J/ ψ production in the hadronic decays of the Z

• Published in: Physics letters. B Vol. 341; no. 1; pp. 109 - 122
• Main Authors: Abreu, P., Ajinenko, I., Aleksan, R., Almehed, S., Almeida, F.M.L., Amaldi, U., Åsman, B., Berggren, M., Bjarne, J., Bocci, V., Bosworth, S., Braibant, S., Brand, K.D., Bruckman, P., Buran, T., Cankocak, K., Cases, R., Caso, C., Cerrito, L., Chorowicz, V., Crosetti, G., Czellar, S., Dalmagne, B., Dam, M., Daum, A., Da Silva, W., Delpierre, P., De Boeck, H., Dijkstra, H., Djama, F., Dufour, Y., Dupont, F., Ehret, R., Ekspong, G., Espirito Santo, M., Foeth, H., Frodesen, A.G., Fruhwirth, R., Gaspar, C., Gavillet, Ph, Gele, D., Grosdidier, G., Guy, J., Hahn, S., Hallgren, A., Hamacher, K., Hao, W., Hernandez, J.J., Herr, H., Hessing, T.L., Higon, E., Holthuizen, D., Jarlskog, G., Katsoufis, E.C., Klovning, A., Koch-Mehrin, A., Kouznetsov, O., Krammer, M., Kronkvist, I., Laktineh, I., Ledroit, F., Lieb, E., Marco, J., Marti, S., Martinez-Vidal, F., Mazzucato, M., Mitaroff, W.A., Mitselmakher, G.V., Murray, W.J., Nielsen, B.S., Normand, A., Orava, R., Osterberg, K., Parodi, F., Perrotta, A., Piana, G., Polok, G., Rahmani, H., Read, A.L., Regler, M., Reid, D., Richard, F., Ronchese, P., Rosso, E., Seitz, A., Sekulin, R., Simonetto, F., Stepaniak, K., Szczekowski, M., Timofeev, V.G., Transtromer, G., Trischuk, W., Tristram, G., Uvarov, V., Vander Velde, C., Van Dam, P., Vaz, P., Wehr, A., Wetherell, A.M., Woschnagg, K.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 22.12.1994; Elsevier
• Subjects: High Energy Physics - Experiment; Physics
• ISSN: 0370-2693; 1873-2445
• DOI: 10.1016/0370-2693(94)01385-3

J/ ψ mesons have been reconstructed from their decay to μ + μ − and e + e −, using the data collected by the DELPHI experiment during 1991 and 1992 at the LEP collider. From about 1 million hadronic Z decays 153 ± 17 J/ ψ were found, 5.4 ± 2.3 ψ′ were obtained in the channel J/ ψ (→ μ + μ −) π + π − and 6.4 ± 2.7 χ c in the channel J/ ψ ( → μ + μ −) γ. As the dominant source of Jψ mesons is from bquarks, the following branching ratios: Br( b → J/ ψ X) = (1.12 ± 0.12 (stat) ± 0.10 (syst.))%, Br( b → ψ′ X) = (0.48 ± 0.22 (stat.± 0.10 (syst.))%, Br( b → χ c1 X) = (1.4 ± 0.6 (stat.) −0.2 +0.4 (syst.))% were measured. From the proper time distribution of the J/ ψ sample, the average lifetime of b-hadrons decaying into J/ ψ was found to be: τ B = 1.50 −0.21 +0.24 (stat.) ± 0.03 (syst.) ps. A search for completely reconstructed B meson decays to final states including a J/ ψ gave a signal of 15 ± 5 events.