Is N=4 ONLY a mathematical construct?

[jal]

What are your thoughts.

Some questions ... If we have a 4th space dimension:
What does it look like? (A brane is 2d)
What is in it? (Gravity, dark energy)
Can a 2d or 3d “particle” be residing or coming from a one dimension?
Do parts of a “particle” exist in ALL of the 4 dimension?
Do virtual particles exist in other dimensions when they are not activated to “exist’ in our euclidean space?
Does the quark gluon plasma occupy euclidean space and the 4th dimension?
Is confinement of protons restricted to euclidean space?
jal

 

[jal]

http://arxiv.org/abs/1101.1081
General Covariance in Gravity at a Lifgarbagez Point
Petr Horava
(Submitted on 5 Jan 2011)
It is natural to ask whether one can construct theories with anisotropic scaling and with propagating gravitons. Why? A consistent theory of gravity with anisotropic scaling can be potentially useful for a number of possible applications:

(i) Phenomenology of gravity in our Universe of 3 + 1 macroscopic dimensions.
(ii) New gravity duals for field theories in the context of the AdS/CFT correspondence; in
particular, duals for a broader class of nonrelativistic QFTs.
(iii) Gravity on worldsheets of strings and worldvolumes of branes.
(iv) Mathematical applications to the theory of the Ricci flow on Riemannian manifolds [1].
(v) IR fixed points in condensed matter systems, with emergent gravitons (new phases of
algebraic bose liquids) [5].
(vi) Relativistic gravity and string theory in asymptotically anisotropic spacetimes [6];
and possibly others.

Note that only application (i) is subjected to the standard observational tests of gravity, while the others are only constrained by their mathematical consistency.


How can the effective dimension of spacetime change continuously from four at long distances to two at short distances? An analytic explanation was offered in [3]: The spectral dimension is a precisely defined geometric quantity, and it can be calculated systematically in the continuum approach to quantum gravity with anisotropic scaling. In the mean-field approximation around the flat spacetime, the result is [3] ds = 1 + D z . (1.7)
Hence, if the gravity theory flows from a z = 3 UV fixed point to a z = 1 IR fixed point, the qualitative crossover of ds observed in [19] is reproduced.

The topological dimension of spacetime is always four, but the spectral dimension changes because of the anisotropic scaling at short distances.
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This approach raises another interesting question.
Are we going to be limited to only observing the surface of the perfect liquid, (quark-gluon plasma ball), at CERN?

jal

 

[jal]

This seems to be another mathematical consistency approach.

Now where are the observations?

http://arxiv.org/abs/1101.1424

On Gravity, Torsion and the Spectral Action Principle
Frank Pfaeffle, Christoph A. Stephan
(Submitted on 7 Jan 2011)
We consider closed Riemannian spin manifolds with orthogonal connections. We regard the induced Dirac operators and the associated commutative spectral triples. In case of dimension four we compute the Chamseddine-Connes spectral action, deduce the equations of motions and discuss critical points.

 

[jal]

I have picked out a few presentation from the corfu conference.
If you don't agree with my pick then there might be another presentation that supports you views.

http://www.physics.ntua.gr/corfu2010/lectures.html
corfu2010
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http://www.physics.ntua.gr/corfu2010/Talks/cthan@mail_ntua_gr_01.pdf
Fuzzy extra dimensions and particle physics models
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http://www.physics.ntua.gr/corfu2010/Talks/geraldine_servant@cern_ch_01.pdf
Cosmology and Physics Beyond the SM
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http://www.physics.ntua.gr/corfu2010/Talks/faguila@ugr_es_01.pdf
Electroweak contraints on new physics