SPONTANEOUS CONTRACTION

1988 ◽  
Vol 03 (15) ◽  
pp. 1473-1477 ◽  
Author(s):  
Y.M. CHO ◽  
P.Y. PAC
Keyword(s):  
Spontaneous Contraction ◽  
Internal Space ◽  
Higher Dimensional ◽  
Kaluza Klein

The phenomenon of a spontaneous contraction in higher-dimensional geometric theories of Kaluza-Klein type is discussed which could lead to a spontaneous decompactification of the internal space. In a spontaneous contraction, an isometry G is contracted to G′ by the vacuum which often breaks G′ further down to H spontaneously.

INFLATION IN KALUZA-KLEIN COSMOLOGY I: TRANSFORMATION TO FOURTH-ORDER GRAVITY

1990 ◽  
Vol 05 (24) ◽  
pp. 4661-4669 ◽  
Author(s):  
HANS-JÜRGEN SCHMIDT
Keyword(s):  
Fourth Order ◽  
Arbitrary Dimension ◽  
Internal Space ◽  
Vacuum Equation ◽  
Scale Invariant ◽  
Einstein Vacuum Equation ◽  
Higher Dimensional ◽  
Einstein Vacuum ◽  
Klein Model ◽  
Kaluza Klein

The higher-dimensional Einstein vacuum equation with Λ-term is shown to be conformally equivalent to the four-dimensional field equation of scale-invariant fourth-order gravity. This holds for a general warped product between space-time and internal space of arbitrary dimension m which turns out to be an Einstein space. (The limit m → ∞ makes sense!) Thus, the results concerning the attractor property of the power-law inflationary solution derived for fourth-order gravity hold for the Kaluza-Klein model, too.

scholarly journals Unitarity in KK-graviton production, a case study in warped extra-dimensions

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
A. de Giorgi ◽  
S. Vogl
Keyword(s):  
Extra Dimensions ◽  
Sum Rules ◽  
Effective Theory ◽  
Higher Dimensional ◽  
Massive Spin ◽  
The Matrix ◽  
Dimensional Gravity ◽  
Warped Extra Dimensions ◽  
Kaluza Klein

Abstract The Kaluza-Klein (KK) decomposition of higher-dimensional gravity gives rise to a tower of KK-gravitons in the effective four-dimensional (4D) theory. Such massive spin-2 fields are known to be connected with unitarity issues and easily lead to a breakdown of the effective theory well below the naive scale of the interaction. However, the breakdown of the effective 4D theory is expected to be controlled by the parameters of the 5D theory. Working in a simplified Randall-Sundrum model we study the matrix elements for matter annihilations into massive gravitons. We find that truncating the KK-tower leads to an early breakdown of perturbative unitarity. However, by considering the full tower we obtain a set of sum rules for the couplings between the different KK-fields that restore unitarity up to the scale of the 5D theory. We prove analytically that these are fulfilled in the model under consideration and present numerical tests of their convergence. This work complements earlier studies that focused on graviton self-interactions and yields additional sum rules that are required if matter fields are incorporated into warped extra-dimensions.

4D Einstein equations in a general gauge Kaluza–Klein space

2015 ◽  
Vol 12 (03) ◽  
pp. 1550036
Author(s):  
Aurel Bejancu ◽  
Constantin Călin
Keyword(s):  
Einstein Equations ◽  
Tensor Fields ◽  
New Approach ◽  
Higher Dimensional ◽  
High Level ◽  
General Gauge ◽  
Kaluza Klein

Using the new approach on higher-dimensional Kaluza–Klein theories developed by the first author, we obtain the 4D Einstein equations on a (4 + n)D relativistic gauge Kaluza–Klein space. Adapted frame and coframe fields, adapted tensor fields, and the Riemannian adapted connection, have a fundamental role in the study. The high level of generality of the study, enables us to recover several results from earlier papers on this matter.

GRAVITATIONAL BAG EFFECTS ON KALUZA KLEIN AND STRING EXCITATIONS

1989 ◽  
Vol 04 (19) ◽  
pp. 5119-5131 ◽  
Author(s):  
E. I. GUENDELMAN
Keyword(s):  
Extra Dimensions ◽  
Blow Up ◽  
Point Of View ◽  
Spherically Symmetric ◽  
Massive String ◽  
Free Objects ◽  
Higher Dimensional ◽  
Central Regions ◽  
The Masses ◽  
Kaluza Klein

Gravitational Bags are spherically symmetric solutions of higher-dimensional Kaluza Klein (K – K) theories, where the compact dimensions become very large near the center of the geometry, although they are small elsewhere. The K – K excitations therefore become very light when located near the center of this geometry and this appears to affect drastically the naive tower of the masses spectrum of K – K theories. In the context of string theories, string excitations can be enclosed by Gravitational Bags, making them not only lighter, but also localized, as observed by somebody, that does not probe the central regions. Strings, however, can still have divergent sizes, as quantum mechanics seems to demand, since the extra dimensions blow up at the center of the geometry. From a projected 4-D point of view, very massive string bits may lie inside their Schwarzschild radii, as pointed out by Casher, Gravitational Bags however are horizon free objects, so no conflict with macroscopic causality arises if the string excitations are enclosed by Gravitational Bags.

scholarly journals KALUZA–KLEIN DIMENSIONAL REDUCTION AND GAUSS–CODAZZI–RICCI EQUATIONS

2009 ◽  
Vol 24 (06) ◽  
pp. 1207-1220
Author(s):  
PEI WANG
Keyword(s):  
General Relativity ◽  
Dimensional Reduction ◽  
Traditional Method ◽  
Isometry Group ◽  
Extrinsic Curvature ◽  
Internal Space ◽  
Geometric Meaning ◽  
Reduced Dimensions ◽  
Lower Dimensional ◽  
Kaluza Klein

In this paper we imitate the traditional method which is used customarily in the general relativity and some mathematical literatures to derive the Gauss–Codazzi–Ricci equations for dimensional reduction. It would be more distinct concerning geometric meaning than the vielbein method. Especially, if the lower-dimensional metric is independent of reduced dimensions the counterpart of the symmetric extrinsic curvature is proportional to the antisymmetric Kaluza–Klein gauge field strength. For isometry group of internal space, the SO (n) symmetry and SU (n) symmetry are discussed. And the Kaluza–Klein instanton is also enquired.

scholarly journals MULTI-DIMENSIONAL COSMOLOGY AND DSR–GUP

2013 ◽  
Vol 28 (12) ◽  
pp. 1350047 ◽  
Author(s):  
K. ZEYNALI ◽  
F. DARABI ◽  
H. MOTAVALLI
Keyword(s):  
Cosmological Constant ◽  
Generalized Uncertainty Principle ◽  
Internal Space ◽  
Positive Cosmological Constant ◽  
Doubly Special Relativity ◽  
Dimensional Spacetime ◽  
Higher Dimensional ◽  
Big Crunch ◽  
The Difference ◽  
Cosmological Constants

A multi-dimensional cosmology with FRW type metric having four-dimensional spacetime and d-dimensional Ricci-flat internal space is considered with a higher-dimensional cosmological constant. The classical cosmology in commutative and Doubly Special Relativity–Generalized Uncertainty Principle (DSR–GUP) contexts is studied and the corresponding exact solutions for negative and positive cosmological constants are obtained. In the positive cosmological constant case, it is shown that unlike the commutative as well as GUP cases, in DSR–GUP case both scale factors of internal and external spaces after accelerating phase will inevitably experience decelerating phase leading simultaneously to a big crunch. This demarcation from GUP originates from the difference between the GUP and DSR–GUP algebras. The important result is that unlike GUP which results in eternal acceleration, DSR–GUP at first generates acceleration but prevents the eternal acceleration at late-times and turns it into deceleration.

scholarly journals A new class of higher-dimensional Kaluza-Klein monopole and instanton solutions

1985 ◽  
Vol 253 ◽  
pp. 162-172 ◽  
Author(s):  
F. Alexander Bais ◽  
Peter Batenburg
Keyword(s):  
New Class ◽  
Higher Dimensional ◽  
Kaluza Klein

scholarly journals Kaluza-Klein Multidimensional Models with Ricci-Flat Internal Spaces: The Absence of the KK Particles

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Alexey Chopovsky ◽  
Maxim Eingorn ◽  
Alexander Zhuk
Keyword(s):  
Statistical Physics ◽  
Internal Space ◽  
Nonzero Temperature ◽  
Ricci Flat ◽  
Radar Echoes ◽  
Astrophysical Objects ◽  
Correction Terms ◽  
Multidimensional Models ◽  
Metric Fluctuations ◽  
Kaluza Klein

We consider a multidimensional Kaluza-Klein (KK) model with a Ricci-flat internal space, for example, a Calabi-Yau manifold. We perturb this background metrics by a system of gravitating masses, for example, astrophysical objects such as our Sun. We suppose that these masses are pressureless in the external space but they have relativistic pressure in the internal space. We show that metric perturbations do not depend on coordinates of the internal space and gravitating masses should be uniformly smeared over the internal space. This means, first, that KK modes corresponding to the metric fluctuations are absent and, second, particles should be only in the ground quantum state with respect to the internal space. In our opinion, these results look very unnatural. According to statistical physics, any nonzero temperature should result in fluctuations, that is, in KK modes. We also get formulae for the metric correction terms which enable us to calculate the gravitational tests: the deflection of light, the time-delay of the radar echoes, and the perihelion advance.

scholarly journals Looking for (and not finding) a bulk brane

2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
Wyatt Reeves ◽  
Moshe Rozali ◽  
Petar Simidzija ◽  
James Sully ◽  
Christopher Waddell ◽  
...  
Keyword(s):  
Causal Structure ◽  
Internal Space ◽  
Higher Dimensional ◽  
The World ◽  
Holographic Duals ◽  
End Of The World

Abstract When does a holographic CFT with a boundary added to it (a BCFT) also have a ‘good’ holographic dual with a localized gravitating end-of-the-world brane? We argue that the answer to this question is almost never. By studying Lorentzian BCFT correlators, we characterize constraints imposed on a BCFT by the existence of a bulk causal structure. We argue that approximate ‘bulk brane’ singularities place restrictive constraints on the spectrum of a BCFT that are not expected to be true generically. We discuss how similar constraints implied by bulk causality might apply in higher-dimensional holographic descriptions of BCFTs involving a degenerating internal space. We suggest (although do not prove) that even these higher-dimensional holographic duals are not generic.

scholarly journals Gauge Theories: From Kaluza–Klein to noncommutative gravity theories

Symmetry ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 856
Author(s):  
George Manolakos ◽  
Pantelis Manousselis ◽  
George Zoupanos
Keyword(s):  
Dimensional Reduction ◽  
Particle Physics ◽  
Extra Dimensions ◽  
Gauge Theories ◽  
Dimensional Theory ◽  
Higher Dimensional ◽  
Coset Spaces ◽  
Gravity Theories ◽  
Physics Model ◽  
Kaluza Klein

First, the Coset Space Dimensional Reduction scheme and the best particle physics model so far resulting from it are reviewed. Then, a higher-dimensional theory in which the extra dimensions are fuzzy coset spaces is described and a dimensional reduction to four-dimensional theory is performed. Afterwards, another scheme including fuzzy extra dimensions is presented, but this time the starting theory is four-dimensional while the fuzzy extra dimensions are generated dynamically. The resulting theory and its particle content is discussed. Besides the particle physics models discussed above, gravity theories as gauge theories are reviewed and then, the whole methodology is modified in the case that the background spacetimes are noncommutative. For this reason, specific covariant fuzzy spaces are introduced and, eventually, the program is written for both the 3-d and 4-d cases.

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