2018 Impact factor 4.843
Particles and Fields
Eur. Phys. J. C 14, 443-455
DOI 10.1007/s100520000373

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

The NA38 and NA50 Collaborations

M.C. Abreu7 - B. Alessandro12 - C. Alexa4 - R. Arnaldi12 - J. Astruc9 - M. Atayan14 - C. Baglin2 - A. Baldit3 - M. Bedjidian13 - F. Bellaiche13 - S. Beolè12 - V. Boldea4 - P. Bordalo7 - A. Borhani10 - A. Bussière2 - L. Capelli13 - V. Capony2 - L. Casagrande7 - J. Castor3 - T. Chambon3 - B. Chaurand10 - I. Chevrot3 - B. Cheynis13 - E. Chiavassa12 - C. Cicalò5 - T. Claudino7 - M.P. Comets9 - N. Constans10 - S. Constantinescu4 - J. Cruz7 - A. De Falco5 - N. De Marco12 - G. Dellacasa1 - A. Devaux3 - S. Dita4 - O. Drapier13,6 - L. Ducroux13 - B. Espagnon3 - J. Fargeix3 - F. Fleuret10 - P. Force3 - M. Gallio12 - Y.K. Gavrilov8 - C. Gerschel9 - P. Giubellino12 - M.B. Golubeva8 - M. Gonin10 - A.A. Grigorian14 - J.Y. Grossiord13 - F.F. Guber8 - A. Guichard13 - H. Gulkanyan14 - R. Hakobyan14 - R. Haroutunian13 - M. Idzik12 - D. Jouan9 - T.L. Karavitcheva8 - L. Kluberg10 - A.B. Kurepin8 - Y. Le Bornec9 - C. Lourenço6 - P. Macciotta5 - M. Mac Cormick9 - A. Marzari-Chiesa12 - M. Masera12 - A. Masoni5 - S. Mehrabyan14 - M. Monteno12 - S. Mourgues3 - A. Musso12 - F. Ohlsson-Malek13 - P. Petiau10 - A. Piccotti12 - J.R. Pizzi13 - G. Puddu5 - C. Quintans7 - C. Racca11 - L. Ramello1 - S. Ramos7 - P. Rato-Mendes7 - L. Riccati12 - A. Romana10 - I. Ropotar6 - P. Saturnini3 - E. Scomparin12 - S. Serci5 - R. Shahoyan7 - S. Silva7 - M. Sitta1 - C. Soave12 - P. Sonderegger6 - X. Tarrago9 - N.S. Topilskaya8 - G.L. Usai5 - E. Vercellin12 - L. Villatte9 - N. Willis9

1 Università del Piemonte Orientale, Alessandria and INFN-Torino, Italy
2 LAPP, CNRS-IN2P3, Annecy-le-Vieux, France
3 LPC, Université Blaise Pascal and CNRS-IN2P3, Aubière, France
4 IFA, Bucharest, Romania
5 Università di Cagliari/INFN, Cagliari, Italy
6 CERN, Geneva, Switzerland
7 LIP, Lisbon, Portugal
8 INR, Moscow, Russia
9 IPN, Université de Paris-Sud and CNRS-IN2P3, Orsay, France
10 LPNHE, Ecole Polytechnique and CNRS-IN2P3, Palaiseau, France
11 IRS, Université Louis Pasteur and CNRS-IN2P3, Strasbourg, France
12 Università di Torino/INFN, Torino, Italy
13 IPN, Université Claude Bernard and CNRS-IN2P3, Villeurbanne, France
14 YerPhI, Yerevan, Armenia

Received: 20 December 1999 / Revised version: 4 February 2000 /
Published online: 14 April 2000 - © Springer-Verlag 2000

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.


Copyright Società Italiana di Fisica, Springer-Verlag 2000