Origin of the gravitational constant and particle masses in a scale-invariant scalar-tensor theory

1982 ◽  
Vol 26 (10) ◽  
pp. 2580-2588 ◽  
Author(s):  
Yasunori Fujii
Keyword(s):  
Gravitational Constant ◽  
Scalar Tensor Theory ◽  
Scale Invariant ◽  
Tensor Theory ◽  
Invariant Scalar

scholarly journals Gravitoelectromagnetic inflation and seeds of cosmic magnetic fields from geometrical Weyl-invariant scalar–tensor theory of gravity

2019 ◽  
Vol 97 (5) ◽  
pp. 517-523 ◽  
Author(s):  
M. Montes ◽  
José Edgar Madriz Aguilar ◽  
V. Granados
Keyword(s):  
Magnetic Fields ◽  
Power Spectrum ◽  
Electromagnetic Potential ◽  
Scalar Tensor Theory ◽  
Scale Invariant ◽  
Inflaton Field ◽  
Tensor Theory ◽  
Invariant Scalar ◽  
Theory Of Gravity ◽  
Good Agreement

We investigate cosmological inflationary scenarios from a gravitoelectromagnetic theory. Our work is formulated in light of a recently introduced geometrical Weyl-invariant scalar–tensor theory of gravity, where the nature of both the electromagnetic potential and the inflaton field is attributed to the space–time geometry. We obtain a Harrison–Zeldovich power spectrum for quantum fluctuations of the inflaton field. In our model the electromagnetic fields also have a nearly scale-invariant power spectrum for a power-law inflation. We found that the seed magnetic fields have a nearly scale-invariant power spectrum and generate at the present time cosmic magnetic fields of the order ≲10−9 G, in good agreement with CMB observations.

scholarly journals Study of Antigravity in an F(R) Model and in Brans-Dicke Theory with Cosmological Constant

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
V. K. Oikonomou ◽  
N. Karagiannakis
Keyword(s):  
Cosmological Constant ◽  
Lagrange Multipliers ◽  
Gravitational Constant ◽  
Time Dependent ◽  
Jordan Frame ◽  
Scalar Tensor Theory ◽  
Initial Model ◽  
Tensor Theory ◽  
Multipliers Method ◽  
Dicke Model

We study antigravity, that is, having an effective gravitational constant with a negative sign, in scalar-tensor theories originating from F(R) theory and in a Brans-Dicke model with cosmological constant. For the F(R) theory case, we obtain the antigravity scalar-tensor theory in the Jordan frame by using a variant of the Lagrange multipliers method and we numerically study the time dependent effective gravitational constant. As we will demonstrate by using a specific F(R) model, although there is no antigravity in the initial model, it might occur or not in the scalar-tensor counterpart, mainly depending on the parameter that characterizes antigravity. Similar results hold true in the Brans-Dicke model.

scholarly journals FRIEDMANN EQUATION FOR BRANS–DICKE COSMOLOGY

2008 ◽  
Vol 17 (02) ◽  
pp. 225-235 ◽  
Author(s):  
M. ARIK ◽  
M. ÇALIK ◽  
M. B. SHEFTEL
Keyword(s):  
Gravitational Constant ◽  
Friedmann Equation ◽  
Matter Density ◽  
Rate Of Change ◽  
Density Parameter ◽  
Scalar Tensor Theory ◽  
Tensor Theory ◽  
Theory Of Gravitation ◽  
The Universe ◽  
Newtonian Gravitational Constant

In the context of the Brans–Dicke scalar tensor theory of gravitation, the cosmological Friedmann equation which relates the expansion rate H of the universe to the various fractions of energy density is analyzed rigorously. It is shown that the Brans–Dicke scalar tensor theory of gravitation brings a negligible correction to the matter density component of the Friedmann equation. Besides, in addition to ΩΛ and ΩM in the standard Einstein cosmology, another density parameter, ΩΔ, is expected by the theory inevitably. Some cosmological consequences of such nonfamiliar cases are examined as far as recent observational results are concerned. Theory implies that if ΩΔ is found to be nonzero, data can favor this model and hence this theory turns out to be the most powerful candidate in place of the standard Einstein cosmological model with cosmological constant. Such a replacement will enable more accurate predictions for the rate of change of the Newtonian gravitational constant in the future.

A SCALAR-TENSOR THEORY FOR INDUCED GRAVITY

1987 ◽  
Vol 02 (01) ◽  
pp. 179-194 ◽  
Author(s):  
H. BOUTALEB-J. ◽  
A. L. MARRAKCH
Keyword(s):  
Symmetry Breaking ◽  
Spontaneous Symmetry Breaking ◽  
Gravitational Constant ◽  
Low Energy ◽  
Scalar Tensor Theory ◽  
Energy Limit ◽  
Potential Minimum ◽  
Induced Gravity ◽  
Tensor Theory ◽  
The Universe

A scalar-tensor theory for induced gravity is presented. Einstein's gravity appears as the low-energy limit of such a theory. It is shown that the spontaneous symmetry breaking can occur at any epoch of the universe and that this mechanism can also be responsible for breaking the unified gauge group SU(5) into SU (3) × SU (2) × U (1). Also, it is shown that, if the spontaneous symmetry breaking is accomplished by means of the Coleman-Weinberg potential minimum, the induced gravitational constant can, with a suitable choice of the coupling function, increase as one dates back.

scholarly journals THE VARIATION OF THE GRAVITATIONAL CONSTANT INFERRED FROM THE HUBBLE DIAGRAM OF TYPE Ia SUPERNOVAE

2006 ◽  
Vol 15 (08) ◽  
pp. 1163-1174 ◽  
Author(s):  
ENRIQUE GARCIA-BERRO ◽  
YURI KUBYSHIN ◽  
PABLO LOREN-AGUILAR ◽  
JORDI ISERN
Keyword(s):  
Fine Structure ◽  
Gravitational Constant ◽  
Structure Constant ◽  
Fine Structure Constant ◽  
Type Ia Supernovae ◽  
Scalar Tensor Theory ◽  
Hubble Diagram ◽  
Tensor Theory ◽  
Type Ia ◽  
Ia Supernovae

We consider a cosmological model with a variable gravitational constant, G, based on a scalar–tensor theory. Using the recent observational data for the Hubble diagram of type Ia supernovae (SNeIa), we find a phenomenological expression describing the variation of G. The corresponding variation of the fine structure constant α within multidimensional theories is also computed and is shown not to support known constraints on Δα/α.

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