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Anomalous J / psi suppression in Pb + Pb collisions at 158-A-GeV/c

The NA50 collaboration Gonin, Michel ; Abreu, M.C. ; Alexa, C. ; et al.
Nucl.Phys.A 610 (1996) 404C-417C, 1996.
Inspire Record 432728 DOI 10.17182/hepdata.36494

Cross sections for J ψ,ψ′ and Drell-Yan production in Pb+Pb collisions at 158×A GeV/c are presented and compared with results obtained by the NA38 and NA51 collaborations. The Pb+Pb data have been collected by the NA50 collaboration using the NA38 dimuon spectrometer. The Drell-Yan mechanism is found to scale as (A projectile · B target ) in p+B target and A projectile + B target collisions including Pb+Pb collisions. Regarding J ψ , an anomalous suppression is observed in Pb+Pb collisions with respect to the suppression observed in p+B target , O+B target and S+U collisions. The cross section ratios ψ′ ( J ψ ) are similar in Pb+Pb and S+U collisions.

2 data tables
Table 1

No description provided.

Table 2

No description provided.


J / psi and Drell-Yan cross-sections in Pb Pb interactions at 158 GeV/c per nucleon

The NA50 collaboration Abreu, M.C. ; Alessandro, B. ; Alexa, C. ; et al.
Phys.Lett.B 410 (1997) 327-336, 1997.
Inspire Record 459315 DOI 10.17182/hepdata.5631

First results are reported on J ψ and Drell-Yan cross-sections in PbPb reactions at 158 GeV/ c per nucleon. The ratio of cross-sections σ J/ψ /σ DY is studied as a function of the impact parameter of the collision estimated from the measured transverse energy.

5 data tables
Table 1

No description provided.

Table 2

No description provided.

Table 3

The Drell-Yan cross sections are taken in the mass interval 2.9 to 4.5 GeV. SIG/SIG ratio are free from most systematic errors.

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Observation of a threshold effect in the anomalous J/psi suppression.

The NA50 collaboration Abreu, M.C ; Alessandro, B ; Alexa, C ; et al.
Phys.Lett.B 450 (1999) 456-466, 1999.
Inspire Record 499915 DOI 10.17182/hepdata.49189

We report on a search for a phase transition from ordinary nuclear matter to a state of deconfined quarks and gluons as predicted by lattice QCD calculations. A new measurement of charmonium production in Pb-Pb interactions at 158 GeV/ c per nucleon agrees with our previous results and confirms the anomalous J/ ψ suppression we had already observed on a significantly smaller data sample. New event selection and analysis techniques show that, for peripheral collisions, the J/ ψ cross-section per nucleon-nucleon collision agrees with the precise suppression pattern inferred from a wide range of measurements extending from p-p up to S-U collisions. As the collisions become more central, the Pb-Pb cross-section exhibits a clear departure from this normal behaviour. The onset of the anomalous J/ ψ suppression reported here is the first clear observation of a threshold effect in heavy ion collisions and can be considered as a strong indication of the production of a deconfined quark-gluon phase in central Pb-Pb collisions.

2 data tables
Table 1

The J/PSI cross section is the cross section for decay to muon pairs.

Table 2

The J/PSI cross section is the cross section for decay to muon pairs. The ratios in this taBLE Are obtained from the minimum bias sample of events. See text if article for details.