Measurements of the Z partial decay width into $c\overline{c}$ and multiplicity of charm quarks per b decay

• Published in: The European physical journal. C, Particles and fields Particles and fields, 2000, Vol.12, p.225-241
• Main Authors: Abreu, P., Adam, W., Adye, T., Adzic, P., Azhinenko, I., Albrecht, Z., Alderweireld, T., Alekseev, G.D., Alemany, R., Allmendinger, T., Allport, P.P., Almehed, S., Amaldi, U., Amapane, N., Amato, S., Anassontzis, E.G., Andersson, P., Andreazza, A., Andringa, S., Antilogus, P., Apel, W.D., Arnoud, Y., Asman, B., Augustin, J.-E., Augustinus, A., Baillon, P., Bambade, P., Barao, F., Barbiellini, Guido, Barbier, R., Bardin, D.Yu, Barker, G., Baroncelli, A., Battaglia, M., Baubillier, M., Becks, K.H., Begalli, M., Behrmann, A., Beilliere, P., Belokopytov, Yu, Benekos, N.C., Benvenuti, A.C., Berat, C., Berggren, M., Bertini, D., Bertrand, D., Besancon, M., Bigi, M., Bilenkii, M.S., Bizouard, M.A., Bloch, D., Blom, H.M., Bonesini, M., Bonivento, W., Boonekamp, M., Booth, P.S.L., Borgland, A.W., Borisov, G., Bosio, C., Botner, O., Boudinov, E., Bouquet, B., Bourdarios, C., Bowcock, T.J.V., Boyko, I., Bozovic, I., Bozzo, M., Branchini, P., Brenke, T., Brenner, R.A., Bruckman, P., Brunet, J.M., Bugge, L., Buran, T., Burgsmuller, T., Buschbeck, B., Buschmann, P., Cabrera, S., Caccia, M., Calvi, M., Camporesi, T., Canale, V., Carena, F., Carroll, L., Caso, C., Castillo Gimenez, M.V., Cattai, A., Cavallo, F.R., Chabaud, V., Charpentier, P., Chaussard, L., Checchia, P., Chelkov, G.A., Chierici, R., Shlyapnikov, P., Chochula, P., Chorowicz, V., Chudoba, J., Cieslik, K., Collins, P.
• Format: Article
• Language: English
• Subjects: High Energy Physics - Experiment; Physics
• ISSN: 1434-6044; 1434-6052
• DOI: 10.1007/s100529900228

The partial decay width $R_c$ of the $Z$ into $c\bar{c}$ quark pair and the number of charm quarks $n_c$ per $b$ decay are measured with the DELPHI detector at \mbox{LEP 1}. Particle identification provides clear $D^0$, $D^+$, $D_s^+$ and $\Lambda_c^+$ signatures. The charm hadron production rate is measured in each channel by a fit to the scaled energy, impact parameter information and the invariant mass spectrum. Two measurements of $R_c$ are presented, from the $D^{*+}$ production rate and from the overall charm counting, including strange charm baryon production, in $c\bar{c}$ events. The multiplicity $n_c$, which includes hidden $c\bar{c}$ and strange charm baryon production, is inferred from the charm counting in $b\bar{b}$ events. The final results are $R_c = 0.1665 \pm 0.0095$ and $n_c = 1.166 \pm 0.086$.