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Hi everybody,
let me allso add my comments concerning the draft by Berndt and Peter.

General remark: Except for the first paragraph I found this draft a very
carefully formulated document.  I read to read it twice to catch
most of  the disclaimers!
As already mentioned by others, elliptic flow
should be added. Also the possibility and importance of meassuring
open charm should be stressed in the final section.



1) First paragraph. These are many "very optimistic" statements which do not
really find support in the subsequent paragraphs. I certainly would
find it rather difficult to defend some of these statements to any of our
colleagues outside of heavy ion physics.

In particular, I must have missed what the experimental
"breakthroughs" are supposed to be. If there are any, the subsequent
text should clearly spell them out (assuming that most of us can agree
with them).


2) J/Psi suppression:
Most of what I have to say to this subject has already been stated by
other people. Certainly, it is hard to postulate a threshold behaviour
based on what we saw at Charmonix (min. bias data).
The wording of this paragraph takes this into account in a very elegant way.

I would, however, be a little more cautious concerning the expectation of a
threshold behaviour. The sentence "Such a behaviour is expected if the QCD
transition occurs within the covered E_T range" could haunt us in the future.
I am not sure if this statement is unambiguously established. Quite to the
contrary, even in an ideal QGP at a Temperature below the dissociation
temperature of the J/Psi thermal gluons will be efficient to destroy the
J/Psi. And this is certainly a smooth effect, which depends on the lifetime of
the QGP phase and on the thermal distribution.
Furthermore, Satz and Nardi recently used a percolation description of
overlapping strings in order to generate a threshold effect. While this is
an original idea, it is certainly not derived from QCD.
In conclusion, I would be very careful about the above statement. It may
haunt us in the future, in the sense that any "real" claim that we have
discovered the QGP will be ignored by the outside world, because we have not
been able to establish the "predicted" threshold behaviour.



3) Low mass dileptons:
This paragraph is very carefully formulated and it avoids to mention the rather
uncertain experimental situation. In view of the purpose of this document,
this might be the right approach.

The discussion about the (non)relation between changing vector meson
masses and chiral restoration has been pointed out in the literature
many times. I am not sure if the present document is the right place
to reiterate that again.


Let me add a few remarks concerning the low mass dileptons,
although I feel this discussion should be delegated to a topical workshop.

First of all let's not forget, that  the experimental
situation is not yet clear. On the one hand there is the problem with the
background. While arguments have  been given that the observed signal is not
just a misinterpretation of the background I am not sure if all doubts have
been erased.
The argument concerning the shape really hangs only on one
single data point, that at the rho/omega mass. Given the differences
between the 95 and 96 data sets (and the S+Au for that matter), I think it is
too early to conclude anything before we see the new data with the high mass
resolution.  In this sense NA45 is on the right track.

Also, the number of omega-mesons produced in these collisions is not very well
constrained by other data. Reducing the number of omegas in the cocktail
affects the shape of the enhancement towards that of pion annihilation. Again,
this will (hopefully) be resolved with the new NA45 setup.

Let me next address the issue of the contribution from quark - antiquark
annihilation. This point has been raised by J. Wambach in is presentation and
also by quite a few people during the coffee breaks. Shuryaks remarks also
point in this direction.
First of all: There have been numerous calculations which have taken this
channnel into account. Most recently, there was the very systematic study of
Sollfrank et al (nucl-th/9607029). All these calculations conclude that the
contribution of free quarks is  sub-leading (about a factor of 20 below the
data in the aforementioned reference).
Second: Let us assume for the moment that the scenario put forward in the
"hadron thermometry" section is correct, namely that chemical freeze out
happens at a considerably higher temperature that thermal freeze out.
This of course tells us that the hadrons (in particular the pions) still
reinteract after they are being formed. Consequently there HAS to be pion
annihilation! What the shape of this is, is still under debate, but the
integrated yield in most calculations is compatible with the enhancement
reported from the '96 data.

Finally let me add a comment  to J. Wambachs remarks. Measuring the
vector-correlator is important, no doubt. But let me emphasise that dilepton
pairs carry only HALF the signal for chiral restoration. The other half is the
axial correlator, which is probably very hard to get to in experiment.


4) Hadron thermometry. From the work of Beccatini we know that the
relative ratio between the particle abundances are essentially driven
by phase space dominance in the reaction. This is of course not what
we would call chemical equilibrium, namely the vanishing of the Boltzmann
collision integrals. Therefore, the "temperature" extracted from the chemical
analysis is not necessarily the temperature one would put on the QCD phase
diagram. In order to identify these temperatures the existence of thermal
equilibrium needs to be established. Maybe event-by event physics will help.

I agree with R. Stock that the issue of the J/Psi transverse momentum slope
should go in section one.


Volker Koch