| Verf.angabe: | R. Arnaldi, K. Banicz, K. Borer, J. Castor, B. Chaurand, W. Chen, C. Cicalò, A. Colla, P. Cortese, S. Damjanovic, A. David, A. De Falco, A. Devaux, L. Ducroux, H. En’yo, J. Fargeix, A. Ferretti, M. Floris, A. Förster, P. Force, N. Guettet, A. Guichard, H. Gulkanian, J.M. Heuser, P. Jarron, M. Keil, L. Kluberg, Z. Li, C. Lourenço, J. Lozano, F. Manso, P. Martins, A. Masoni, A. Neves, H. Ohnishi, C. Oppedisano, P. Parracho, P. Pillot, T. Poghosyan, G. Puddu, E. Radermacher, P. Ramalhete, P. Rosinsky, E. Scomparin, J. Seixas, S. Serci, R. Shahoyan, P. Sonderegger, H.J. Specht, R. Tieulent, A. Uras, G. Usai, R. Veenhof, H. K. Wöhri |
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| Abstract: | The NA60 experiment has studied low-mass muon pair production in proton-nucleus collisions with a system of Be, Cu, In, W, Pb and U targets, using a 400 GeV proton beam at the CERN SPS. The transverse momentum spectra of the ρ/ωρ/ω\rho /\omega and ϕϕ\phi mesons are measured in the full pTpTp_{\mathrm {T}} range accessible, from pT=0pT=0p_{\mathrm {T}}= 0 up to 2GeV/c2GeV/c2 \, {\hbox {GeV/c}}. The nuclear dependence of the production cross sections of the ηη\eta , ωω\omega and ϕϕ\phi mesons has been found to be consistent with the power law σpA∝AασpA∝Aα\sigma _{\mathrm {pA}} \propto {\mathrm {A}}^\alpha , with the αα\alpha parameter increasing as a function of pTpTp_{\mathrm {T}} for all the particles, and an approximate hierarchy αη≈αϕ>αωαη≈αϕ>αω\alpha _\eta \approx \alpha _\phi > \alpha _\omega . The cross section ratios ση/σωση/σω\sigma _\eta /\sigma _\omega , σρ/σωσρ/σω\sigma _\rho /\sigma _\omega and σϕ/σωσϕ/σω\sigma _\phi /\sigma _\omega have been studied as a function of the size A of the production target, and an increase of the ηη\eta and ϕϕ\phi yields relative to the ωω\omega is observed from p-Be to p-U collisions. |
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