some important Teleparallel theory results on the localization of energy, our investigations generalize the Landau–Lifshitz prescription from the computation of the energy–momentum complex to the framework of [Formula: see text] gravity as it is done in the modified versions of General Relativity. We compute the energy density in the first step for three plane-symmetric metrics in vacuum. We find for the second metric that the energy density vanishes independently of [Formula: see text] models. We find that the Teleparallel Landau–Lifshitz energy–momentum complex formulations for these metrics are different from those obtained in General Relativity for the same metrics. Second, the calculations are performed for the cosmic string spacetime metric. It results that the energy distribution depends on the mass [Formula: see text] and the radius [Formula: see text] of cosmic string and it is strongly affected by the parameter of the considered quadratic and cubic [Formula: see text] models. Our investigation with this metric induces interesting results susceptible to be tested with some astrophysics hypothesis.

Sudden increase in the degrees of freedom in dense QCD matter

2021 ◽  
Author(s):  
Aditya Nath Mishra ◽  
Guy Paić ◽  
C. Pajares ◽  
R. P. Scharenberg ◽  
B. K. Srivastava
Keyword(s):  
Charged Particle ◽  
Energy Density ◽  
Heavy Ion Collisions ◽  
Degrees Of Freedom ◽  
Initial Temperature ◽  
Heavy Ion ◽  
Particle Multiplicity ◽  
Sudden Increase ◽  
Alice Experiment ◽  
Ion Collisions

In this paper, we analyzed charged particle transverse momentum spectra in high multiplicity events in proton–proton and nucleus–nucleus collisions at LHC energies from the ALICE experiment using the color string percolation model (CSPM). The color reduction factor and associated string density parameters are extracted for various multiplicity classes in [Formula: see text] collisions and centrality classes for heavy-ion collisions at various LHC energies to study the effect of collision geometry and collision energy. These parameters are used to extract the thermodynamical quantities temperature and the energy density of the hot nuclear matter. A universal scaling is observed in initial temperature when studied as a function of charged particle multiplicity scaled by transverse overlap area. From the measured initial energy density [Formula: see text] and the initial temperature T, a dimensionless quantity [Formula: see text] is constructed which is used to obtain the degrees of freedom (DOF) of the deconfined phase. A two-step behavior and a sudden increase in DOF of [Formula: see text]47 for the ideal gas, above the hadronization temperature (T [Formula: see text] 210[Formula: see text]MeV), are observed in case of heavy-ion collisions at LHC energies.

The early universe in a generalized theory of gravitation

1982 ◽  
Vol 60 (5) ◽  
pp. 659-663 ◽  
Author(s):  
J. W. Moffat ◽  
D. Vincent
Keyword(s):  
Early Universe ◽  
Initial Conditions ◽  
Big Bang ◽  
Field Equations ◽  
Anisotropic Solution ◽  
Plane Symmetric ◽  
Frw Model ◽  
Theory Of Gravitation ◽  
The Big Bang ◽  
The Universe

The standard Friedmann–Robertson–Walker (FRW) big-bang model of the universe requires special initial conditions: the early universe is highly homogeneous and isotropic even though there exist causally disconnected regions (horizon problem). A plane symmetric (anisotropic) solution of a system of field equations in a generalized theory of gravitation, predicts the beginning of the universe as a vacuum instability at a specific fundamental time (which can be associated with the Planck time (tp)), after which matter is created as the universe begins to expand. At a time t = tc there is a singular expansion, the anisotropy vanishes, and the physical horizon becomes infinite. Thereafter the solution of the field equations goes over into the FRW model. Thus the special initial conditions of the FRW model at the big-bang singularity t = tc are predicted by the theory.

A note on classification of teleparallel conformal symmetries in non-static plane symmetric space-times in the teleparallel theory of gravitation using diagonal tetrads

2016 ◽  
Vol 13 (04) ◽  
pp. 1650046 ◽  
Author(s):  
Ghulam Shabbir ◽  
Alamgeer Khan ◽  
M. Amer Qureshi ◽  
A. H. Kara
Keyword(s):  
Symmetric Space ◽  
Vector Fields ◽  
Integration Technique ◽  
Plane Symmetric ◽  
Conformal Vector ◽  
Conformal Vector Fields ◽  
Teleparallel Theory ◽  
Theory Of Gravitation ◽  
Static Plane

In this paper, we explore teleparallel conformal vector fields in non-static plane symmetric space-times in the teleparallel theory of gravitation using the direct integration technique and diagonal tetrads. This study will also cover the static plane symmetric space-times as well. In the teleparallel theory curvature of the non-static plane symmetric space-times is zero and the presence of torsion allows more symmetries. In this study after solving the integrabilty conditions it turns out that the dimension of teleparallel conformal vector fields are 5, 6, 7 or 8.

Anisotropic MHRDE model in BD theory of gravitation

2019 ◽  
Vol 16 (12) ◽  
pp. 1950185
Author(s):  
Anirudh Pradhan ◽  
Archana Dixit ◽  
Shilpi Singhal
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Deceleration Parameter ◽  
Big Bang ◽  
Smooth Transition ◽  
Complete Agreement ◽  
Symmetric Model ◽  
Axially Symmetric ◽  
Theory Of Gravitation ◽  
The Universe

In this paper, in the framework of the Brans–Dicke [Phys. Rev. 124 (1961) 925] Gravitation theory, we propose to study the spatially homogeneous, anisotropic and axially symmetric model filled with dark matter and dark energy. Here, we consider the modified holographic Ricci dark energy proposed by Chen and Jing [Phys. Rev. B 679 (2009) 144] as a feasible state of darkness. To achieve a solution, we consider the time-dependent deceleration parameter, which contributes to the average scale factor of [Formula: see text], where [Formula: see text] and [Formula: see text] are arbitrary constants. We have derived field equations of Brans–Dicke theory of gravitation with the help of an axially symmetric anisotropic Bianchi-type space-time. We have determined the cosmological parameters, namely, deceleration parameter, matter energy density, anisotropic dark energy density, BD scalar field, skewness parameter, EoS parameter and jerk parameter. Here, the various phenomena like the Big Bang, expanding the universe, and shift from anisotropy to isotropy are observed in the model. A comprehensive physical debate of these dynamic parameters is provided through a graphical representation. We observe that we have a quintessence model that exhibits a smooth transition from decelerated stage to an accelerated phase of the universe. This situation is in complete agreement with the modern cosmology scenario. Some physical and geometric behaviors are also discussed and discovered to be in excellent agreement with SNe Ia Supernova’s latest observations.

STATIC PLANE SYMMETRIC INTERIOR SOLUTIONS IN f(R) GRAVITY

2013 ◽  
Vol 28 (10) ◽  
pp. 1350041 ◽  
Author(s):  
M. SHARIF ◽  
ZURIAT ZAHRA
Keyword(s):  
Energy Density ◽  
Perfect Fluid ◽  
Ricci Scalar ◽  
Plane Symmetric ◽  
Static Plane ◽  
Interior Solutions

This paper is devoted to explore static plane symmetric solutions in metric f(R) gravity with matter as a perfect fluid. We obtain seven types of solutions. The energy density, pressure and the Ricci scalar are evaluated for each solution. Finally, we find four such solutions which satisfy the required conditions of physically acceptable solutions out of which two are singular and two nonsingular.

scholarly journals Bianchi Types II, VIII, and IX String Cosmological Models in Brans-Dicke Theory of Gravitation

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
V. U. M. Rao ◽  
M. Vijaya Santhi
Keyword(s):  
Energy Density ◽  
Cosmological Model ◽  
Bianchi Type ◽  
Cosmological Models ◽  
Scalar Tensor Theory ◽  
Tensor Theory ◽  
Geometrical Features ◽  
Viii And Ix ◽  
Theory Of Gravitation ◽  
Bianchi Types

Bianchi types II, VIII, and IX string cosmological models are obtained and presented in a scalar-tensor theory of gravitation proposed by Brans and Dicke (1961) for λ+ρ=0. We also established the existence of only Bianchi type IX vacuum cosmological model for λ=ρ, where λ and ρ are tension density and energy density of strings, respectively. Some physical and geometrical features of the models are also discussed.

Sign in / Sign up

Export Citation Format

Share Document