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.

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Charmonium production and nuclear absorption in p A interactions at 450-GeV.

The NA50 collaboration Alessandro, B. ; Alexa, C. ; Arnaldi, R. ; et al.
Eur.Phys.J.C 33 (2004) 31-40, 2004.
Inspire Record 629957 DOI 10.17182/hepdata.30011

The production of ${\rm J}/\psi$ and

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The PSI(3685) to J/PSI cross section ratios.


Bottomonium and Drell-Yan production in p-A collisions at 450 GeV

The NA50 collaboration Alessandro, B. ; Alexa, C. ; Arnaldi, R. ; et al.
Phys.Lett.B 635 (2006) 260-269, 2006.
Inspire Record 712992 DOI 10.17182/hepdata.57411

The NA50 Collaboration has measured heavy-quarkonium production in p-A collisions at 450 GeV incident energy (sqrt(s) = 29.1 GeV). We report here results on the production of the Upsilon states and of high-mass Drell-Yan muon pairs (m > 6 GeV). The cross-section at midrapidity and the A-dependence of the measured yields are determined and compared with the results of other fixed-target experiments and with the available theoretical estimates. Finally, we also address some issues concerning the transverse momentum distributions of the measured dimuons.

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Mean pT and Mean PT**2 for Drell-Yann (4.5<MMUMU<8 GeV/c**2) Errors for Drell-Yann are purely statistical, error value for Upsilon includes a systematical error due to uncertianty in the extrapolation of the drell-yann yield into the upsilon region. The total error is anyway dominated by the statistical contribution.

ALPHA parameter.


Dimuon and charm production in nucleus nucleus collisions at the CERN-SPS.

The NA38 & NA50 collaborations Abreu, M.C. ; Alessandro, B. ; Alexa, C. ; et al.
Eur.Phys.J.C 14 (2000) 443-455, 2000.
Inspire Record 524686 DOI 10.17182/hepdata.57421

Muon pair production in p-A, S-U and Pb-Pb collisions has been studied by the NA38 and NA50 collaborations at the CERN SPS. In this paper we present an analysis of the dimuon invariant mass region bet

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CHARM-CHARMBAR cross section Need to divide by 2 to consider only the XF>0 hemisphere.


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.

1 data table match query

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.


Evidence for deconfinement of quarks and gluons from the J/psi suppression pattern measured in Pb Pb collisions at the CERN-SPS.

The NA50 collaboration Abreu, M.C. ; Alessandro, B. ; Alexa, C. ; et al.
Phys.Lett.B 477 (2000) 28-36, 2000.
Inspire Record 524685 DOI 10.17182/hepdata.57430

The analysis of the data collected by the NA50 experiment in 1998, reported in this paper, extends and clarifies the pattern of the previously observed J/ ψ anomalous suppression. This new measurement, besides providing a deeper understanding of the previous observations, reveals a steady significative decrease in the J/ ψ production rate up to the most central Pb-Pb collisions. It clearly rules out the presently available conventional (hadronic) models of J/ ψ suppression, which unanimously predict a saturation of the J/ ψ rate for central Pb-Pb collisions. On the contrary and together with the sharp onset of the anomalous suppression previously reported, the new observation leads to a global production rate pattern which finds its natural explanation in the framework of the formation of a deconfined state of quarks and gluons.

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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.

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A new measurement of J/psi suppression in Pb-Pb collisions at 158 GeV per nucleon

The NA50 collaboration Alessandro, B. ; Alexa, C. ; Arnaldi, R. ; et al.
Eur.Phys.J.C 39 (2005) 335-345, 2005.
Inspire Record 667013 DOI 10.17182/hepdata.57372

We present a new measurement of J/psi production in Pb-Pb collisions at 158 GeV/nucleon, from the data sample collected in year 2000 by the NA50 Collaboration, under improved experimental conditions with respect to previous years. With the target system placed in vacuum, the setup was better adapted to study, in particular, the most peripheral nuclear collisions with unprecedented accuracy. The analysis of this data sample shows that the (J/psi)/Drell-Yan cross-sections ratio measured in the most peripheral Pb-Pb interactions is in good agreement with the nuclear absorption pattern extrapolated from the studies of proton-nucleus collisions. Furthermore, this new measurement confirms our previous observation that the (J/psi)/Drell-Yan cross-sections ratio departs from the normal nuclear absorption pattern for semi-central Pb-Pb collisions and that this ratio persistently decreases up to the most central collisions.

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Charmonium production in Pb Pb interactions at 158-GeV/c per nucleon.

The NA50 collaboration Ramello, Luciano ; Abreu, M.C. ; Alessandro, B. ; et al.
Nucl.Phys.A 638 (1998) 261-278, 1998.
Inspire Record 481874 DOI 10.17182/hepdata.36232

The NA50 collaboration has measured J/ψ , ψ′ and Drell Yan pair production in Pb Pb interactions at 158 GeV/ c per nucleon at the CERN SPS. Final results from the 1995 run and preliminary ones from the higher statistics 1996 run are presented. A anomalous J/ψ suppression (relative to the Drell-Yan process) has been observed with respect to the suppression pattern established in experiments NA38 and NA51 with proton, oxygen and sulfur beams. The 1996 data allow a detailed study of the suppression pattern in the Pb Pb sample itself, showing a discontinuity around an E T value (the neutral transverse electromagnetic energy) of 50 GeV. The ψ′ is also suppressed relative to Drell-Yan, with a pattern very similar to the one observed in S U collisions. Finally, the p T distributions of dimuons are presented. The average p T 2 of the J/ψ in Pb Pb collisions does not increase any more with E T above 100 GeV.

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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.

4 data tables match query

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.

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).;.

SIG(J/PSI)/SIG(DY) as a function of E(C=ZDC) with the minimum biasanalyses of the 1998 DATA 1998, MB analyses Data extracted from fig with g3data, statistical errors not included and are set to 0, the systematic errors given by g3data due to extraction.

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