Comments on: 291. Chiral symmetry breaking in soft wall AdS/QCD model

By: wei

wei — Mon, 11 Jan 2010 09:07:43 +0000

I have learned a lot from your post and your explanation. Thank you.

By: Tom Kelley

Tom Kelley — Tue, 05 Jan 2010 16:39:23 +0000

I agree with you that the f_0 radial excitation spectrum is not fully understood yet, I chose the resonances after evaluating available literature, but still there are a lot of uncertainties. I see now the issue with ssbar; it may be a good think to look into incorporating the ssbar component.

By: wei

wei — Tue, 05 Jan 2010 09:25:48 +0000

Thank you for your response.
You are right, one must fit the isosinglet mesons f_0.
But since there is not heavier quark such as strange quark, in the fitting procedure one can not pick up the mesons made of ssbar. Right?
In the fitting procedure, the first two scalar mesons are f_0(550)(also refered as sigma) and f_0(980). Although their nature is still on the debate, they could be identified as the mixture of qqbar and ssbar and they have the same principle number (n). It is also similar for the other mesons. So in my opinion, the mesons which are composed of the strange quarks (many people use this kind of spectrum) are inappropriately used.
Thank you again.

By: Tom Kelley

Tom Kelley — Mon, 04 Jan 2010 21:47:29 +0000

Thank you for your comment. I would have responded earlier but I have been away during the winter break. As for your questions,
1. Both 5-d actions are correct, the sign differences arise from our respective choices of metric signature (-++++) or (+—-).
2. You’re right that this is very much a light quark model which doesn’t necessitate heavier quarks, however, I do not believe that should affect the scalar fitting. If this is a problem I would suspect it would affect the scalar couplings to the vector/axial sectors.
Also, since the scalar field is dual to , the described particle must take the corresponding quantum numbers, which are those of f_0.

By: wei

wei — Sun, 20 Dec 2009 17:58:56 +0000

Thank you for the nice post.
I really hope I could read it earlier, but I do have a couple of questions about your post and your paper.
1. In the 5-d action, it seems that the second term including the bulk field have a different sign with the one in hep-ph/0501128.
2. I don’t think you have included 3 flavors in the 5-d action and thus your fitting of scalar spectrum is quesionable. In the spectroscopy study, the isospin-1 scalar mesons (a_0, like rho and a_1) are more suitable than isospin-0 mesons f_0 as you used.

By: 305. First two weeks of March on NEQNET

305. First two weeks of March on NEQNET — Sat, 14 Mar 2009 20:34:10 +0000

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