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The dependence of the anomalous J/psi suppression on the number of participant nucleons.

The NA50 collaboration Abreu, M.C ; Alessandro, B ; Alexa, C ; et al.

Phys.Lett.B 521 (2001) 195-203, 2001.

Inspire Record 564953 DOI 10.17182/hepdata.57435

The observation of an anomalous J/ ψ suppression in Pb–Pb collisions by the NA50 Collaboration can be considered as the most striking indication for the deconfinement of quarks and gluons at SPS energies. In this Letter, we determine the J/ ψ suppression pattern as a function of the forward hadronic energy E ZDC measured in a Zero Degree Calorimeter (ZDC). The direct connection between E ZDC and the geometry of the collision allows us to calculate, within a Glauber approach, the precise relation between the number of participant nucleons N part and E ZDC . Then, we check if the experimental data can be better explained by a sudden or a smooth onset of the anomalous J/ ψ suppression as a function of the number of participants.

6 data tables

Table 1

Minimum Bias E(C=ZDC) spectrum. Data extracted from fig with g3data, statistical errors not included and are set to 0, the systematic errors given by g3data due to extraction.

Table 2

Number of participants as a function of E(C=ZDC) Data exctracted from fig with g3data, the systematic errors given by g3data due to extraction, and those marked (stat) are in this case the r.m.s. of the Npart distribution at fixed E(C=ZDC).;.

Table 3

SIG(J/PSI)/SIG(DY) as a function of E(C=ZDC) with the standard analyses of the 1996 DATA 1996, standard analyses.

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J / psi, psi-prime and muon pair production in p - W and S - U collisions

The NA38 collaboration Abreu, M.C. ; Baglin, C. ; Baldit, A. ; et al.

Nucl.Phys.A 566 (1994) 77C-85C, 1994.

Inspire Record 358346 DOI 10.17182/hepdata.36538

In this paper we present a study on the production of the J ψ and ψ′ resonances, decaying into muon pairs, in S-U collisions, at 200 GeV per incident nucleon. We find that the ratio between ψ′ and tJ ψ yields decreases as E T , the neutral transverse energy produced in the collision, increases. There is also a clear decrease of this ratio when going from p-W to S-U interactions. Assuming the high mass continuum to be Drell-Yan we discuss the possible understanding of the intermediate dimuon mass region as a superposition of Drell-Yan (extrapolated down in mass) and muon pairs from the semileptonic decays of charmed mesons. The p-W data is found to be explained by this procedure. However, the S-U data seems to be incompatible with a linear extrapolation from the proton-nucleus results.

4 data tables

Table 1

THE NEUTRAL TRANSVERSE ENERGY PRODUCED IN THE COLLISION > 15 GEV.

Table 2

THE NEUTRAL TRANSVERSE ENERGY PRODUCED IN THE COLLISION > 15 GEV.

Table 3

THE NEUTRAL TRANSVERSE ENERGY PRODUCED IN THE COLLISION > 15 GEV.

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