[Brahms-l] Re: Whitepaper/ sQGP

Dear Michael,

your deductions summarize our discussion at the collaboration
meeting in Oslo succinctly. Why do you not embellish on your 4 points? 
This would nicely fit into our second chapter.

With best wishes,
Dieter


On Wed, 2 Jun 2004, Murray, Michael J wrote:

>       Dear Jens Jorgen,
>            thanks for all your work. You are correct that the key question is weather we have observed deconfinement but the introduction of the white paper does not address the question that we have been asked. That is have we produced a strongly interacting QGP, sQGP. This (like Frankenstein) is quite a different beast from the simple system than we dreamed of creating 20 years ago. We do have a high energy density but unfortunately the temperature goes as (energy density)^1/4. At temperatures of 2-3*Tc it seems that QCD does not behave as an ideal gas of quarks and gluons but rather as a seething mass of correlated gluons, quarks and diquarks. The importance of deconfinement is that these objects are COLORED.
> 
> 
> Starting from this viewpoint theorist seem to be making the following deductions. 
>  
> 1) The coupling between these objects is very strong.
> (Lattice calculations say that we should have an energy density that is
> 85% of the Stephan Boltzman limit for weakly interacting system. This seems pretty good. However supersymetry calculations say that if the coupling constant is infinitely strong then the energy density would be 75% of the Stephan Boltzman limit.)
> 
> 
> The strong coupling  accounts for why such a small system behaves like a perfect liquid. Shuryak pointed out that a drop of 1000 water molecules would never flow but that 1000 gluons do. The flow of quarks implies that
> V2/n_quark vs Pt/n_quark is the same for baryons and mesons. The baryon over pion excess at intermediate Pt may be due to fast quarks from jets recombining with slow thermal quarks from the bulk.
> 
> 2) Thermalisation and entropy production occurs early
> 
> The only way to get such a large V2 is to have a very early thermalisation.
> This is because the pressure gradients caused by the initial anisotropy are quickly washed out by expansion. (This is why they seem to like the colored
> glass scenario since it creates lots of entropy very fast). 
> 
> 3) Jets lose energy moving through this plasma of colored objects.
> The case for this seems very strong.
> 
> 
> 4) Chemical Freeze-out seems to be consistent with a statical sampling of
> quarks. (Quark coalescence seems to be necessary to explain the p/pi ratios.) 
> 
> 
> These points may not be a correct but they are my impression of the theorists case for the sQGP. I think that we should describe this beast and then see if we can recognize him in our data.
> 
> Michael 
> 
> 
> 
> 

-- 
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Dieter Roehrich                   |
Institutt for fysikk og teknologi | Email: Dieter.Rohrich@ift.uib.no 
Universitetet i Bergen            |               Tel: +47-555-82722 
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