Rapidity-Alignment and $P_T$ Compensation of Particle Pairs in Hadronic $Z^0$ Decays

• Published in: Physics letters. B 2002, Vol.533, p.243-252
• Main Authors: Abdallah, J., Abreu, P., Adam, W., Adzic, P., Albrecht, T., Alderweireld, T., Alemany-Fernandez, R., Allmendinger, T., Allport, P.P., Almehed, S., 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., Baroncelli, A., Battaglia, M., Baubillier, M., Becks, K.H., Begalli, M., Behrmann, A., Bellunato, T., Benekos, N., Benvenuti, A., Berat, C., Berggren, M., Berntzon, L., Bertrand, D., Besancon, M., Besson, N., Bloch, D., Blom, M., Bonesini, M., Boonekamp, M., Booth, P.S.L., Borisov, G., Botner, O., Bouquet, B., Bowcock, T.J.V., Boyko, I., Bracko, M., Brenner, R., Brodet, E., Brodzicka, J., Bruckman, P., Brunet, J.M., Bugge, L., Buschmann, P., Calvi, M., Camporesi, T., Canale, V., Carena, F., Carimalo, C., Castro, N., Cavallo, F., Chapkin, M., Charpentier, P., Checchia, P., Chierici, R., Chliapnikov, P., Chung, S.U., Cieslik, K., Collins, P., Contri, R., Cosme, G., Cossutti, F., Costa, M.J., Crawley, B., Crennell, D., Cuevas, J., d'Hondt, J., Dalmau, J., da Silva, T., 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.
• Format: Article
• Language: English
• Subjects: High Energy Physics - Experiment; Physics
• ISSN: 0370-2693
• DOI: 10.1016/S0370-2693(02)01658-1

Observation is made of rapidity-alignment of \KK and \pp pairs which results from their asymmetric orientation in rapidity, with respect to the direction from primary quark to antiquark. The \KK and \pp data are consistent with predictions from the fragmentation string model. However, the \pp data strongly disagree with the conventional implementation of the cluster model. The non-perturbative process of `gluon splitting to diquarks' has to be incorporated into the cluster model for it to agree with the data. Local conservation of \pT between particles nearby in rapidity (i.e., \pT compensation) is analysed with respect to the thrust direction for \pipix, \KKx, and \pp pairs. In this case, the string model provides fair agreement with the data. The cluster model is incompatible with the data for all three particle pairs. The model with its central premiss of isotropically-decaying clusters predicts a \pT correlation not seen in the data.