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Start Over Author "Chambon, T." Topic high energy physics::experiment
8 results on '"Chambon, T."'

1. $J/\psi$ suppression in Pb-Pb collisions at CERN SPS

Author

Prino, Francesco, Abreu, M.C., Alessandro, B., Alexa, C., Arnaldi, R., Ataian, M., Baglin, C., Baldit, A., Bedjidian, M., Beole, S., Boldea, V., Bordalo, P., Bussiere, A., Capelli, L., Casagrande, L., Castor, J., Chambon, T., Chaurand, B., Chevrot, I., Cheynis, B., Chiavassa, E., Cicalo, C., Claudino, T., Comets, M.P., Constans, N., Constantinescu, S., De Marco, N., De Falco, A., Dellacasa, G., Devaux, A., Dita, S., Drapier, O., Ducroux, L., Espagnon, B., Fargeix, J., Force, P., Gallio, M., Gavrilov, Y.K., Gerschel, C., Giubellino, P., Golubeva, M.B., Gonin, M., Grigorian, A.A., Grossiord, J.Y., Guber, F.F., Guichard, A., Gulkanian, H., Hakobian, R., Haroutunian, R., Idzik, M., Jouan, D., Karavitcheva, T.L., Kluberg, L., Kurepin, A.B., Le Bornec, Y., Lourenco, C., Macciotta, P., MacCormick, M., Marzari-Chiesa, A., Masera, M., Masoni, A., Mehrabian, S., Monteno, M., Musso, A., Petiau, P., Piccotti, A., Pizzi, J.R., Puddu, G., Quintans, C., Ramos, S., Ramello, L., Rato Mendes, P., Riccati, L., Romana, A., Ropotar, I., Saturnini, P., Scomparin, E., Serci, S., Shahoian, R., Silva, S., Sitta, M., Soave, C., Sonderegger, P., Tarrago, X., Topilskaya, N.S., Usai, G.L., Vercellin, E., Villatte, L., and Willis, N.

Subjects
High Energy Physics::Lattice, High Energy Physics::Phenomenology, Nuclear Theory, High Energy Physics::Experiment, Nuclear Experiment, Particle Physics - Experiment
Abstract

The NA38 and NA50 experiments at the CERN SPS have measured charmonium production in different colliding systems with the aim of observing a phase transition from ordinary hadronic matter towards a state in which quarks and gluons are deconfined (Quark Gluon Plasma, QGP). In fact it was predicted that the J/psi yield should be suppressed in deconfined matter. The analysis of the data collected by the NA50 experiment with Pb-Pb collisions at 158 GeV/c per nucleon shows that the J/psi is anomalously suppressed in central collisions and the observed pattern can be considered as a strong indication for QGP production. The NA38 and NA50 experiments at the CERN SPS have measured charmonium production in different colliding systems with the aim of observing a phase transition from ordinary hadronic matter towards a state in which quarks and gluons are deconfined (Quark Gluon Plasma, QGP). In fact it was predicted that the J/psi yield should be suppressed in deconfined matter. The analysis of the data collected by the NA50 experiment with Pb-Pb collisions at 158 GeV/c per nucleon shows that the J/psi is anomalously suppressed in central collisions and the observed pattern can be considered as a strong indication for QGP production.

Published
2001

2. Low mass dimuon production in proton and ion induced interactions at SPS

Author

Abreu, M C., Alessandro, B., Alexa, C., Arnaldi, R., Astruc, J., Atayan, M., Baglin, C., Baldisseri, A., Baldit, A., Bedjidian, M., Bellaiche, F., Beole, S., Boldea, V., Bordalo, P., Bussiere, A., Capony, V., Casagrande, L., Castor, J., Chambon, T., Chaurand, B., Chevrot, I., Cheynis, B., Chiavassa, E., Cicalo, C., Comets, M P., Constans, N., Constantinescu, S., Contardo, D., De Falco, A., Dellacasa, G., De Marco, N., Descroix, E., Devaux, A., Dita, S., Drapier, O., Espagnon, B., Fargeix, J., Ferreira, R., Filippov, S N., Fleuret, F., Force, P., Gallio, M., Gavrilov, Y K., Gerschel, C., Giubellino, P., Golubeva, M B., Gonin, M., Gorodetzky, P., Grigorian, A A., Grossiord, J.-Y., Guber, F F., Guichard, A., Guillaud, J.P., Gulkanyan, H., Hakobyan, R., Haroutunian, R., Idzik, M., Jouan, D., Karavitcheva, T L., Kluberg, L., Kossakowski, R., Kurepin, A B., Le Bornec, Y., Liaud, P., Lourenco, C., Mac Cormick, M., Macciotta, P., Marzari-Chiesa, A., Masera, M., Masoni, A., Mehrabyan, S., Monteno, M., Mourgues, S., Musso, A., Ohlsson-Malek, F., Petiau, P., Piccotti, A., Pizzi, J.-R., Prino, F., Puddu, G., Quintans, C., Racca, C., Ramello, L., Ramos, S., Rato-Mendes, P., Riccati, L., Romana, A., Ronceux, B., Ropotar, I., Saturnini, P., Scomparin, E., Serci, S., Shahoyan, R., Silva, S., Sitta, M., Soave, C., Sonderegger, P., Staley, F., Tarrago, X., Topilskaya, N S., Usai, G L., Varela, J., Vercellin, E., Willis, N., Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Laboratoire d'Annecy de Physique des Particules (LAPP), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire de Lyon (IPNL), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Laboratoire Leprince-Ringuet (LLR), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), ALICE, Institut de Physique des 2 Infinis de Lyon (IP2I Lyon), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), NA38, Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Annecy de Physique des Particules (LAPP/Laboratoire d'Annecy-le-Vieux de Physique des Particules), Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), and Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL)

Subjects
Physics, Particle physics, Muon, Physics and Astronomy (miscellaneous), Proton, 010308 nuclear & particles physics, 01 natural sciences, Spectral line, Ion, Nuclear physics, Distribution (mathematics), [PHYS.HPHE]Physics [physics]/High Energy Physics - Phenomenology [hep-ph], 0103 physical sciences, Production (computer science), High Energy Physics::Experiment, 010306 general physics, Low Mass, Nuclear Experiment, Engineering (miscellaneous), Particle Physics - Experiment, Bar (unit)
Abstract

The low mass dimuon spectra collected in p-U collisions by the NA38 experiment significantly exceeds the total cross section expected from previous analysis, done by other experiments. The ‘excess’ events have a harder $p_{\mathrm{T}}$ distribution than the muon pairs from $\eta$ and $\omega$ Dalitz decays, expected to dominate the mass window 0.4–0.65 GeV/ $c^2$ . We conjecture that the excess events may be due to $q\bar{q}$ annihilations, negligible at low $p_{\mathrm{T}}$ but made visible by the $m_{\mathrm{T}}$ cut applied in the NA38 data. Taking this assumption to parametrise the p-U spectra, we proceed with the corresponding analysis of the S-Cu, S-U and Pb-Pb data, collected by the NA38 and NA50 experiments, comparing the measured low mass dimuon spectra with the ‘expected cocktail’.

Published
2000

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

Author

Abreu, M. C., Alessandro, B., Alexa, C., Arnaldi, R., Astruc, J., Atayan, M., Baglin, C., Baldit, A., Bedjidian, M., Bellaiche, F., Beole', Stefania, Boldea, V., Bordalo, P., Borhani, A., Bussiere, A., Capelli, L., Capony, V., Casagrande, L., Castor, J., Chambon, T., Chaurand, B., Chevrot, I., Cheynis, B., Chiavassa, Emilio Luciano, Cicalo, C., Claudino, T., Comets, M. P., Constans, N., Constantinescu, S., Cruz, J., De Falco, A., De Marco, N., Dellacasa, G., Devaux, A., Dita, S., Drapier, O., Ducroux, L., Espagnon, B., Fargeix, J., Fleuret, F., Force, P., Gallio, Mauro, Gavrilov, Y. K., Gerschel, C., Giubellino, P., Golubeva, M. B., Gonin, M., Grigorian, A. A., Grossiord, J. Y., Guber, F. F., Guichard, A., Gulkanyan, H., Hakobyan, R., Haroutunian, R., Idzik, M., Jouan, D., Karavitcheva, T. L., Kluberg, L., Kurepin, A. B., Le Bornec, Y., Lourenco, C., Macciotta, P., Mac Cormick, M., Marzari Chiesa, A., Masera, Massimo, Masoni, A., Mehrabyan, S., Monteno, M., Mourgues, S., Musso, A., Fairouz, Malek, Petiau, P., Piccotti, A., Pizzi, J. R., Puddu, G., Quintans, C., Racca, C., Ramello, L., Ramos, S., Rato Mendes, P., Riccati, L., Romana, A., Ropotar, I., Saturnini, P., Scomparin, E., Serci, S., Shahoyan, R., Silva, S., Sitta, M., Soave, C., Sonderegger, P., Tarrago, X., Topilskaya, N. S., Usai, G. L., Vercellin, Ermanno, Villatte, L., Willis, N., Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Annecy de Physique des Particules (LAPP/Laboratoire d'Annecy-le-Vieux de Physique des Particules), Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire de Lyon (IPNL), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Leprince-Ringuet (LLR), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), ALICE, Institut de Physique des 2 Infinis de Lyon (IP2I Lyon), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), NA50, Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Laboratoire d'Annecy de Physique des Particules (LAPP), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Particle physics, Muon, Physics and Astronomy (miscellaneous), Meson, 010308 nuclear & particles physics, Nuclear Theory, Drell–Yan process, 01 natural sciences, Nuclear physics, Pair production, Antimatter, [PHYS.HPHE]Physics [physics]/High Energy Physics - Phenomenology [hep-ph], 0103 physical sciences, Invariant mass, High Energy Physics::Experiment, Charm (quantum number), 010306 general physics, Nucleon, Nuclear Experiment, Engineering (miscellaneous), Particle Physics - Experiment
Abstract

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 between the $\phi$ and the J/ $\psi$ . In p-A collisions we find that, after the subtraction of the combinatorial background due to $\pi$ and K decays, the superposition of dimuons from semi-leptonic decays of D mesons and from the Drell-Yan process reproduces well the measured mass and transverse momentum spectra. The yield of open charm dimuons required to fit our data leads to a charm production cross section in good agreement with previous measurements. A linear extrapolation of the p-A sources with the product of the mass numbers of the projectile and target nuclei, $A\times B$ , underestimates the dimuon yield measured in S-U and Pb-Pb collisions. The excess increases with the number of participant nucleons, and the ratio between the observed dimuon yield and the expected sources reaches a factor 2 for central Pb-Pb interactions. The kinematical distributions of the measured dimuon excess are compatible with those expected from the open charm contribution.

Published
2000

4. Intermediate mass dimuons in NA38/NA50

Author

Abreu, M. C., Alessandro, B., Alexa, C., Arnaldi, R., Astruc, J., Ataian, M., Baglin, C., Baldit, A., Bedjidian, M., Bellaiche, F., Beole, S., Boldea, V., Bordalo, P., Bussiere, A., Capony, V., Casagrande, L., Castor, J., Chambon, T., Chaurand, B., Chevrot, I., Cheynis, B., Chiavassa, E., Cicalo, C., Comets, M. P., Constantinescu, S., Cruz, J., Falco, A., Marco, N., Dellacasa, G., Devaux, A., Dita, S., Drapier, O., Espagnon, B., Fargeix, J., Filippov, S. N., Fleuret, F., Force, P., Gallio, M., Gavrilov, Yu K., Gerschel, C., Giubellino, P., Golubeva, M. B., Gonin, M., Grigorian, A. A., Grossiord, J. Y., Guber, F. F., Guichard, A., Gulkanian, H., Hakobian, R., Haroutunian, R., Idzik, M., Jouan, D., Karavicheva, T. L., Kluberg, L., Kurepin, A. B., Le Bornec, Y., Lourenco, C., Maccormick, M., Macciotta, P., Marzari-Chiesa, A., Masera, M., Masoni, A., Megrabian, S. S., Mourgues, S., Musso, A., Malek, Fairouz, Petiau, P., Piccotti, A., Pizzi, J. R., Prado Da Silva, W. L., Puddu, G., Quintans, C., Racca, C., Ramello, L., Ramos, S., Rato-Mendes, P., Riccati, L., Romana, A., Sartori, S., Saturnini, P., Scomparin, E., Serci, S., Shahoian, R., Silva, S., Soave, C., Sonderegger, P., Tarrago, X., Temnikov, P., Topilskaya, N. S., Gianluca Usai, Vale, C., Vercellin, E., and Willis, N.

Subjects
High Energy Physics::Phenomenology, Nuclear Theory, High Energy Physics::Experiment, Nuclear Experiment, Particle Physics - Experiment
Abstract

The NA38/NA50 experiments have measured, at the CERN SPS, the dimuon production in proton-nucleus and nucleus-nucleus collisions. In this paper it is shown that the mass continuum between the $\phi$ and the $J/{\psi}$ can be satisfactorily described, after having removed the combinatorial background due to uncorrelated $\pi$ and $K$ decays, as a sum of two contributions, namely the Drell-Yan process and the semi-leptonic decay of pairs of charmed mesons, whose mass shape in the acceptance of the experiment has been evaluated using PYTHIA. However, in order to describe the A - B (namely S - U and Pb - Pb) mass spectra, the dimuon yield from open charm decays, which in $p$ - A collisions is found to be consistent with direct open charm measurements from other CERN and FNAL experiments, has to be enhanced with respect to a linear extrapolation of $p$ - A results. The size of the enhancement smoothly increases from peripheral S - U to central Pb - Pb interactions, reaching a factor $\sim$ 3 in central Pb - Pb collisions. The $P_{T}$ distributions of the events in the mass continuum are also compatible with the hypothesis of open charm enhancement in A - B collisions.

Published
1999

5. Results on Charmonium States in Pb-Pb Interactions

Author

Baglin, C, Bussière, A, Capony, V, Baldit, A, Castor, J I, Chambon, T, Chevrot, I, Devaux, A, Espagnon, B, Fargeix, J, Force, P, Mourgues, S, Saturnini, P, Alexa, C, Boldea, V, Constantinescu, S, Dita, S, Cicalò, C, De Falco, A, Macciotta, P, Masoni, A, Puddu, G, Serci, S, Temnikov, P P, Usai, G L, Lourenço, C, Scomparin, E, Sonderegger, P, Abreu, M C, Bordalo, P, Casagrande, L, Cruz, J, Quintans, C, Ramos, S, Shahoyan, R, Silva, S, Vale, C J, Filippov, S N, Gavrilov, Yu K, Golubeva, M B, Guber, F F, Karavitcheva, T L, Kurepin, A B, Topilskaya, N S, Astruc, J, Comets, M P, Gerschel, C, Jouan, D, Le Bornec, Y, MacCormick, M, Tarrago, X, Willis, N, Chaurand, B, Fleuret, F, Gonin, M, Kluberg, L, Petiau, P, Romana, A, Racca, C, Alessandro, B, Arnaldi, R, Beolè, S, Chiavassa, E, De Marco, N, Dellacasa, G, Gallio, M, Giubellino, P, Idzik, M, Marzari-Chiesa, A, Masera, M, Musso, A, Piccotti, A, Prado da Silva, W L, Ramello, L, Rato-Mendes, P, Riccati, L, Sartori, S M, Soave, C, Vercellin, Ermanno, Bedjidian, Marc, Bellaiche, F G, Cheynis, B, Drapier, O, Grossiord, J Y, Guichard, A, Haroutunian, R, Ohlsson-Malek, F, Pizzi, J R, Ataian, M R, Grigorian, A A, Gulkanian, H R, Hakobyan, R S, and Mehrabyan, S S

Subjects
High Energy Physics::Phenomenology, Nuclear Theory, High Energy Physics::Experiment, Nuclear Experiment, Particle Physics - Experiment
Abstract

We present cross-sections for J/$\psi$, $\psi^{\prime}$ and Drell-Yan production in lead-lead interactions at 158 GeV/nucleon. The Pb-Pb data, when compared with previous results obtained with lighter target or projectiles, show a similar behaviour for Drell-Yan, but exhibit an anomalous J/$\psi$ suppression, which increases with centrality.

Published
1998

6. Intermediate mass dimuons in NA38/NA50

Author

Abreu, M C., Alessandro, B., Alexa, C., Arnaldi, R., Astruc, J., Atayan, M., Baglin, C., Baldit, A., Bedjidian, M., Bellaiche, F., Beole, S., Boldea, V., Bordalo, P., Bussiere, A., Capony, V., Casagrande, L., Castor, J., Chambon, T., Chaurand, B., Chevrot, I., Cheynis, B., Chiavassa, E., Cicale, C., Comets, M P., Constantinescu, S., Cruz, J., Defalco, A., de Marco, N., Dellacasa, G., Devaux, A., Dita, S., Drapier, O., Espagnon, B., Fargeix, J., Filippov, S N., Fleuret, F., Force, P., Gallio, M., Gavrilov, y K., Gerschel, C., Giubellino, P., Golubeva, M B., Gonin, M., Grigorian, a A., Grossiord, J.-Y., Guber, F F., Guichard, A., Gulkanyan, H., Hakobyan, R., Haroutunian, R., Jouan, D., Karavitcheva, T L., Kluberg, L., Kurepin, a B., Le Bornec, Y., Lourenco, C., Mac Cormick, M., Macciotta, P., Marzari-Chiesa, A., Masera, M., Masoni, A., Mehrabyan, S., Mourgues, S., Musso, A., Ohlsson-Malek, F., Petiau, P., Piccotti, A., Pizzi, J.-R., Prado da Silva, W L., Puddu, G., Quintans, C., Racca, C., Ramello, L., Ramos, S., Rato-Mendes, P., Riccati, L., Romana, A., Sartori, S., Saturnini, P., Scomparin, E., Serci, S., Shahoyan, R., Silva, S., Soave, C., Sonderegger, P., Tarrago, X., Temnikov, P., Topilskaya, N S., Usai, G L., Vercellin, E., Willis, N., Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Laboratoire d'Annecy de Physique des Particules (LAPP), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire de Lyon (IPNL), Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Laboratoire Leprince-Ringuet (LLR), Centre National de la Recherche Scientifique (CNRS)-École polytechnique (X)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), ALICE, Institut de Physique des 2 Infinis de Lyon (IP2I Lyon), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), NA38, Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Annecy de Physique des Particules (LAPP/Laboratoire d'Annecy-le-Vieux de Physique des Particules), Centre National de la Recherche Scientifique (CNRS)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), and Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL)

Subjects
[PHYS.HPHE]Physics [physics]/High Energy Physics - Phenomenology [hep-ph], High Energy Physics::Phenomenology, Nuclear Theory, High Energy Physics::Experiment, Nuclear Experiment
Abstract

The NA38/NA50 experiments have measured, at the CERN SPS, the dimuon production in proton--nucleus and nucleus--nucleus collisions. In this paper it is shown that the mass continuum between the $\phi$ and the $J/{\psi}$ can be satisfactorily described, after having removed the combinatorial background due to uncorrelated $\pi$ and $K$ decays, as a sum of two contributions, namely the Drell--Yan process and the semi--leptonic decay of pairs of charmed mesons, whose mass shape in the acceptance of the experiment has been evaluated using PYTHIA. However, in order to describe the A--B (namely S--U and Pb--Pb) mass spectra, the dimuon yield from open charm decays, which in p--A collisions is found to be consistent with direct open charm measurements from other CERN and FNAL experiments, has to be enhanced with respect to a linear extrapolation of p--A results. The size of the enhancement smoothly increases from peripheral S--U to central Pb--Pb interactions, reaching a factor $\sim$ 3 in central Pb--Pb collisions. The $p_T$ distributions of the events in the mass continuum are also compatible with the hypothesis of open charm enhancement in A--B collisions.

Published
1998

7. The search for the quark-gluon plasma study of production of charmed bound states in Pb-Pb collisions at 158 GeV/nucleon

Author

Abreu, M.C., Alessandro, B., Alexa, C., Arnaldi, R., Astruc, J., Atayan, M., Baglin, C., Baldit, A., Bedjidian, M., Bellaiche, F., Beole, S., Boldea, V., Bordalo, P., Bussiere, A., Capony, V., Casagrande, L., Castor, J., Chambon, T., Chaurand, B., Chevrot, I., Cheynis, B., Chiavassa, E., Cicalo, C., Comets, M.P., Constantinescu, S., Cruz, J., de Falco, A., de Marco, N., Dellacasa, G., Devaux, A., Dita, S., Drapier, O., Espagnon, B., Fargeix, J., Filippov, S.N., Fleuret, F., Force, P., Gallio, M., Gavrilov, Y.K., Gerschel, C., Giubellino, P., Golubeva, M.B., Gonin, M., Grigorian, A., Grossiord, J.-Y., Guber, F.F., Guichard, A., Gulkanyan, H., Hakobyan, R., Haroutunian, R., Idzik, M., Jouan, D., Karavitcheva, T.L., Kluberg, L., Kurepin, A.B., Le Bornec, Y., Lourenco, C., Mac Cormick, M., Macciotta, P., Marzari-Chiesa, A., Masera, M., Masoni, A., Mehrabian, S., Mourgues, S., Musso, A., Ohlsson-Malek, F., Petiau, P., Piccotti, A., Pizzi, J.-R., Prado da Silva, W.L., Puddu, G., Quintans, C., Racca, C., Ramello, L., Ramos, S., Rato-Mendes, P., Riccati, L., Romana, A., Sartori, S., Saturnini, P., Scomparin, E., Serci, S., Shahoyan, R., Silva, S., Soave, C., Sondereger, P., Tarrago, X., Temnikov, P., Topilskaya, N.S., Usai, G.L., Vale, C., Vercellin, E., Willis, N., Laboratoire d'Annecy de Physique des Particules (LAPP), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Savoie Mont Blanc (USMB [Université de Savoie] [Université de Chambéry])-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire de Lyon (IPNL), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), ALICE, Institut de Physique des 2 Infinis de Lyon (IP2I Lyon), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Tran Thanh Van J., NA50, Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), and Chadelas, Michèle

Subjects
[PHYS.HPHE] Physics [physics]/High Energy Physics - Phenomenology [hep-ph], [PHYS.HPHE]Physics [physics]/High Energy Physics - Phenomenology [hep-ph], Nuclear Theory, High Energy Physics::Experiment, Nuclear Experiment
Abstract

The NA50 Collaboration has studied the production of dimuons originating from J/psi, psi' and Drell-Yan virtual photons in Pb-Pb collisions at 158 GeV/nucleon. The J/psi production differs from what is expected when extrapolating from previously studied colliding systems. Going from peripheral to central collisions, the J/psi suppression presents a sudden and clear drop-off which we refer here as an "anomalous suppression".

Published
1998

8. Anomalous $J/\psi$ suppression in 158 GeV/c Pb-Pb interactions at the CERN SPS

Author

Baglin, C, Abreu, M C, Alessandro, B, Alexa, C, Astruc, J, Baldit, A, Bellaiche, F G, Bedjidian, Marc, Beolè, S, Borhani, A, Boldea, V, Bonazzola, G C, Bordalo, P, Bussière, A, Capony, V, Castor, J I, Cerú, M, Chambon, T, Chaurand, B, Chevrot, I, Cheynis, B, Chiavassa, E, Cicalò, C, Constantinescu, S, Dabrowski, W, De Falco, A, Dellacasa, G, De Marco, N, Devaux, A, Dita, S, Drapier, O, Espagnon, B, Fargeix, J, Fleuret, F, Force, P, Gallio, M, Gavrilov, Yu K, Gerschel, C, Giubellino, P, Golubeva, M B, Gonin, M, Gorodetzky, P, Grossiord, J Y, Guaita, P, Guber, F F, Guichard, A, Haroutunian, R, Idzik, M, Jouan, D, Karavitcheva, T L, Kossakowski, R, Kluberg, L, Kurepin, A B, Le Bornec, Y, Landaud, G, Lourenço, C, Luquin, Lionel, Macciotta, P, Ohlsson-Malek, F, Marzari-Chiesa, A, Masera, M, Masoni, A, Mourgues, S, Musso, A, Petiau, P, Prado da Silva, W L, Piccotti, A, Pizzi, J R, Puddu, G, Racca, C, Ramello, L, Ramos, S, Rato-Mendes, P, Riccati, L, Romana, A, Sartori, S M, Saturnini, P, Scomparin, E, Shao, Ian R, Silva, S, Serci, S, Sonderegger, P, Tarrago, X, Temnikov, P P, Topilskaya, N S, Usai, G L, Vercellin, Ermanno, and Willis, N

Subjects
High Energy Physics::Lattice, High Energy Physics::Phenomenology, Nuclear Theory, High Energy Physics::Experiment, Nuclear Physics - Experiment, Nuclear Experiment
Abstract

Heavy ion production of J/ψ mesons has been studied at CERN for a decade, in search for the Quark-Gluon Plasma predicted by lattice-QCD. The suppression observed very early in O-Cu, O-U and S-U reactions has been shown to be eventually explained by nuclear absorption, and follow the same exponential behavior as the proton-nucleus reactions. The new Pb-Pb data deviate from this behavior very strongly, indicating the onset of a new regime in J/ψ suppression.

Published
1997

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