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Hi everybody,

This is a write-up of some physics points discussed in Chamonix,
which may be useful for the report and later discussion
about the future of the SPS program. I tried to write them up 
in a compact form.

1. There was a very detailed and interesting discussion of all dilepton
experiments (of which I am  a long-term fan), but the achievements
and prospects of hadronic ones came later in the day and were not defined
as sharply as they deserve. I think those also belong to
``achievements" section, in some form.

Large acceptance of NA49 has allowed new things which was not done
before. On top of spectra and HBT, which revealed large radial flow,
two new elements emerged:
 (i) all kind
of things related to phi asymmetries, especially rather large elliptic flow;
(ii) findings that several observable event-by-event fluctuations look as very
 regular Gaussian, at least for about 2-3 orders of magnitude measured. 

The former is not new in general, but new to the SPS energy domain. It is 
small and not so easy to find, but it is a very
instrumental tool to study EARLY SOS, which is one of the central issues
of the whole program since it may reveal connection to QCD phase transition.
It shows that SOS is definitely VERY SOFT at early stages at SPS because
asymmetries are only several percents. (As compared to say 30% from 
Ollitrault calculations for a simple EOS) It is still about twice what 
RQMD and several times what VENUS predict: so these string-based models 
are WAY TOO SOFT in terms of early transverse pressure.

The latter is new, and is a big blow to searches for all kind of unusual 
events, as well as to claims that small number of particles and
non-equilibrium effects of all kind would invalidate deterministic approaches
based on entropy and thermodynamics.

2. About future program. If the NA50 anomaly survives next run, with its
simplified target arrangement (by the way it was not mentioned in Chamonix,
I asked Gonin later and he told me about modifications - I think it is a
very good step), then the issue of correlation of their signal to other 
observable would be instrumental, to understand its relation to QGP and the
phase transition. Let me try to make this point as simple as possible.

Which hadronic observable may show the change of behavior at b about 8 fm
in PbPb (or other conditions with similar energy density)?

If at this point there is a sudden jump into QGP phase (as Dima and Helmut
advocated a couple of years ago, based on bubble formation), then ALL OF THEM
including enropy (=multiplicity) should show  change.

If (as proposed by D.Teaney and myself in recent paper in PLB) J/psi 
suppression is related to the END of the transition  (the ``softest point" 
of EOS), then one should see a change of behaviour in ELLIPTIC FLOW,
 a beginning of the rise to be continued at RHIC/LHC. (MAYBE WE ALREADY
see the beginning of rise due to pressure of QGP at early time?) 

If (as proposed by Blaizot/Ollitrault paper and essentially 
discussed by Helmut at Chamonix)
we just find a dissolution of chi's, at some critical density, then one should
hardly  expect any hadronic observable to react at this point.

3.Practical arrangements are to be discussed by spokesmen of course, but 
let me inject one more point here. Helmut suggested AB about 10000 (as SnSn)
as a step back, in which the suspicious energy density would be at mid-ET.
Let me point out that in this case b is about R, which is 
also the best geometry for elliptic flow measurements.
Another option is to keep PbPb, but step down in energy to
about 100 GeV, in between 40 GeV (where such conditions are at b=0) and 160.

4. Qualitatively new goal for the SPS program may be a search for a tricritical
point (or rather the endpoint of 1-st order transition). It was suggested by
Stephanov, Rajagopal and myself recently, and had some resonance among 
theorists (see e.g. Wilczek's letter in the last Nature).

 HOW to search was discussed in our paper, but maybe much
better ways would be found later. 
The bottom line is it is THE ONLY really singular point on the phase diagram,
where one mode is truly massless. The heat capacity is truly infinite, so
one should find a very counterintuitive observations such as:  mean Pt
(or temperature) fluctuations are nearly absent, or at least significantly
 less than what random statistics predicts. It would be spectacular to
find it!

WHERE is it? (Very model dependent and not reliable)
 estimates done in the mean field approximation.
lead to the region in the ballpark of  the 40 GeV point. 
It is not clear how much help a look at ET dependence would provide, 
but we may still be  lucky and find it, if it exists and is down from 40.

There is a lot of scepticism about thermodynamical motivations here: but 
this is a story similar to the endpoint searh of the gas-liquid transition
 in nuclear matter. Whatever some people may think about it,
 the peak in multifragmentation  was indeed found.