Data di Pubblicazione:
1999
Abstract:
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.
Tipologia CRIS:
03A-Articolo su Rivista
Elenco autori:
M.C Abreu;B Alessandro;C Alexa;R Arnaldi;J Astruc;M Atayan;C Baglin;A Baldit;M Bedjidian;F Bellaiche;S Beolè;V Boldea;P Bordalo;A Bussière;V Capony;L Casagrande;J Castor;T Chambon;B Chaurand;I Chevrot;B Cheynis;E Chiavassa;C Cicalò;M.P Comets;N Constans;S Constantinescu;J Cruz;A De Falco;G Dellacasa;N De Marco;A Devaux;S Dita;O Drapier;B Espagnon;J Fargeix;S.N Filippov;F Fleuret;P Force;M Gallio;L Gatignon;Y.K Gavrilov;C Gerschel;P Giubellino;M.B Golubeva;M Gonin;A.A Grigorian;J.Y Grossiord;F.F Guber;A Guichard;H Gulkanyan;R Hakobyan;R Haroutunian;M Idzik;D Jouan;T.L Karavitcheva;L Kluberg;A.B Kurepin;Y Le Bornec;C Lourenço;L Luquin;M Mac Cormick;P Macciotta;A Marzari-Chiesa;M Masera;A Masoni;S Mehrabyan;M Monteno;S Mourgues;A Musso;F Ohlsson-Malek;P Petiau;A Piccotti;J.R Pizzi;W.L Prado da Silva;F Prino;G Puddu;C Quintans;C Racca;L Ramello;S Ramos;P Rato-Mendes;L Riccati;A Romana;I Ropotar;P Saturnini;E Scomparin;S Serci;R Shahoyan;S Silva;M Sitta;C Soave;P Sonderegger;X Tarrago;P Temnikov;N.S Topilskaya;G.L Usai;E Vercellin;N Willis
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