Measurement of the rate of [formula omitted] events in hadronic Z decays and the extraction of the gluon splitting into [formula omitted]

• Published in: Physics letters. B 1999-09, Vol.462 (3), p.425-439
• Main Authors: Almehed, S., Andreazza, A., Arnoud, Y., Augustin, J-E., Ballestrero, A., Begalli, M., Bonesini, M., Boonekamp, M., Botner, O., Bugge, L., Calvi, M., Camporesi, T., Cattai, A., Chaussard, L., Chochula, P., Collins, P., Crepe, S., Dijkstra, H., Ekspong, G., Erzen, B., Espirito Santo, M., Fichet, S., Fuster, J., Gavillet, Ph, Gil, I., Gonzalez Caballero, I., Gouz, Yu, Hamacher, K., Harris, F.J., Heising, S., Herr, H., Heuser, J.-M., Holmgren, S-O., Huet, K., Jackson, J.N., Jarlskog, Ch, Jean-Marie, B., Jonsson, P., Koratzinos, M., Kubinec, P., Lapin, V., Laugier, J-P., Leisos, A., Lemonne, J., Lethuillier, M., Lopez-Fernandez, R., Loukas, D., MacNaughton, J., Malmgren, T.G.M., Mandl, F., Masik, J., Mc Nulty, R., Meyer, W.T., Mirabito, L., Mitaroff, W.A., Moch, M., Monge, M.R., Mulet-Marquis, C., Muryn, B., Navarria, F.L., Neufeld, N., Nikolenko, M., Nomokonov, V., Nygren, A., Obraztsov, V., Onofre, A., Orazi, G., Palacios, J., Phillips, H.T., Piotto, E., Pol, M.E., Privitera, P., Renton, P.B., Richard, F., Ridky, J., Roudeau, P., Ruiz, A., Salt, J., Schneider, H., Sekulin, R., Sheridan, A., Simard, L., Simonetto, F., Sisakian, A.N., Squarcia, S., Stocchi, A., Stugu, B., Szeptycka, M., Tabarelli, T., Timmermans, J., Tinti, N., Trochimczuk, M., Troncon, C., Vallazza, E., Vollmer, C., Vrba, V., Weiser, C., Winter, M., Wolf, G., Zumerle, G.
• Format: Article
• Language: English
• ISSN: 0370-2693; 1873-2445
• DOI: 10.1016/S0370-2693(99)00905-3

The rate Z→ b b ̄ b b ̄ was measured using about 2×10 6 hadronic decays collected by the DELPHI experiment in 1994 and 1995. Events were forced into 3-jets with y min>0.06 and a b-tag was required for every jet. The rate was measured to be: R 4 b = BR( Z→ b b ̄ b b ̄ ) BR( Z →hadrons) =(6.0±1.9 (stat.)±1.4 (syst.))×10 −4 where the invariant mass of every b b ̄ system is above twice the b quark mass. Using the value of R 4b the probability of secondary production of a b b ̄ pair from a gluon per hadronic Z decay, g bb, was extracted and found to be: g bb=(3.3±1.0(stat.)±0.8(syst.))×10 −3.