Gluon propagator in the infrared

[Lester]

I have read some recent preprints in arxiv recently:

http://arxiv.org/abs/0709.2042

http://arxiv.org/abs/0704.3260

http://arxiv.org/abs/hep-th/0610148

about the behavior of the gluon propagator in the infrared. Recent lattice computations seem to support them (e.g. http://arxiv.org/abs/0710.0412) and the agreement with the spectrum of a pure Yang-Mills theory appears quite striking (e.g. http://arxiv.org/abs/hep-lat/0404008) with a proper choice of the string tension. I was not able to find any obvious fault in the mathematical derivations in these papers. In other times such a very good coincidences with the known results should have excited the community or some rumors should have been going around. Nothing of this happened. So, why?

Lester

 

[mormonator_rm]

I have read some recent preprints in arxiv recently:

http://arxiv.org/abs/0709.2042

http://arxiv.org/abs/0704.3260

http://arxiv.org/abs/hep-th/0610148

about the behavior of the gluon propagator in the infrared. Recent lattice computations seem to support them (e.g. http://arxiv.org/abs/0710.0412) and the agreement with the spectrum of a pure Yang-Mills theory appears quite striking (e.g. http://arxiv.org/abs/hep-lat/0404008) with a proper choice of the string tension. I was not able to find any obvious fault in the mathematical derivations in these papers. In other times such a very good coincidences with the known results should have excited the community or some rumors should have been going around. Nothing of this happened. So, why?

Lester

Hmmm...

First of all, I think these first three papers listed are all slightly different presentations of the same work, and have been posted by the same author. I am not familiar with Marco Frasca, and I am not sure of his affiliation.

I would be more excited about these papers if they were supported by physical experiments, rather than just the fact that they fit well with recent lattice work. Also, I do not personally agree with his idea of the sigma meson being linked so heavily to the glueball masses; it is as if he is saying that the sigma is a sort of "super-light glueball". If that was true, then we would also see a super-light tensor resonance around 1000 to 1050 MeV, according to his same work. This resonance has never been seen, to my knowledge, and if it was seen it was certainly never confirmed. I think a tetraquark-meson mixing model is a much more plausible explanation of the sigma resonance than this.

Furthermore, he is taking all of this in the "infrared limit", which assumes the energy of an individual gluon is very small. Certainly this is his target region, but I cannot see this working well in the relativistic world of light-quark hadrons and glueballs. Maybe it would be okay for extremely massive quarks, but I do not know. I am no expert at this, either, so I hope someone who really knows this stuff comes along to comment.