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 φ and the J/ψ. In p-A collisions we find that, after the subtraction of the combinatorial background due to π 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 × 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.
| Lingua originale | Inglese |
|---|---|
| pagine (da-a) | 443-455 |
| Numero di pagine | 13 |
| Rivista | European Physical Journal C |
| Volume | 14 |
| Numero di pubblicazione | 3 |
| DOI | |
| Stato di pubblicazione | Pubblicato - 2000 |