7 papers from Thiemann's Erlangen group, going into Loops 2011 conf.

[marcus]

The Erlangen group just posted 7 papers: a series developing an new canonical approach to LQG more explicitly able to generalize to spatial D > 3, also possibly with some advantage in accommodating matter.

Thiemann has been invited to address the Loops conference at Madrid and present the main outlines.
He will speak at the morning plenary session on the second day of the conference, Tuesday 24 May, between 10 and 11.

Also 4 parallel session time-slots have been provided for his co-authors Thurn and Bodendorfer to present specific aspects and details of the new approach.
http://www.iem.csic.es/loops11/

Their talks will be on Thursday 26 May starting at 15:25, and on Friday 27 May beginning 14:45 in the appropriate afternoon sessions. As noted, the Erlangen approach is canonical and there are two sessions at the conference specifically devoted to Hamiltonian LQG.

This comes as something of a surprise to me. I didn't know this was in the works. Until recently the conference programme just said "TBA" (to be announced) for these talks, instead of giving titles. I couldn't find any recent papers from Thiemann's groups that suggested what they might be presenting. So from the standpoint of an outside observer they are only just now making their work public.

It's possible that some others here at Beyond forum knew earlier, if they were closer to the Erlangen QG group. It may be a case where I was just slow to catch on. Tom Stoer I think pays closer attention and he may have known about this research.

 

[marcus]

Abstracts of the 7 new papers are transcribed here:
https://www.physicsforums.com/showthread.php?p=3310074#post3310074

The URLs are:

http://arxiv.org/abs/1105.3703
New Variables for Classical and Quantum Gravity in all Dimensions I. Hamiltonian Analysis

http://arxiv.org/abs/1105.3704
New Variables for Classical and Quantum Gravity in all Dimensions II. Lagrangian Analysis

http://arxiv.org/abs/1105.3705
New Variables for Classical and Quantum Gravity in all Dimensions III. Quantum Theory

http://arxiv.org/abs/1105.3706
New Variables for Classical and Quantum Gravity in all Dimensions IV. Matter Coupling

http://arxiv.org/abs/1105.3708
On the Implementation of the Canonical Quantum Simplicity Constraint

http://arxiv.org/abs/1105.3709
Towards Loop Quantum Supergravity (LQSG) I. Rarita-Schwinger Sector

http://arxiv.org/abs/1105.3710
Towards Loop Quantum Supergravity (LQSG) II. p-Form Sector

 

[Kevin_Axion]

What's the motivation of going into the SUGRA sector?

 

[marcus]

What's the motivation of going into the SUGRA sector?

Hi Kevin , just read the abstract of the very first paper!

"...this method is restricted to D+1 = 4 spacetime dimensions. However, interesting String theories and Supergravity theories require higher dimensions and it would therefore be desirable to have higher dimensional Supergravity loop quantisations at one's disposal in order to compare these approaches. In this series of papers..."

For me as a mathematician there is a kind of widespread bias in favor of generality. It often pays to try to see if you can generalize a theorem. You often learn something by doing that.

So it isn't necessary to be able to give a specific motive, to say in advance what might be gained. There is just a general feeling (among mathematicians) that it is a good idea, or it might be a good idea in many cases. To see how much you can generalize a procedure or definition or result.

Thiemann is more specific, he says you could want this so you can COMPARE. See if this and that are consistent, by putting them to the same task. Who knows? perhaps one could falsify some version of Loop by applying it somewhere and showing that it gives the wrong answer! Consistency tests. All sorts of good things like that. I'm being very vague, but I think there is some sense to what Thiemann says about it being "desirable".

Anyone else could answer. Maybe someone else has a specific idea of something definite that could be obtained by including Sugra in the picture. I just have a this vague instinctive feeling that generalizing is one of those things that are good to try and that sometimes lead to unexpected revelations.

 

[Kevin_Axion]

Interesting. I just found it odd that SUGRA gains most of its beauty and usefulness in it's 11-dimensional representation and LQG in its 4-dimensional representation and they're trying to "merge" them.

 

[marcus]

Interesting. I just found it odd that SUGRA gains most of its beauty and usefulness in it's 11-dimensional representation and LQG in its 4-dimensional representation and they're trying to "merge" them.

I understand, but I already explained my take on it: that they are not trying to merge 4D LQG with 11D something or other. They are generalizing the LQG machinery so that they have the option of running 10+1 D or of running Sugra, and being able to see what happens when they do that. Personally I would like that, not because I suppose that nature is 10+1 dimensional or has supersymmetry. But because the theory overlap could be challenging and conceptually fertile to explore.

 

[atyy]

What's the motivation of going into the SUGRA sector?

These papers form Thiemann and colleagues are probably very canonical in outlook, but there has been interesting work done on supersymmetry on the spin foam side. The spin foam papers are in 3D, Thiemann is aiming for 10D. If we believe ABJM, then a 3D supersymmetric gauge theory will correspond to supergravity in AdS₄XS⁷ (10D) www.ictp.it/media/101047/schwarzictp.pdf.

http://arxiv.org/abs/1004.0672
http://arxiv.org/abs/0710.3540