What is the Excitement in AdS/QFT Model Building?

[selfAdjoint]

arivero has http://www.physcomments.org/node/444" the considerable interest the physics community is showing into the new, or revived, field of Ads/QFT model building. It is somewhat similar to Lisa Randall's style of model building, described in her new book Warped Passages, which I recommend.

arivero only mentions by name one of the papers fueling the excitement, but I followed it up on the arxiv; it's hep-ph/0501128,

QCD and Holographic Model of Hadrons

By Joshua Erlich, Emanuel Katz, Dam T. Son, and Mikhail A. Stephanov

From the Abstract

We propose a five-dimensional framework for modeling low-energy properties of QCD. In the simplest three parameter model we compute masses, decay rates and couplings of the lightest mesons.
The model fits experimental data to within 10%. The framework is a holographic version of the QCD sum rules, motivated by the anti-de Sitter/conformal field theory (AdS/CFT) correspondence. The model naturally incorporates properties of QCD dictated by chiral symmetry, which we demonstrate by deriving the Gell-Mann–Oakes–Renner relationship for the pion mass.

From the introduction

Inspired by the gravity/gauge duality we propose the
following complementary approach. Rather than deform
the SYM theory to obtain QCD [5], we start from QCD
and attempt to construct its five-dimensional (5D) holo-
graphic dual. In this Letter, we present an exploratory
study of a simple holographic model of QCD. The field
content of the 5D theory is chosen to reproduce holo-
graphically the dynamics of chiral symmetry breaking in
QCD, the boundary theory. The model has four free pa-
rameters, one of which is fixed by the number of colors;
the remaining three parameters can be fitted using three
well-measured observables, e.g., the ρ meson mass, the
pion mass, and the pion decay constant. The model then
predicts other low-energy hadronic observables with sur-
prisingly good accuracy.

From the Discussion and Outlook

The holographic model of
QCD studied here is quite crude and depends on only
three free parameters, but it agrees surprisingly well with
the seven experimentally measured observables which we
have studied.

One of the things I liked about this model is that it doesn't require supersymmetry; it just does QCD as we know it (slightly simplified). Do go and look at their tables of fits. Of course the point is not that they can tune a model to fit the data; it is that THIS model, though parsimonious, can be so tuned. It deserves the excited attention it is getting!

 

[josh1]

Well, ads/cft is an actual quantum theory of gravity. This isn't always appreciated in this forum. What these guys are doing has nothing to do with gravity. Inspired by the general idea of ads/cft holography, they are simply trying to construct a holographic dual of qcd.

 

[selfAdjoint]

Inspired by the general idea of ads/cft holography, they are simply trying to construct a holographic dual of qcd.

Quite so. And while I believe there are several stringy/brainy approaches to supersymmetric extensions of the Standard Model, this is the first one I've seen that tries to do even part of the model (QCD) is it stands. To me, that's news.

LQG people apparently feel kinder toward AdS/CFT than to other string initiatives; perhaps some rapprochement is in the works.

 

[arivero]

Inspired by the general idea of ads/cft holography, they are simply trying to construct a holographic dual of qcd.

I'd not say "simply". Even if their results are not reusable for a theory of emergent gravity -and who knows?- it can be a good test ground for the PhysMath created for/by string minded people.

 

[arivero]

arivero only mentions by name one of the papers fueling the excitement, but I followed it up on the arxiv; it's hep-ph/0501128,

QCD and Holographic Model of Hadrons

By Joshua Erlich, Emanuel Katz, Dam T. Son, and Mikhail A. Stephanov

It is funny that it is a 0501 but it took all the year to cross the PhysRevLetters Caronte's river, so when published it had already accumulated a good bunch of quotations!

Another one I found in the network is from M Shifman, a high level senior, from talks delivered last summer; it is hep-ph/0507246

In a next entry to Physcomments I also linked to the Nature article about the fuzz, but I ack it is subscrition only. Let me copy paste the references from it:

# Erlich, J. , Katz, E. , Son, D. T. & Stephanov, M. A. Phys. Rev. Lett. 95, 261602 (2005).
# Da Rold, R. & Pomarol, A. Nucl. Phys. B 721, 79–97 (2005).
# Maldacena, J. M. Adv. Theor. Math. Phys. 2, 231–252 (1998).
# Babington, J. , Erdmenger, J. , Evans, N. J. , Guralnik, Z. & Kirsch, I. Phys. Rev. D 69, 066007 (2004).
# Son, D. T. & Starinets, A. O. hep-th/0601157 (2006).

 

[marcus]

It is funny that it is a 0501 but it took all the year to cross the PhysRevLetters Caronte's river, so when published it had already accumulated a good bunch of quotations!

Another one I found in the network is from M Shifman, a high level senior, from talks delivered last summer; it is hep-ph/0507246

In a next entry to Physcomments I also linked to the Nature article about the fuzz, but I ack it is subscrition only. Let me copy paste the references from it:

some say that the river of AIP peer-review you refer to is the STYX
I believe most would agree that the boatman who takes departed souls across this river is named Charon
http://www.pantheon.org/articles/c/charon.html
although you may prefer to call him Caronte

another name for the river is Acheron
http://www.pantheon.org/articles/a/acheron.html
which means "river of woe"

there is another minor linguistic matter:

but I ack it is subscription only

Does this refer to a smiley symbol of chagrin called ACK?

the emoticon symbols are, for us, what the Greek gods and godesses were for the poets of the 16th Century. Or rather, the classical gods and godesses were the emoticons of that day.

If it exists, the chagrin emoticon : ACK : would be related to the symbol of surprise and horror : EEK : written this way

and also to the emblem of disgust : YUCK : written :yuck:

 

[arivero]

but I ack it is subscription only

Does this refer to a smiley symbol of chagrin called ACK?

the emoticon symbols are, for us, what the Greek gods and godesses were for the poets of the 16th Century.

I am sorry here I am not so modern as to think according emoticons :uhh: , so that my ack comes from electronics board designs, its primitive meaning being "protocol acknowledge signal". It is from the pre-sms age, as for instance "cu" for "see you".

 

[selfAdjoint]

]quote]another name for the river is Acheron [/quote]

I dimly recall that four rivers watered Hades; the Styx, the Acheron, the Lethe, and one other that I can't remember.

 

[marcus]

another name for the river is Acheron

I dimly recall that four rivers watered Hades; the Styx, the Acheron, the Lethe, and one other that I can't remember.

I ack that Acheron is not the same river as Styx

 

[selfAdjoint]

I ack that Acheron is not the same river as Styx

My memory was short one river; Wiki says:

The five rivers of Hades are Acheron, Cocytus, Phlegethon, Lethe and Styx.

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