Kaluza–Klein-type models of de Sitter and Poincaré gauge theories of gravity

The existence of a small and positive cosmological constant attributed to gravitational vacuum energy (or dark energy) in the present-day universe appears to be the most pressing obstacle as well as opportunity to significantly improving the models of four-dimensional cosmology from fundamental theories of gravity, including string theory and modern Kaluza-Klein theories. In seeking to resolve this problem, one naturally wonders if the real world can somehow be interpreted as an inflating de Sitter "brane" embedded in a five or even higher-dimensional space-time described by warped or non-factorizable geometry. In this scenario, the four-dimensional cosmological constant may well be determined in terms of two length scales: one is a scale associated with the size of extra dimensions and the other is a scale associated with the expansion rate of the universe, which is also related to the warping of extra spaces.Key words: CosmologyThe Himalayan Physics Vol.1, No.1, May, 2010Page: 18-24Uploaded Date: 28 July, 2011

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Canonical transformation path to gauge theories of gravity

Physical Review D ◽

10.1103/physrevd.95.124048 ◽

2017 ◽

Vol 95 (12) ◽

Cited By ~ 11

Author(s):

J. Struckmeier ◽

J. Muench ◽

D. Vasak ◽

J. Kirsch ◽

M. Hanauske ◽

...

Keyword(s):

Canonical Transformation ◽

Gauge Theories ◽

Transformation Path ◽

Theories Of Gravity

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ANTI-DE SITTER SPACE, THERMAL PHASE TRANSITION AND CONFINEMENT IN GAUGE THEORIES

International Journal of Modern Physics A ◽

10.1142/s0217751x01004451 ◽

2001 ◽

Vol 16 (16) ◽

pp. 2747-2769 ◽

Cited By ~ 6

Author(s):

EDWARD WITTEN

Keyword(s):

Gauge Theories ◽

De Sitter Space ◽

Spontaneous Breaking ◽

De Sitter ◽

Four Dimensions ◽

Yang Mills ◽

Conformal Field ◽

Classical Geometry ◽

Large N ◽

Quantum Phenomena

The correspondence between supergravity (and string theory) on AdS space and boundary conformal field theory relates the thermodynamics of [Formula: see text] super-Yang–Mills theory in four dimensions to the thermodynamics of Schwarzschild black holes in anti-de Sitter space. In this description, quantum phenomena such as the spontaneous breaking of the center of the gauge group, magnetic confinement and the mass gap are coded in classical geometry. The correspondence makes it manifest that the entropy of a very large AdS Schwarzschild black hole must scale "holographically" with the volume of its horizon. By similar methods, one can also make a speculative proposal for the description of large N gauge theories in four dimensions without supersymmetry.

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GRAVITATION, THERMODYNAMICS, AND THE BOUND ON VISCOSITY

International Journal of Modern Physics D ◽

10.1142/s0218271809016132 ◽

2009 ◽

Vol 18 (14) ◽

pp. 2337-2341

Author(s):

SHAHAR HOD

Keyword(s):

Field Theory ◽

Gauge Theories ◽

Entropy Density ◽

De Sitter ◽

Small Perturbations ◽

General Validity ◽

Small Deviations ◽

Conformal Field ◽

Direct Outcome ◽

Recent Attention

The anti-de Sitter/conformal field theory (AdS/CFT) correspondence implies that small perturbations of a black hole correspond to small deviations from thermodynamic equilibrium in a dual field theory. For gauge theories with an Einstein gravity dual, the AdS/CFT correspondence predicts a universal value for the ratio of the shear viscosity to the entropy density, η/s = 1/4π. It was conjectured recently that all fluids conform to the lower bound: η/s ≥ 1/4π. This conjectured bound has been the focus of much recent attention. However, despite the flurry of research in this field we still lack a proof for the general validity of the bound. In this essay we show that this mysterious bound is actually a direct outcome of the interplay between gravity, quantum theory, and thermodynamics.

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