The following is not particularly brief and somewhat of a core dump. I
have tried to divide things into three main sections.

\(1\) The issue of the definition of the quark-gluon plasma,

\(2\) The list of PHENIX published results and my current understanding

(I tried to use Mike Tannenbaum\'s numbering convention),

\(3\) Some general remarks on the drafting of the white paper.

Sincerely,

Jamie

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

\(1\) PLASMA DEFINITION SECTION:

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

Although in an ideal world (see Feynman\'s article Cargo Cult Science)
we might be able to ignore this issue, the term is a landmark in our
field despite the lack of any clear definition. I liked Paul\'s
different levels of quark-gluon plasma, but I believe that if one cannot
be concise, one can come across as too lawyerly. I note that the
post-CERN press release discussion of quark-gluon matter versus
quark-gluon plasma made me want to quit the field.

I think we need to be careful not to just repeat the mantra of the field
without further clarification.

Having never taken a plasma physics course or research project, I
decided to do some reading and had a few conversations with the plasma
researchers at the University of Colorado. Below I include some
interesting quotes from three relatively introductory books on the
subject. All the quotes are enclosed by \"=====\" marks so you can skip
them if desired.

================================================================================

================================================================================

\"Introduction to Plasma Physics\", R.J. Goldston and P.H. Rutherford

\"What is a plasma? First and foremost, a plasma is an ionized gas. When
a gas is heated enough that the atoms collide with each other and knock
their electrons off in the process, a plasma in formed: the so-called
\'fourth state of matter.\' Exactly when the transition between a \'very
weakly ionized gas\' and a \'plasma\' occurs is largely a matter of
nomenclature. The important point is that an ionized gas has unique
properties. In most materials the dynamics of motion are determined by
forces between near-neighbor regions of the material. In a plasma,
charge separation between ions and electrons gives rise to electric
fields, and charged particle flow give rise to currents and magnetic
fields. These fields result in \'action at a distance\' and a range of
phenomena of startling complexity.\"

\"Maxwell-Boltzmann statistics arise repeatedly in plasma physics, and
the next example (Debye Shielding) is fundamental to the very definition
of a plasma.\"

\-\-\--

\"Basic Principles of Plasma Physics: A Statistical Approach\", S.
Ichimaru

\"Plasma physics is concerned with the equilibrium and non-equilibrium
properties of a statistical system containing many charged particles.
The forces of interaction betweeen the particles are electromagnetic,
extending themselves over wide ranges. The system is characterized by an
enormous number of microscopic degrees of freedom arising from the
motion of individual paticles.\"

\"A plasma may be defined as any statistical system containing mobile
charged particles. Vague as it may sound, the foregoing statement is
sufficient to define what is known as plasma in physics and
engineering.\"

\"A plasma is a collection of charged particles. The Coulomb force with
which the charged particles interact is well know to be a long-range
force. As a consequence, the physical properties of a plasma exhibit
remarkable differences from those of an ordinary gas.\"

\"The Debye length and plasma frequency are the basic quantities
characterizing a classical plasma.\"

\-\-\--

\"Introduction to Plasma Physics and Controlled Fusion: Volume I: Plasma
Physics\", F.F. Chen

\"Definition of Plasma: Any ionized gas cannot be called a plasma, of
course; there is always some small degree of ionization in any gas. A
useful definition is as follows: A plasma is a quasineutral gas of
charged and neutral particles which exhibits collective behavior.\"

\"In an ordinary gas \... since the molecule is neutral, there is no net
electromagnetic force on it. The molecule moves undisturbed until it
makes a collision with another molecule, and these collisions control
the particle\'s motion. The situation is totally different in a plasma,
which has charged particles. As these chargeds move around, they can
generate local concentrations of positive and negative charge, which
give rise to electric fields. Motion of charges also generates currents,
and hence magnetic fields. These fields affect the motion of other
charged particles far away.\"

\"A fundamental characteristic of the behavior of a plasma is its
ability to shiled out electric potentials that are applied to it \[Debye
shileding\].\"

\"Criteria for Plasmas: A third condition \[for a plasma\] has to do
with collisions. The weakly ionized gas in a jet exhaust, for example,
does not qualify as a plasma because the charged particles collide so
frequently with neutral atoms that their motion is controlled by
ordinary hydrodynamics forces rather than by electromagnetic forces. If
w is the frequency of typical plasma oscillations and t is the mean time
between collisions with neutral atoms, we require wt \> 1 for the gas to
behave like a plasma rather than a neutral gas.\"

================================================================================

================================================================================

The clearest thing to me is that we are not creating a plasma. A plasma
is an ionized gas of electrically charged particles. The key
characteristics seem to be the long-range Coulomb force giving rise to
interesting electric and magnetic fields that dominate the described
motion. Debye screening due to mobile electric charges is another key
characteristic. Notice that no one requires equilibration in their
definition. In fact, the electrons and ions are often not in
equilibrium.

What we might be creating is an object of particles interacting
dominantly via the strong force that is a \"good\" analog of the
traditional plasma (as defined above). It is a good analog in the
simplest possible sense. In a gas of atoms, the electric charges are
paired, thus suppressing electromagnetic interactions (down to dipole
moments etc.) and allowing atomic collisions to dominate the dynamics.
In nuclear matter quarks/gluons are grouped into color singlet hadrons,
thus suppressing strong interactions (down to residual pion exchange).
If one frees the quarks and gluons, there is a basic analogy to ionizing
a gas.

It seems that this may be the end of the analogy. Since the strong force
is not long range, much of the key behavour of plasmas due to long-range
Coulomb interactions (important electric and magnetic fields) do not
apply in the same way. Do we expect large scale color separation in the
QGP giving rise to large color electric and magnetic fields? There is a
paper by B.Mueller on color chaos, but I do not remember the key points.

In my mind, given the above definitions of a traditional plasma, it is
up to us to define the quark-gluon plasma and make clear it is only a
very limited analog of the traditional plasma. In addition, one key in
the definitions below, is that \"new\" and \"unique\" behavours are
observed that distinguish a gas from a plasma. We need to define what
are the QGP\'s unique characteristics.

This reminds me of color glass condensate (CGC). Originally Larry
McLerran coined this phrase because he thought it had properties of the
spin glass. Then when that turned out not to be true, the analog had to
do with the separation of time scales in the evolution of glass
materials. This is a little dangerous, but the point is that CGC is not
a glass. If one can identify the key property that is analogous and make
that clear, that is sufficient for the analogy.

One other note, many people want to say you have to have \"free\" quarks
and gluons, quarks and gluons as the fundamental degrees of freedom,
liberated quarks and gluons. At high enough temperatures (much higher
than what we achieve at RHIC), the partons will achieve asymptotic
freedom (which is a well defined type of freedom). In this case, it
seems clear that one has a \"weakly\" strong-force interacting gas of
quarks and gluons. It also seems clear that one had this form of matter
in the early universe far before one got anywhere near what we label as
the phase boundary to hadronic matter. In some ways, I like this
definition of a quark-gluon plasma. Unique characteristics from our
\"hadron-gas\".

However, this definition automatically means we do not create
quark-gluon plasma at RHIC (or LHC for that matter). This does not
really bother me. Perhaps there is another type of partonic plasma
created at RHIC. Remember that in a traditional plasma, the
quasi-particles need not be single electrons and ions. Many electrons
can form bizarre configurations (fractional quantum hall effect as a
solid state example). That may well be what we have at RHIC (other
quasi-particles composed of quarks and gluons, but not free vacuum
hadrons), though I think we do not have sufficient experimental evidence
of this to date. If the new quasi-particles are really just the same as
hadrons but with modified spectral functions, that does not sound like a
good plasma analogy.

My other example/question here is if a partonic-plasma is simply a new
form of matter characterized by new combinations of partons (not
hadrons), then the color superconducting matter at high density, low
temperature is a partonic-plasma of sorts. The place where it breaks
down is if you want it to have long range electric and magnetic fields,
then that does not work so well (but also not for our QGP either).

I am leaning towards the idea of defining the QGP as the asymptotically
free limit which we do not make, and defining a new partonic-plasma
phase at RHIC (yet to be confirmed experimentally). We know it is not a
hadron gas, and not a QGP, so some other state.

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

\(2\) PHENIX PUBLICATIONS AND WHAT THEY MEAN?

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

Here I have used the numbering from Mike Tannenbaum\'s email (perhaps
that will help).

\[1\] Multiplicity and ET at mid-rapidity

Not much to add relative to Mike.

One point is that if we quote the Bjorken energy density, we should
discuss how to put a systematic error bar on the point. We always are
asking theorists to do this. Since the Bjorken scaling assumption
strongly disagrees with data from Brahms and Phobos, how much do we
expect this might change the value. Also, I have made a plot which I
often show in talks of Bjorken energy density versus time (with the
characteristic 1/t) drop off for the longitudinally expanding cylinder.
We also need to mention the factor of 2 error in the Bjorken paper. It
should be noted that a well-known theorist used the wrong equation (as
in the paper) at the CERN press release presentation. Some PHENIX people
mentioned at the plenary session discussion, that all models roughly
agree on the energy density. What other models? Is there an energy
density we can extract from a Landau model? The fact that Bjorken
couples spatial slices with momentum (very clever) is what really allows
dET/dy to map onto spatial energy density.

This brings up a basic point (which will be very important in the high
pT suppression discussion), does everyone agree that the energy density
must fall somewhere between 1/t and 1/t\^(4/3)? Most all of our
theoretical calculations we compare to have to do some modeling of the
time evolution. Many use the Bjorken scenario (which we know not to be
correct). Much of our ability to rely on them depends on our agreement
about this fall off. I think Paul mad e the excellent point that the
energy density starts at almost 1 TeV (complete spatial overlap of the
Lorentz contracted nuclei in the CM frame), and then it must fall off
from there.

Even though this white paper is focused on QGP issues, are we also to
discuss CGC. It seems like we need to say something since it contributes
to many of the initial condition arguments. Mike\'s point about CGC and
ET is a good one. In particular they have often argued that longitudinal
work can reduce the ET they calculate (a factor of 3 higher than we
measure). However, they get the pseudorapidity distribution of Nch
correct with Phobos. How can you have lots of longitudinal work and not
move particles around in rapidity. I should note that after I was not so
nice to CGC models at the Quark Matter 2004 student session, Raju made
me aware of an erratum on part of this (hep-ph/0305112).

I think all our early conclusions on scaling of charged particles as
getting at the mix of hard and soft processes (a perfect factorization
ala X.N. Wang in HIJING) were too naive and I would not emphasize that
point.

\[2\] Multiplicity, Charge and \<pt\> Fluctuations

The charge particle ratio fluctuations paper states the extreme result
that we see fluctuations with D \~ 4 (or choose some other variable),
which is expected in a pion gas, and that theory predicts D \~ 0.75 for
a quark-gluon gas. I have been studying this in some detail and chatting
with Tom DeGrand at Colorado and emailing the relevant theorists. I will
post these finding under a different link. My conclusion is that even if
we have a quark-gluon gas with reduced charged particle ratio
fluctuations, and it follows the Bjorken scenario (as used by Jeon and
Koch) such that we measure particles from a single spatial region
(corresponding to rapidity +/-0.35), because our acceptance samples less
than 25% of the pions that finally come out from that region, it
substantially Poissonizes the fluctuations to the same numerical result
as the pion gas limit (D \~ 4). Additionally, even in the theory papers
they quote a number for pion rescattering of sigma-y \~ 0.5 units. This
would have a dramatic Poissonizing of our observed fluctuations. Again,
see this separate note. Even STAR with +/-1 unit of rapidity coverage
and full azimuth (except spokes) only sees a small reduction in the D
value. The STAR balance function result may be the most interesting on
this topic.

The \<pt\> fluctuations, the main conclusion in the latest paper is that
you can have fluctuations due to jets. These fluctuations are then
reduced in agreement with the suppressed high pT observation. The main
conclusion here is that (as with the back-to-back correlations), it
provides evidence that these high pT objects are from jet pairs, and the
suppression is on this level.

\[3\] v2 and HBT

As a small historical reference, at one time people in the field would
show pt spectra and could not dis-entangle \"temperature\" from
transverse velocity \"flow\". One interesting example is the paper
\"Transverse Baryon Flow as Possible Evidence for a Quark-Gluon-Plasma
Phase\", P. Levai and B. Muller, PRL 67, 12 (1991). Note that this paper
is talking about proton-(anti)proton reactions.

Then people (U. Heinz included) worked out that the pT dependence of HBT
radii also gives similar information. Thus, experiments such as NA44 and
others then could separate the T and v parameters.

Now with the very large values of v2 at RHIC, it is realized that you
have another observable that is sensitive to T and velocity flow. This
is the best of situations, where the problem is over-constrained. And
now that hydrodynamic calculations do not agree with HBT when they are
matched with transverse momentum spectra and v2, people want to ignore
the extra constraint.

People have argued that v2 is the most sensitive to the early stages
(and self quenching), transverse flow to later stages, and HBT to the
latest stage. Thus, some people like Miklos would argue that the
disagreement with HBT should not bother us too much. People on the STAR
experiment (see Mike Lisa\'s QM talk) like to show that the blast wave
parameterization of the freeze-out hypersurface can describe all three.
The comment I have heard (not tested myself certainly), is that there is
no hydrodynamics calculation that produces this hypersurface. It would
be nice to confirm this.

The large v2 measured by PHENIX indicate strong collectivity. However,
the key is whether this \"large\" collectivity follows a hydrodynamic
description and/or a description at the microscopic level (parton
cascade). My understanding of the results from Denes Molnar\'s Ph.D.
thesis is that he calculates parton-parton scattering using only the
perturbative cross sections (assuming asymptotic freedom?). I have
always assumed this is a microscopic description of what a \"weakly\"
interacting gas of quarks and gluons would be like. When he finishes the
calculation, he finds that v2 for the partons is much less than what is
measured for the various hadrons. All of my assumptions about this
calculation need to be confirmed.

It is this result that and the agreement of the hadrons (at low pt -
pt\<1 GeV for pions, pt\<2.5 for protons) with hydrodynamic calculations
that leads many people to say we have a \"strongly\" interacting system
as opposed to the \"weakly\" interacting QGP. Note the title of the
proposed Lee/Samios journal issue \"Strongly Coupled QGP\". Shuryak and
others talk about parton-parton correlations or quasi-particles that
imply not \"free\" quarks and gluons, and a much stronger coupling.

One key issue that needs to be resolved involves the recombination
models.

People have found a rough scaling of v2/n versus pt/n where n is the
number of valence quarks. I like Mike\'s comment on this \"Let me only
say on this issue that I think the famous v2/n vs pT/n plot doesn\'t
prove anything.\" One main confusion on my part is that hydrodynamic
calculations do not specific the quasi-particles (they just use an
equation of state). At the end of the calculation, one can map the final
hypersurface onto particles. When you map onto particles as hadrons with
their full vacuum masses, we find reasonable agreement with pi, K, p,
lambda (STAR) v2 data at low pT. The valence quark scaling at higher pT
has led some to say that it shows that the hydrodynamic flow is for the
quarks - hence QGP! (see Fries, Bass, Muller paper). This kind of
comment really confuses me. How can the hydrodynamic fluid map onto free
vacuum mass hadrons at low pT and quarks with constituent masses at
higher pT? In addition, does the scaling with constituent mass imply no
chiral symmetry restoration? If we had only neutral current masses,
wouldn\'t we expect the strange quarks to show a big difference? Charm
v2 will add something to this picture as well, for which Run-4 data
should give us a real measure with statistics.

Denes also now says that if you coalescence the partons, it increases
the v2 for hadrons. Thus, he claimed recently (though not in a paper
that I have found) that this then reconciles his calculation (see above)
with the magnitude of v2 for hadrons. If this is true, do we have the
\"weakly\" interacting QGP? Shuryak disagreed with Denes at QM. I would
like to understand this much better.

One partial explanation I got from Scott Pratt is to imagine
intermediate pT quarks are attached to something else in the medium via
a color string. He claims that these quarks have only a 40% chance to
find an antiquark or diquark partner near in phase space to coalesce
with and form a meson or baryon. If it does not find a partner, the
string stretches further and pops out another q-qbar or
diquark-antidiquark pair. Then you can form a hadron via traditional
fragmentation. This results in a dropping down in pT and you fall into
the low pT region. Thus, the scaling of v2/n at intermediate pT is not
hydrodynamics. It seems too early to make a very strong conclusion on
this point. Clearly we need to understand the models better.

Also, on the hydrodynamic calculations, there are a few inputs. Initial
conditions, when to start the hydro, when to end the hydro and equation
of state. It would be good to quantify from the literature what the
sensitivity is to all of these inputs. One last point is that even
though our data is at midrapidity, data at more forward rapidities show
large disagreement with hydro. How do we treat this part? Again, using
the Bjorken modeling.

\[4\] High PT Suppression

We have clearly established the suppression of high pt particles, that
these particles come from jets, and that they show a large away side
modification.

On the correlation side, we have a lot of unpublished data that I have
not fully digested. We have to be very careful about using this data to
draw strong conclusions. Pushing on those publications is crucial.

I have two items that I think are important.

One is whether the energy loss is partonic and the second is what we
learn if the energy loss is partonic. My feeling is that a large
component of the effect is induced gluon radiation in medium, but that
other parts of the picture are missing. Remember that all the
calculations predicted almost no broadening of the away side jet.
Perhaps the radiated gluons keep re-interacting in medium (which Vitev
et al do not include yet). X.N. Wang\'s paper on why the loss is
partonic (not hadronic) has some good points, but some are weak. One
point is just lorentz factors. This tells me that free vacuum hadrons
cannot be re-scattering, but does not exclude some object building up a
hadronic correlation. Lots of models out there with cross sections that
grow linearly with time at the q-qbar separate to the pion wavefunction
size. Another point is the lack of suppression at CERN. This is a tricky
issue - see the recent paper by David d-Enterria. I must say that I
generally do not like papers that go back and re-fit, plot, select, etc.
older data to find new conclusions. You may fix some old errors, but you
also don\'t know the details of the analysis and other possible issues.
I am always somewhat suspect of the statement of no loss at CERN. Pt is
always pretty low (maybe into the hydro range - see Peitzmann hydro fits
of pizero). Terry Awes mentioned to me that even though X.N. Wang
matches the central data, the trend with centrality of the WA98 data
does not follow pQCD with just increasing Cronin. Any comment Terry? I
have some more comments on how to deal with lower energies in the last
section of this text. Another comment is similar to Mike\'s about the
correlations. This is a strong point, and we need published results to
back it up.

Another point that is good is that with formation time and hadron
re-interactions you would expect the suppression to decrease with pT. We
do not see this. However, I should point out that all models of partonic
energy loss also said that suppression should decrease with pt. Only
after the first data, with a balance of Cronin, shadowing, and energy
loss does Vitev et al. get it to be flat.

One thing that still sticks out as odd is the HERMES data. I like X.N
Wang\'s calculation of energy loss in a cold nucleus that agrees with
the modified fragmentation functions from HERMES. However, HERMES now
published results for different final state hadron species. They see big
differences in the suppression, and the order seems to scale with the
hadron-nucleon cross section. X.N. predicts no hadron dependence since
the parton escapes the nucleus before fragmenting in vacuum into the
leading hadron. Does some type of hadronic wavefunction begin developing
in the nucleus that interacts? I emailed X.N. and he suggested that
maybe struck anti-quarks that lead to antiprotons, etc. might have a
larger annihilation probability in the nucleus and this might explain
things. No paper or calculation yet.

Okay, putting these caveats aside, what do we learn? A long time ago
Miklos explained to me that the radiation is only sensitive to the color
charge density and time profile, not whether the color charges are
deconfined or confined in hadrons. I have seen no strong arguement
against this. Therefore, all we can learn is about the gluon density and
time profile.

Many people mis-quote X.N. Wang\'s paper and say that the energy loss is
an order of magnitude larger than in a cold nucleus. Actually, the
energy loss observed in HERMES (implied in Wang\'s calculation) in a
cold nucleus is about the same as the energy loss at RHIC! However, we
know (and do we all agree) that the density is dropping at 1/t at RHIC.
So if you correct for this 1/t, it implies that there would be an order
of magnitude larger energy loss at RHIC if it were static. Thus, the
conclusion about very large energy loss critically depends on our belief
in the time evolution (1/t or 1/t\^4/3 or otherwise).

So we can learn that the gluon density is very high. Miklos and others
argue that since this gluon density agrees with Bjorken density and with
requiring initial density for hydro and color glass and \... this starts
to put together a consistent picture. I agree with this point, but the
question is how quantitative. Note that gluon radiation is infrared
divergent. Al Mueller points out this large sensitivity to the cutoff.
GLV resolves this by having the cutoff as the plasmon frequency -
resulting in calculations with no systematic error and no sensitivity to
the cutoff scale (really?).

Again, I think the main point we have learned in that assuming our
initial overlapping nucleons release a large number of gluons, we can
calculate the suppression of jets - my guess is at the level of factor
of 2 at pt \< 6 GeV and 1.5 for pt \> 6 GeV.

\[5\] Anomalous Baryon Enhancement 2-4 GeV/c

See the above discussion under v2.

\[6\] Charm Results (Single Electrons)

I quote Mike\'s conclusions below, since I disagree with them :)

From Mike = \"6) Charm non-suppression, another major discovery. This
proves that the gluon structure function isn\'t shadowed. \...Is this
the predicted QCD

dead cone effect, or should charm flow. Is the charm pointlike scaling

like the proton pointlike scaling for 2 \< pT \<4.5 GeV/c, i.e. will it

vanish at higher pT.\"

Our published results from 130 GeV, the charm cross section scales with
binary collisions within 50% systematic errors. Although since we have
no 130 GeV p-p results, the scaling is from PYTHIA, or just minimum bias
to central Au-Au events. Thus, from the 130 GeV data I do not think we
have much constraint on shadowing. From the 200 GeV data with p-p and
Au-Au, the constraint is better, but needs to be quantified. I am not
sure we have ruled out 20% gluon shadowing yet. Forward muon results
will be very nice.

The issue of high pT charm and the \"dead-cone\" effect versus
hydrodynamics etc is not yet resolved. Even with the 200 GeV Au-Au
results shown by Sean Kelly at QM, the statistics are quite limited.
Maybe at 2.5 GeV one can say that there is not a factor of 5
suppression, but this is not quantitative enough. Again,

a lot more data from run-4 already on tape.

\[7\] J/Psi Results

I think we are all working hard on the run-4 results. My guess is that
the suppression pattern (no wiggles) will look like the NA50 result.
Remember above some point, the psi\' disappears, and then the j/psi
starts going away. The jpsi is down in NA50 almost to a surface emission
point. My guess is even with our hotter system, we will go to the
surface limit as well. What we will really need are the upsilon states
to say even more.

\[8\] Missing Results

Direct Photons at low pT. Low mass dileptons. I am not sure we can
measure direct photons at low pt with enough accuracy to ever make
strong conclusions. Maybe we should be looking at Jack Sandweiss\' idea
of 2 photon HBT. The low mass dileptons are crucial. They measure the
parton correlations in the medium. The phi -\> ee is not enough because
the lifetime is just too long. In all the above discussion there is lots
of speculation on new quasi-particle configuration, but no measurements.
So we need the low mass region.

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

\(3\) OTHER REMARKS AND STAYING TRUE TO SCIENCE

\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\--

There may be a large desire to define the QGP so that we have discovered
it at RHIC, but it was not there at SPS or AGS. We should stay true to
the science and avoid this desire.

My feeling is that it is hard to say at lower energies. What is J/psi
suppression at the AGS (Tom and others never got to try this
measurement)? What does a struck parton do when propagating through AGS
matter? We have no idea. I think it is fair to say that many probes are
only available at RHIC and that makes it a unique place to measure the
properties of the medium.

The same might even be said of comparing to proton-proton. We may form
QGP in a small volume in p-pbar (remember Bjorken\'s baked alaska
picture). However, it is too small to probe with many of our tools.
Also, we want to see collectivity. We should keep an open mind, and make
positive statements about what we see at RHIC, and not make too many
negative statements about what is not seen in other systems.

One key items is whether various models have a consistent and correct
space-time picture. That is where real strength can be drawn in putting
together hydro, energy loss, etc. But we need to evaluate whether this
is a reasonable space-time picture and whether the models are really
using it consistently.