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European Physical Journal C 44 (2005) 375-382
The production of $\rho$, $\omega$ and$ \phi$ vector-mesons by protons and sulphur ions with incident momentum of 200 GeV/c per nucleon
M.C. Abreu, J. Astruc1, C. Baglin2, A. Baldit3, M. Bedjidian4, P. Bordalo, G. Borges, A. Bussière2, J. Castor3, B. Chaurand5, I. Chevrot3, B. Cheynis4, A. Devaux3, O. Drapier4, B. Espagnon3, J. Fargeix3, R. Ferreira, P. Force3, C. Gerschel1, J.-Y. Grossiord4, A. Guichard4, J. Guimaraes, R. Haroutunian4, D. Jouan1, L. Kluberg5, C. Lourenço, S. Mourgues3, P. Petiau5, J.-R. Pizzi4, C. Quintans, S. Ramos, A. Romana5, H. Santos, P. Saturnini3, R. Shahoyan, P. Sonderegger, X. Tarrago1
NA38 Collaboration(s)

The production of $\rho$ , $\omega$ and $\phi$ vector-mesons, detected through their $\mu\mu$ decay channel, is studied in p-W, S-S, S-Cu and S-U reactions at 200 GeV/c per nucleon incident momentum. Their inclusive cross-sections are determined in various transverse momentum intervals and their dependence on the projectile and target mass numbers is investigated. The relative yield $B_{\mu\mu}\sigma_{\phi}/(B_{\mu\mu}\sigma_{\rho} + B_{\mu\mu}\sigma_{\omega})$ is measured, both as a function of the transverse momentum, pT, and of the collision centrality. While this ratio exhibits no significant dependence with pT, it clearly increases with the centrality of the collision. Effective temperatures deduced from the transverse mass spectra, $d\sigma/dM_T$ , lead to values of $T_{\rho + \omega}$ equal or slightly higher than $T_{\phi}$ . Both these effective temperatures smoothly increase from p-W to S-U reactions.
1 :  IPNO - Institut de Physique Nucléaire d'Orsay
2 :  LAPP - Laboratoire d'Annecy le Vieux de Physique des Particules
3 :  LPC - Laboratoire de Physique Corpusculaire [Clermont-Ferrand]
4 :  IPNL - Institut de Physique Nucléaire de Lyon
5 :  LLR - Laboratoire Leprince-Ringuet
Physique/Physique des Hautes Energies - Expérience