Critical recorded seminar talk by PF member

[marcus]

Anyone interested in following LQG research may wish to listen to Frank Hellmann's talk.
Download the slides PDF first before starting the audio. He will say when to advance to the next slide as he goes thru the talk. This gives a clear concise overview of a reformulation of LQG led by Bianca Dittrich (MPI-Potsdam and now Perimeter)

Here is my 7 September post about it:
==quote==
Frank Hellmann's 4 September online seminar talk
http://relativity.phys.lsu.edu/ilqgs/hellmann090412.pdf
http://relativity.phys.lsu.edu/ilqgs/hellmann090412.wav
...
...
For more information about the ILQGS series of talks:
http://relativity.phys.lsu.edu/ilqgs/
http://relativity.phys.lsu.edu/ilqgs/schedulefa12.html
==endquote==

We can be a little proud that several of today's most active Loop researchers have been PF members and have posted (some quite a lot) over the past several years--e.g. Hellmann, Vidotto, Corichi, Livine...Hellmann's talk is about 3 papers, one of which has already appeared on Arxiv, the other two expected to appear soon. People who occasionally come with questions like "what is LQG" or who comment on possibly outmoded versions they have read about may want to check these papers out as they appear..

* B. Bahr, B. Dittrich, FH, W. Kaminski:
Holonomy Spin Foam Models: Definition and coarse graining.
(arxiv:1208:3388),
Holonomy Spin Foam Models: Boundary Hilbert spaces and canonical dynamics. (arxiv:soon)
* FH, W. Kaminski:
Holonomy Spin Foam Models: Asymptotic Dynamics of EPRL type
models. (arxiv: soon+ε)

The authors are at Perimeter, MPI-Potsdam (Albert Einstein Institute), and Cambridge DAMPT. The abstract for the first of the three papers is:
==quote==
We propose a new holonomy formulation for spin foams, which naturally extends the theory space of lattice gauge theories. This allows current spin foam models to be defined on arbitrary two–complexes as well as to generalize current spin foam models to arbitrary, in particular finite groups. The similarity with standard lattice gauge theories allows to apply standard coarse graining methods , which for finite groups can now be easily considered numerically. We will summarize other holonomy and spin network formulations of spin foams and group field theories and explain how the different representations arise through variable transformations in the partition function. A companion paper will provide a description of boundary Hilbert spaces as well as a canonical dynamic encoded in transfer operators.
==endquote==

 

[AndyW]

Dear forum members,

I would highly recommend listening to Frank Hellmann's talk on the reformulation of LQG led by Bianca Dittrich. The slides provide a clear and concise overview of the research and the accompanying audio allows for a more in-depth understanding of the topic.

The talk discusses three papers, one of which has already appeared on Arxiv and the other two are expected to be released soon. These papers offer a new holonomy formulation for spin foams, allowing for the extension of the theory space of lattice gauge theories and generalizing current spin foam models to arbitrary groups.

I find this research particularly exciting as it offers new possibilities for numerical simulations and a deeper understanding of the theory. I encourage anyone interested in LQG to check out these papers and the ILQGS series of talks for more information.

It's also worth noting that several of the authors involved in this research are members of the Physics Forums community, including Hellmann, Vidotto, Corichi, and Livine. This serves as a testament to the value of online communities in promoting scientific discussions and collaborations.

Thank you for sharing this information and I look forward to discussing this topic further with anyone who is interested.