Browsing by Author "KAO, WF"

Now showing 1 - 16 of 16

ANSATZ AND CONSISTENCY
(1991-11-01)
KAO, WF
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交大名義發表
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電子物理學系
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National Chiao Tung University
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Department of Electrophysics
We study the consistency conditions and the implications that come along with an operational definition of an Ansatz. The consistency checks are applied to justify skyrmion and monopole Ansatze. The Friedman-Robertson-Walker metric is discussed. We also comment on Coleman's conjecture and the importance of the spherically symmetric Ansatz.
CONFORMAL GRAVITY WITH TORSION
(1991-08-01)
HAN, P
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KAO, WF
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PEN, UL
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交大名義發表
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光電工程學系
We study a conformal effective theory in the presence of the torsion field. A power-law inflationary solution in the constant gauge is obtained in k = 0 Friedman-Robertson-Walker space. If k not-equal 0, a formal result is also presented. Some technique details are discussed and remarked. It appears that the low energy relic from the torsion field deserves more study.
EXACT SOLUTION IN A SCALE INVARIANT MODEL WITH VANISHING COSMOLOGICAL CONSTANT
(1991-02-01)
KAO, WF
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交大名義發表
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電子物理學系
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National Chiao Tung University
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Department of Electrophysics
We analyze a special scale invariant effective theory with vanishing cosmological constant. We show that, in this theory, the spatial-independence of the inflation is implied by the equation of motion incorporated with the Robertson-Walker metric. Furthermore, we find that this theory can be solved exactly for k = O Robertson-Walker spaces. We also find almost exact solution in k not-equal 0 spaces.
GAUGE-SYMMETRY IN SPINOR SPACE
(1991-10-10)
KAO, WF
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交大名義發表
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電子物理學系
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National Chiao Tung University
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Department of Electrophysics
It is possible to generalize the global similarity transformation in spinor space to a U4 gauge transformation. This gauge transformation is commute with Lorentz transformation if Lorentz transformation is defined in a gauge-covariant way which will be described in this letter. Moreover, this theory is invariant under the conventional U(1) gauge symmetry. Possible implications are also discussed.
GAUGE-SYMMETRY IN SPINOR SPACE
(1991-10-10)
KAO, WF
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電子物理學系
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Department of Electrophysics
It is possible to generalize the global similarity transformation in spinor space to a U4 gauge transformation. This gauge transformation is commute with Lorentz transformation if Lorentz transformation is defined in a gauge-covariant way which will be described in this letter. Moreover, this theory is invariant under the conventional U(1) gauge symmetry. Possible implications are also discussed.
GENERALIZED FRIEDMANN-ROBERTSON-WALKER METRIC AND REDUNDANCY IN THE GENERALIZED EINSTEIN EQUATIONS
(1991-12-15)
KAO, WF
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PEN, UL
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電子物理學系
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Department of Electrophysics
A nontrivial redundancy relation, due to the differential structure of the gravitational Bianchi identity as well as the symmetry of the Friedmann-Robertson-Walker metric, in the gravitational field equation is clarified. A generalized Friedmann-Robertson-Walker metric is introduced in order to properly define a one-dimensional reduced problem which offers an alternative approach to obtain the gravitational field equations on Friedmann-Robertson-Walker spaces.
INDUCED EINSTEIN-KALB-RAMOND THEORY IN 4 DIMENSIONS
(1992-12-15)
KAO, WF
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電子物理學系
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Department of Electrophysics
We analyze a four-dimensional induced Einstein-Kalb-Ramond theory with a conformally coupled Kalb-Ramond action. We also comment on an Ansatz which is inconsistent with the assumption of maximal form invariance imposed on the Kalb-Ramond field due to the cosmological principle. It is argued that the spatial dependences of various fields considered here are inconsistent with the Friedmann-Robertson-Walker metric. One hence justifies the Ansatz used in many articles. We also show that the contribution from the Kalb-Ramond action is negligible effectively after the inflationary era. Some of the solutions to the field equations are presented.
INDUCED-GRAVITY INFLATION REVISITED
(1990-07-09)
KAO, WF
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交大名義發表
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電子物理學系
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National Chiao Tung University
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Department of Electrophysics
INFLATIONARY SOLUTION IN WEYL INVARIANT-THEORY
(1990-09-17)
KAO, WF
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電子物理學系
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Department of Electrophysics
INFLATIONARY SOLUTION IN WEYL INVARIANT-THEORY
(1990-09-17)
KAO, WF
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交大名義發表
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電子物理學系
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National Chiao Tung University
;
Department of Electrophysics
KALUZA-KLEIN INDUCED WEYL INVARIANT EFFECTIVE THEORY
(1992-02-01)
KAO, WF
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交大名義發表
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電子物理學系
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National Chiao Tung University
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Department of Electrophysics
All dimensional parameters in most gravitational models can be promoted to dimensional field variables which can be embedded in some higher dimensional Kaluza-Klein vielbein. An elegant method of computing dimensional reduction process via vielbein and differential form is introduced. We compute the reduced lower dimensional effective scale invariant action after the dimensional reduction takes place. Some applications to the inflationary universe are also discussed.
SCALE-INVARIANCE AND INFLATION
(1991-03-25)
KAO, WF
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交大名義發表
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電子物理學系
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National Chiao Tung University
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Department of Electrophysics
Solving a scale invariant effective theory, we obtain an inflationary solution which is equivalent to an asymptotic boundary condition that has been imposed previously by hand on the scalar field phi, namely, phi-(r --> infinity) --> v. This inflationary solution is unique for a slow roller phi. Possible implications are also discussed. This result signifies the importance of the global scale symmetry.
SCALE-INVARIANT EFFECTIVE ACTION WITH TORSION
(1992-04-01)
KAO, WF
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交大名義發表
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電子物理學系
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National Chiao Tung University
;
Department of Electrophysics
We considered a four-dimensional scale-invariant effective theory with a torsion field conformally coupled to a metric field. We find that the contribution from the torsion field is negligible in the evolution of the early universe. An exact solution is also obtained for k = 0 Friedmann-Robertson-Walker space in the vanishing cosmological constant limit. This solution is also a good approximation to k not-equal 0 spaces. Possible implications to the inflationary universe are also discussed.
SPATIAL DEPENDENCE OF INFLATON IN THE PRESENCE OF THE TORSION FIELD
(1992-03-16)
KAO, WF
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交大名義發表
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電子物理學系
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National Chiao Tung University
;
Department of Electrophysics
We show that, in a class of induced gravity models with (or without) torsion, the associated scalar field (the inflaton) has to be spatial independent in order to admit a Robertson-Walker type solution. Details of the proof are presented. The proof requires a great deal of mathematics which also serves as a pedagogical exercise by itself.
TORSION, COMPACTIFICATION, AND INFLATION
(1993-04-15)
KAO, WF
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電子物理學系
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Department of Electrophysics
We study possible implications of a ten-dimensional Einstein-Kalb-Ramond theory. It is speculated that the compactification process and inflationary process axe closely related. It is also found that the torsion field tends to vanish after the inflation era is completed. This is in fact a general feature for the torsion Lagrangian. Hence the contribution from the Kalb-Ramond action is negligible effectively after the inflationary era. Some solutions to the field equations are also presented.
WILSON LOOP AND CONTOUR SHAPES
(1990-12-15)
KAO, WF
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電子物理學系
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Department of Electrophysics
By computing the Wilson loop expectation value W[C] in the two-dimensional Schwinger model on R1 x S1, we show that nonleading terms depend on the shape of the contours both on R1 x R1 and R1 x S1. We also find that the rhombic contour and triangular contour lead to the same static potentials both on R1 x R1 and R1 x S1. The binding energy is also affected by the choice of contour shapes on the R1 x S1 model. This indicates that the model on R1 x S1 deserves more study.