J/psi and psi' production in p, O and S induced reactions at SPS energies.

Abreu, M.C. ; Astruc, J. ; Baglin, C. ; et al.
Phys.Lett.B 466 (1999) 408-414, 1999.
Inspire Record 507044 DOI 10.17182/hepdata.42673

The production of the J/ ψ and ψ ′ charmonia states has been studied, through their dimuon decay, in proton, Oxygen and Sulphur induced reactions, by the NA38 experiment at the CERN SPS. The proton data was collected with beams of 200 and 450 GeV, while the ion beams had an energy of 200 GeV per incident nucleon. The J/ ψ production cross-section per nucleon-nucleon collision exhibits a remarkably continuous pattern, as a function of the product of the mass numbers of the interacting nuclei, from pp up to S-U reactions. The same pattern is observed within S-U collisions, as a function of the collision centrality. While in p-A interactions both charmonia states exhibit the same A-dependence, in S-U collisions the ψ ′ production is very strongly suppressed.

6 data tables

Results of fitting the 200 and 450 GeV J/PSI data separately with a power law parametrization SIG=SIG0*(A*B)**POWER, where A and B are the beam and targetmass numbers. The value obtained from a combined fit is also given, as well as the ratio between the values of SIG0 for the 200 and 450 GeV data sets.

The J/PSI cross sections per nucleon (times the BR to di-muons) rescaled to 200 GeV/nucleon, using the SIG0 ratio detemined in the previous table, and to the cm rapidity window 0 to 1. The errors are combined statistical and systematic.

The ratio between the PSI(3685) and the J/PSI production cross section, times their BR into di-muons, at an incident beam energy of 450 GeV per nucleon. The errors are combined statistical and systematic.

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Anomalous J / psi suppression 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) 337-343, 1997.
Inspire Record 459314 DOI 10.17182/hepdata.28260

The Drell-Yan and J ψ cross-sections measured in PbPb collisions are compared with the values extrapolated from the results obtained in proton and light ion induced reactions. While the Drell-Yan production exhibits the normal expected behaviour, the yield of J ψ in PbPb interactions is abnormally low, as it lies 9 standard deviations below the expected value. Moreover, the departure from the expected behaviour increases significantly from peripheral to central collisions.

2 data tables

The results from other experiments are also presented.

Different data are rescaled at 200 GeV.