Charmonia production in 450 GeV/ c proton induced reactions

• Published in: Physics letters. B 1998-12, Vol.444 (3), p.516-522
• Main Authors: Abreu, M.C., Baglin, C., Baldit, A., Bedjidian, M., Bordalo, P., Bussière, A., Busson, P., Castor, J., Chambon, T., Charlot, C., Chaurand, B., Contardo, D., Descroix, E., Devaux, A., Drapier, O., Espagnon, B., Fargeix, J., Ferreira, R., Fleuret, F., Force, P., Fredj, L., Gago, J., Gerschel, C., Gorodetzky, P., Grossiord, J.Y., Guichard, A., Guillaud, J.P., Haroutunian, R., Jouan, D., Kluberg, L., Kossakowski, R., Landaud, G., Lourenço, C., Mandry, R., Ohlsson-Malek, F., Pizzi, J.R., Racca, C., Ramos, S., Romana, A., Saturnini, P., Silva, S., Sonderegger, P., Tarrago, X., Varela, J., Vazeille, F.
• Format: Article
• Language: English
• Subjects: High Energy Physics - Phenomenology; Physics
• ISSN: 0370-2693; 1873-2445
• DOI: 10.1016/S0370-2693(98)01398-7

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 A α , with α ψ =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 α ψ ′ − α ψ =0.014±0.011.