Strange b baryon production and lifetime in Z decays

• Published in: Physics letters. B Vol. 384; no. 1-4; pp. 449 - 460
• Main Authors: De Bonis, I., Decamp, D., Goy, C., Odier, P., Casado, M.P., Fernandez, E., Juste, A., Perlas, J.A., Sanchez, F., Teubert, F., de Palma, M., Gelao, G., Maggi, G., Marinelli, N., Huang, X., Wang, T., Cattaneo, M., Comas, P., Harvey, J., Lehraus, I., Lutters, G., Martin, E.B., Minten, A., Mir, Ll.M., Pusztaszeri, J.-F., Ranjard, F., Rensing, P., Wachsmuth, H., Wagner, A., Barrès, A., Guicheney, C., Montret, J-C., Hansen, J.B., Nilsson, B.S., Markou, C., Bourdon, P., Valassi, A., Parsons, M.I., Antonelli, A., Campana, P., Chiarella, V., Knowles, I.G., Reeves, P., Teixeira-Dias, P., Hanke, P., Hansper, G., Sommer, J., Beuselinck, R., Cameron, W., Stacey, A.M., Betteridge, A.P., Crawford, G., Finch, A.J., Williams, M.I., Quast, G., Rohne, E., Calvet, D., Konstantinidis, N., Thulasidas, M., Blum, W., Dietl, H., Ganis, G., Gotzhein, C., Rosado-Schlosser, A., Schael, S., Boucrot, J., Choi, Y., Cordier, A., Heusse, Ph, Jacquet, M., Lefrançois, J., Zerwas, D., Calderini, G., Ciocci, M.A., Ciulli, V., Ferrante, I., Forti, F., Gregorio, A., Lusiani, A., Walsh, J., Green, M.G., Strong, J.A., Botterill, D.R., Edgecock, T.R., Wright, A.E., Bloch-Devaux, B., Renardy, J.-F., McNeil, M.A., Taylor, G., Booth, C.N., Newton, W.M., Böhrer, A., Minguet-Rodriguez, J., Rivera, F., Saraiva, P., Feng, Z., Greening, T.C., Pan, Y.B., Wu, Sau Lan, Zobernig, G.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 19.09.1996; Elsevier
• Subjects: High Energy Physics - Experiment; Physics
• ISSN: 0370-2693; 1873-2445
• DOI: 10.1016/0370-2693(96)00925-2

In a data sample of approximately four million hadronic Z decays recorded with the ALEPH detector from 1990 to 1995, a search for the strange b baryon Ξb is performed with a study of Ξ-lepton correlations. Forty-four events with same sign Ξ−ℓ− combinations are found whereas 8.4 are expected based on the rate of opposite sign Ξ−ℓ+ combinations. This significant excess is interpreted as evidence for Ξb semileptonic decays. The measured product branching ratio is Br(b → Ξb) × Br(Ξb → XcXℓ−νℓ) × Br(Xc → Ξ−X′) = (5.4±1.1(stat) ± 0.8(syst)) × 10−4 per lepton species, averaged over electrons and muons, with Xc a charmed baryon. The Ξb lifetime is measured to be τΞb = 1.35−0.28+0.37(stat)−0.17+0.15(syst) ps.