scholarly journals TIME IN THE SEMICLASSICAL APPROXIMATION TO QUANTUM GRAVITY COUPLED WITH A BACKGROUND SCALAR FIELD AND KALUZA-KLEIN THEORY

1995 ◽  
Vol 10 (13) ◽  
pp. 1905-1915
Author(s):  
YOSHIAKI OHKUWA
Keyword(s):  
Scalar Field ◽  
Quantum Gravity ◽  
Semiclassical Approximation ◽  
Matter Field ◽  
Time Variable ◽  
Time Coordinate ◽  
Quantum Matter ◽  
Klein Theory ◽  
Original Time ◽  
Kaluza Klein

We consider the semiclassical approximation to quantum gravity coupled with a background scalar field and a quantum matter field. We define the semiclassical time variable and write down the Schrödinger equation for the quantum matter field. This can be rewritten into the form whose time variable is the original time coordinate, when the relation of Hamilton-Jacobi holds. It is shown that the four-dimensional semiclassical time with a background scalar field is related to the five-dimensional semiclassical time without it by means of the Kaluza-Klein dimensional reduction.

scholarly journals TIME IN THE CHAOTIC INFLATION MODEL AND NUMERICAL CALCULATIONS

1995 ◽  
Vol 10 (16) ◽  
pp. 2317-2332
Author(s):  
YOSHIAKI OHKUWA ◽  
TETSURO KITAZOE ◽  
YOSHIHIKO MIZUMOTO
Keyword(s):  
Quantum Gravity ◽  
Perturbation Method ◽  
Orbital Motion ◽  
Semiclassical Approximation ◽  
Natural Extension ◽  
Matter Field ◽  
Time Variable ◽  
Inflation Model ◽  
Scalar Matter ◽  
Scalar Mass

The time variable is considered in the quantum gravity theory and calculated explicitly in the framework of the chaotic inflationary scenario where the scalar matter field has a contribution to the time variable in addition to the gravity field. The time formulated under the semiclassical approximation is a natural extension of that in the classical orbital motion. A perturbation method is introduced in terms of the scalar mass to obtain analytically solvable expressions for the time. The Wheeler-DeWitt equation is solved numerically to ensure that the semiclassical approximation is well justified. We examine the obtained time in detail and find that it is reasonable to consider it as time in the region where the semiclassical approximation is well justified.

scholarly journals Wave Packet in Quantum Cosmology and Definition of Semiclassical Time

1997 ◽  
Vol 12 (05) ◽  
pp. 859-871
Author(s):  
Y. Ohkuwa ◽  
T. Kitazoe
Keyword(s):  
Wave Function ◽  
Scalar Field ◽  
Wave Packet ◽  
Quantum Cosmology ◽  
Matter Field ◽  
Time Variable ◽  
Wave Functions ◽  
Quantum Matter ◽  
Definition Of ◽  
The Universe

We consider a quantum cosmology with a massless background scalar field ϕB and adopt a wave packet as the wave function. This wave packet is a superposition of the WKB form wave functions, each of which has a definite momentum of the scalar field ϕB. In this model it is shown that to trace the formalism of the WKB time is seriously difficult without introducing a complex value for a time. We define a semiclassical real time variable TP from the phase of the wave packet and calculate it explicitly. We find that, when a quantum matter field ϕQ is coupled to the system, an approximate Schrödinger equation for ϕQ holds with respect to TP in a region where the size a of the universe is large and |ϕB| is small.

Experimental tests of an improved 5D Kaluza-Klein theory

2020 ◽  
Vol 35 (02n03) ◽  
pp. 2040027
Author(s):  
Jean Paul Mbelek
Keyword(s):  
Experimental Data ◽  
Scalar Field ◽  
Experimental Tests ◽  
Torsion Pendulum ◽  
Klein Theory ◽  
Kaluza Klein

We recall the motivation for an external scalar field, [Formula: see text], and show how it helps to improve the 5D Kaluza-Klein theory. Various applications of the theory that fit observational or experimental data in the laboratory as well as in the cosmological or astrophysical contexts are mentioned. Special attention is given to the last version of the experiment showing evidence of a torque on a torsion pendulum as predicted by the theory. New arguments that motivate extradimensions are put forward.

scholarly journals GAUGE THEORIES AS A GEOMETRICAL ISSUE OF A KALUZA–KLEIN FRAMEWORK

2005 ◽  
Vol 14 (07) ◽  
pp. 1195-1231 ◽  
Author(s):  
FRANCESCO CIANFRANI ◽  
ANDREA MARROCCO ◽  
GIOVANNI MONTANI
Keyword(s):  
Gauge Theory ◽  
Scalar Field ◽  
Symmetry Breaking ◽  
Gauge Theories ◽  
Dimensional Manifold ◽  
Unification Theory ◽  
Klein Theory ◽  
Electroweak Model ◽  
Quark Generation ◽  
Kaluza Klein

We present a geometrical unification theory in a Kaluza–Klein approach that achieve the geometrization of a generic gauge theory bosonic component. We show how it is possible to derive gauge charge conservation from the invariance of the model under extra-dimensional translations and to geometrize gauge connections for spinors, in order to make possible to introducing matter just through free spinorial fields. Then we present the applications to (i) a pentadimensional manifold V4 ⊗ S1 so reproducing the original Kaluza–Klein theory with some extensions related to the rule of the scalar field contained in the metric and to the introduction of matter through spinors with a phase dependance from the fifth coordinate, (ii) a seven-dimensional manifold V4 ⊗ S1 ⊗ S2, in which we geometrize the electroweak model by introducing two spinors for every leptonic family and quark generation and a scalar field with two components with opposite hypercharge responsible for spontaneous symmetry breaking.

scholarly journals KALUZA–KLEIN SOLITONS RE-EXAMINED

2008 ◽  
Vol 17 (02) ◽  
pp. 237-256 ◽  
Author(s):  
J. PONCE DE LEON
Keyword(s):  
Geometrical Approach ◽  
Black String ◽  
String Solution ◽  
Time Coordinate ◽  
Single Solution ◽  
Klein Theory ◽  
Zero Moment ◽  
Induced Matter ◽  
Kaluza Klein ◽  
Owen Set

In 4 + 1 gravity the assumption that the five-dimensional metric is independent of the fifth coordinate permits the extra dimension to be either spacelike or timelike. As a consequence of this, the time coordinate and the extra coordinate are interchangeable, which in turn allows the conception of different scenarios in 4D from a single solution in 5D. In this paper, we make a thorough investigation of all possible 4D scenarios, associated with this interchange, for the well-known Kramer–Gross–Perry–Davidson–Owen set of solutions. We show that there are three families of solutions with very distinct geometrical and physical properties. They correspond to different sets of values of the parameters which characterize the solutions in 5D. The solutions of physical interest are identified on the basis of physical requirements on the induced matter in 4D. We find that only one family satisfies these requirements; the other two violate the positivity of mass-energy density. The "physical" solutions possess a lightlike singularity which coincides with the horizon. The Schwarzschild black string solution as well as the zero moment dipole solution of Gross and Perry are obtained in different limits. These are analyzed in the context of Lake's geometrical approach. We demonstrate that the parameters of the solutions in 5D are not free, as previously considered. Instead, they are totally determined by measurements in 4D — namely, by the surface gravitational potential of the astrophysical phenomena, like the Sun or other stars, modeled in Kaluza–Klein theory. This is an important result which may help in observations for an experimental/observational test of the theory.

DIRAC FIELD IN THE FIVE-DEMENSIONAL KALUZA-KLEIN THEORY WITH SCALAR FIELD

1992 ◽  
Vol 07 (21) ◽  
pp. 5105-5113 ◽  
Author(s):  
A. MACÍAS ◽  
H. DEHNEN
Keyword(s):  
Scalar Field ◽  
Dirac Equation ◽  
Ground State ◽  
Mass Term ◽  
Dirac Field ◽  
Electron Mass ◽  
Dimensional Theory ◽  
Klein Theory ◽  
Kaluza Klein

In this work we investigate the five-dimensional Kaluza-Klein theory with a scalar field contained in the metric, where a Dirac-field is coupled to the metric field. We find that in the four-dimensional theory a nontrivial ground state for the scalar field exists and therefore the mass term in the Dirac equation can be interpreted, for example, as the electron mass.

scholarly journals PALATINI FORMALISM OF FIVE-DIMENSIONAL KALUZA–KLEIN THEORY

2005 ◽  
Vol 20 (05) ◽  
pp. 345-353 ◽  
Author(s):  
YOU DING ◽  
YONGGE MA ◽  
MUXIN HAN ◽  
JIANBING SHAO
Keyword(s):  
Vector Field ◽  
Scalar Field ◽  
Killing Vector ◽  
Killing Vector Field ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Palatini Formalism ◽  
Klein Theory ◽  
Kaluza Klein

The Einstein field equations can be derived in n dimensions (n>2) by the variations of the Palatini action. The Killing reduction of five-dimensional Palatini action is studied on the assumption that pentads and Lorentz connections are preserved by the Killing vector field. A Palatini formalism of four-dimensional action for gravity coupled to a vector field and a scalar field is obtained, which gives exactly the same field equations in Kaluza–Klein theory.

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