CERN Accelerating science

• Federico Antinori - Tue, 10 Nov 1998
  

Dear Colleagues,

I would like to share with you a few comments on the new version of the
status report on the Heavy Ion Programme at the CERN SPS.

First of all, I would like to congratulate Berndt and Peter for the high

quality of the document. Having followed the e-mail debate after the
release of the first version, I essentially agree with most the authors'

response to it in producing the second version, although, since I think
that the topic order is not irrelevant at all, I feel that the full
pattern of strangeness enhancement, and in particular the results on the

production of multi-strange hyperons, should be the second topic on the
list due to the quality and unambiguity of the data, and to the sheer
magnitude of the effect.

There is one major point I disagree with: the wording of the final
sentence of the J/psi paragraph.
I think that the confirmation by NA50 of a threshold behaviour in J/psi
production would, per se, indicate a sudden change in the physical
behaviour of highly compressed hadronic matter. The confirmation of such

a sudden effect would in itself be a scientific breakthrough before any
interpretation is attached to it, and a huge boost for the whole field.
Since the deconfinement phase transition predicted by QCD is expected to

produce an effect of this kind, the natural scientific hypothesis would
then be
that this is what is being observed, but we would have to study
carefully the correlation of this effect with changes in the behaviour
of other observables before being able to convince ourselves and the
outside world that QGP has been discovered.
Even such a confirmation would therefore, taken on its own, still "stop
short of furnishing unambiguous evidence", at least to me, that it is
really the deconfinement phase transition that we are witnessing.
I propose to amend the sentence to a new form of the kind:
"Such an effect would indicate a sudden change in the behaviour of
highly compressed hadronic matter, as expected for a deconfinement phase

transition, within the Et-range covered by NA50."

          Best regards,

      Federico Antinori