Production of $\Xi_c^0$ and $\Xi_b$ in Z decays and lifetime measurement of $\Xi_b

• Published in: The European physical journal. C, Particles and fields Particles and fields, 2005, Vol.44, p.299-309
• Main Authors: Abdallah, J., Abreu, P., Adam, W., Adzic, P., Albrecht, T., Alderweireld, T., Alemany-Fernandez, R., Allmendinger, T., Allport, P., Amaldi, U., Amapane, N., Amato, S., Anashkin, E., Andreazza, A., Andringa, S., Anjos, N., Antilogus, P., Apel, W.-D., Arnoud, Y., Ask, S., Asman, B., Augustin, J.-E., Augustinus, A., Baillon, P., Ballestrero, A., Bambade, P., Barbier, R., Bardin, D., Barker, G.J., Baroncelli, A., Battaglia, M., Baubillier, M., Becks, K.-H., Begalli, M., Behrmann, A., Ben-Haim, E., Benekos, N., Benvenuti, A., Berat, C., Berggren, M., Berntzon, L., Bertrand, D., Besancon, M., Besson, N., Bloch, D., Blom, M., Bluj, M., Bonesini, M., Boonekamp, M., Booth, P.S.L., Borisov, G., Botner, O., Bouquet, B., Bowcock, V., Boyko, I., Bracko, M., Brenner, R., Brodet, E., Bruckman, P., Brunet, J.-M., Bugge, L., Buschmann, P., Calvi, M., Camporesi, T., Canale, V., Carena, F., Castro, N., Cavallo, F., Chapkin, M., Charpentier, Ph, Checchia, P., Chierici, R., Chliapnikov, P., Chudoba, J., Chung, U., Cieslik, K., Collins, P., Contri, R., Cosme, G., Cossutti, F., Costa, M.J., Crennell, D., Cuevas, J., Dalmau, J., Silva, T.Da, da Silva, W., Della Ricca, G., de Angelis, A., de Boer, W., de Clercq, C., de Lotto, B., de Maria, N., de Min, A., de Paula, L., Di Ciaccio, L., Di Simone, A., Doroba, K., Drees, J., Dris, M., Eigen, G.
• Format: Article
• Language: English
• Subjects: High Energy Physics - Experiment; Physics
• ISSN: 1434-6044; 1434-6052
• DOI: 10.1140/epjc/s2005-02388-4

The charmed strange baryon Xi_c^0 was searched for in the decay channel Xi_c^0 -> Xi- pi+, and the beauty strange baryon Xi_b in the inclusive channel Xi_b -> Xi- l- anti-nu X, using the 3.5 million hadronic Z events collected by the DELPHI experiment in the years 1992--1995. The Xi- was reconstructed through the decay Xi- -> Lambda pi-, using a constrained fit method for cascade decays. An iterative discriminant analysis was used for the Xi_c^0 and Xi_b selection. The production rates were measured to be f_{Xi_c^0} x BR(Xi_c^0 -> Xi- pi+)= (4.7 +/- 1.4 (stat.) +/- 1.1 (syst.))10^{-4} per hadronic Z decay, and BR(b -> Xi_b) x BR(Xi_b -> Xi- l- X)= (3.0 +/- 1.0 (stat.) +/- 0.3 (syst.))10^{-4} for each lepton species (electron or muon). The lifetime of the Xi_b baryon was measured to be tau_{Xi_b} = 1.45{^{+0.55}_{-0.43}} (stat.) +/- 0.13 (syst.) ps. A combination with the previous DELPHI lifetime measurement gives tau_{Xi_b} = 1.48{^{+0.40}_{-0.31}} (stat.) +/- 0.12 (syst.) ps.