Re: [Brahms-dev-l] deuteron paper

From: Peter Christiansen <peter.christiansen_at_hep.lu.se>
Date: Sat, 20 Mar 2010 15:43:13 +0100
Here are some quick comments since I am already late (but I am also not
an author I realize now:-).

The paper reads very well and the data are looks 99% great.

last %: Figure 3. Lower left. I would remove the two open d points as
the enormous error bar IMO distorts the picture.

There might be some errors in the following logic.

I am not sure that I understand the discussion of the chemical potential
at the bottom of page 5. 
Are we sure that we are comparing apples to apples when we compare the
chemical potentials of our fit and statistical models? Statistical
models have long decay chains from initial hadron distributions to final
hadron distributions. So we should compare our fit value to the
"effective" proton chemical potential. I do not know if that differs
from the baryon potential?
Secondly I assume that out p-bar/p agrees with the statistical model. I
would then naively guess that d-bar/d~(p-bar/p)**2 if the chemical
potential is the same. In that way we can directly compare if our
p-bar/p chemical potential and d-bar/d are the same. (Or am I wrong?)

I think it is a very interesting result that the volume of homogeneity
does not depend on rapidity. Here are some thoughts on this.
 
"volume of homogeneity" is sort of "volume" over "flow" 
Our blast wave analysis has shown us that the flow IS rapidity
dependent. 
The initial volume is the same at all rapidities (it is just defined by
the collision geometry) so the initial phase space density is not the
same! 
This implies that the evolution - presumably hydrodynamics - exactly
generates enough flow that in the end the volume of homogeneity (aparent
(?) phase space density) is exactly the same!

If one really wants to push it one could ask what would happen in hydro
if we let it freeze out later i.e. at 10 MeV. Would we then
overcompensate? i.e. is this seen from hydro some miraculous tuning or
just an asymptotic limit that is quickly approached.

Cheers,
   Peter

On Mon, 2010-03-15 at 16:57 -0400, Ramiro Debbe wrote:
> Dear Collaborators,
> On behalf of the authors of the dpAuAu paper please find here the latest version that comes out of several rounds of checks of data and text. Please give us your comments before the end of next week.
> Thanks
> 
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> Brahms-dev-l_at_lists.bnl.gov
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-- 
Peter Christiansen
Email: peter.christiansen_at_hep.lu.se
Phone: (+46) 046-2227709

Address:
Lund University
Department of Physics
Div. of Experimental High-Energy Physics
Box 118
SE-221 00 Lund
Sweden


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Received on Sat Mar 20 2010 - 12:24:21 EDT

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