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Charmonia production in 450 GeV/c proton induced reactions

1998; Elsevier BV; Volume: 444; Issue: 3-4 Linguagem: Inglês

10.1016/s0370-2693(98)01398-7

1873-2445

M.C. Abreu, C. Baglin, A. Baldit, M. Bedjidian, P. Bordalo, A. Bussière, P. Busson, J. Castor, T. Chambon, C. Charlot, B. Chaurand, D. Contardo, E. Descroix, A. Devaux, O. Drapier, B. Espagnon, J. Fargeix, Rui M. L. Ferreira, F. Fleuret, P. Force, L. Fredj, J. Gago, C. Gerschel, P. Gorodetzky, J.Y. Grossiord, A. Guichard, J.P. Guillaud, R. Haroutunian, D. Jouan, L. Kluberg, R. Kossakowski, G. Landaud, C. Lourenço, R. Mandry, F. Malek, J.R. Pizzi, C. Racca, S. Ramos, A. Romana, P. Saturnini, S. Silva, P. Sonderegger, X. Tarrago, J. Varela, F. Vazeille,

Nuclear reactor physics and engineering

Absolute J/ψ and ψ′ production cross sections have been measured at the CERN SPS, with 450 GeV/c protons incident on a set of C, Al, Cu and W targets. Complementing these values with the results obtained by experiment NA51, which used the same beam and detector with H and D targets, we establish a coherent picture of charmonia production in proton-induced reactions at SPS energies. In particular, we show that the scaling of the J/ψ cross section with the mass number of the target, A, is well described as Aα, with αψ=0.919±0.015. The ratio between the J/ψ and ψ′ yields, in our kinematical window, is found to be independent of A, with αψ′−αψ=0.014±0.011.