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I've heard the claim that some aspects of string theory are used to improve Monte-Carlo simulations of lattice QCD, for example by people working at the LHC. I know a bit about Monte-Carlo methods in lattice QCD, but have no idea of how string theory ideas are applied to QCD at all, so I'd like to ask for

  • a short explanation of how and why string theory ideas are applied to QCD in general and

  • how they can be used in Monte-Carlo simulations of lattice QCD in particular.

References are welcome, too, of course. Maybe I should have looked for them myself, but I'm sure I'll get some useful recommendations much faster this way :-)

Edit: Let's narrow the question down to: How can ideas in string theory be used to improve Monte-Carlo simulations of lattice QCD? (Lattice QCD is to be understood in the sense of strict SM without any ideas beyond the SM like supersymmetry, Ads/Cft etc.)

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Tim, I am afraid you may be conflating several issues. There are of course many ways in which string theory is relevant and used for QCD, lattice QCD, etc., in particular AdS/QCD based on AdS/CFT; twistor calculations of QCD scattering amplitudes; better models of lattices for supersymmetry and fermions based on deconstruction that may be derived from string theory; and perhaps others that I missed. Most of these are "inspired" by string theory but they're not "hardcore string theory". It is not obvious to me that your question is asking about a review of all of them, or a specific one... –  Luboš Motl Feb 4 '11 at 9:07
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Ok, I'll try to narrow the question to be just about improving Monte-Carlo simulations of lattice QCD models, is that precise enough? –  Tim van Beek Feb 4 '11 at 9:18
    
It seems precise enough. I just don't seem to be familiar with the material you want. –  Luboš Motl Feb 4 '11 at 10:23
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I'm afraid the answer is that anonymous posters on blogs are not the most reliable source of information. –  pho Feb 4 '11 at 18:12
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If you could link to some of those anonymous blog comments, some of us might be able to figure out what they're referring to or whether they're just nonsense.... (I've written enough anonymous blog comments not to reject them all out-of-hand, but you have to sort the wheat from the chaff.) –  Matt Reece Feb 5 '11 at 4:18
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1 Answer

up vote 4 down vote accepted

I don't know that much about lattice QCD, but I do know a few things about string theory and the gauge/string duality approach to QCD. I'm pretty sure the answer to your question is that ideas in string theory have not been used to improve Monte-Carlo simulations of QCD. Unified versions of string theory can't since they involve physics much above the QCD scale. Gauge/string duality models are still too crude, typically giving answers that are sometimes accurate to 15% but not in a well controlled approximation. The only way that I can see there being a smidgen of truth to the claim about using string ideas to improve lattice QCD is through the renormalization group improvement of lattice actions for QCD, an idea which I believe goes back to Symanzik. If you google "lattice QCD renormalization group improvement" you will find a number of reviews. Some ideas from string theory have improved our ability to do perturbative QCD calculations, and the RG improvement techniques are based on perturbative calculations, so it is just possible that this is the link that was mentioned to you. However I am not aware of this actually being the case, that is of a calculation of an RG improved lattice action that required new techniques from string theory in order to do the perturbative QCD calculations.

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How about this preprint arxiv.org/PS_cache/arxiv/pdf/0802/0802.0514v1.pdf "The AdS/CFT correspondence between string theory in AdS space and conformal field theories in physical space-time leads to an analytic, semi-classical model for strongly-coupled QCD which has scale invariance and dimensional counting at short distances and color confinement at large distances." –  anna v Feb 5 '11 at 5:11
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