Search for $B^0_s$-$\overline{B^0_s}$ oscillations in DELPHI using high-$p_t$ leptons

• Published in: The European physical journal. C, Particles and fields Vol. 35; pp. 35 - 52
• 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., 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, 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, P., Checchia, P., Chierici, R., Shlyapnikov, P., Chudoba, J., Chung, U., Cieslik, K., Collins, P., Contri, R., Cosme, G., Cossutti, F., Costa, J., 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., Drees, J., Dris, M.
• Format: Journal Article
• Language: English
• Published: Springer Verlag (Germany) 2004
• Subjects: High Energy Physics - Experiment; Physics
• ISSN: 1434-6044; 1434-6052
• DOI: 10.1140/epjc/s2004-01827-0

Oscillations in the B0_s - anti-B0_s system were studied in events selected from about 4.3 million hadronic Z^0 decays registered by DELPHI between 1992 and 2000. This paper presents updates of two published analyses ([11,12]). The first analysis, which utilizes leptons emitted with large momentum transverse to a jet, was improved by means of a better algorithm for the vertex reconstuction and a new algorithm for flavour-tagging at production time. The second analysis, which utilizes D_s-lepton events, was improved by optimizing the treatment of proper time resolution. No signal of B0_s oscillations was observed and limits on the mass difference between the physical B0_s states were obtained to be: \Delta m_s > 8.0 ps^{-1} at the 95% C.L. with a sensitivity of \Delta m_s = 9.1 ps^{-1} in the high p_t lepton analysis and \Delta m_s > 4.9 ps^{-1} at the 95% C.L. with a sensitivity of \Delta m_s = 8.6 ps^{-1} in the D_s-lepton analysis. Previously published results on these analyses are superseed. The combination of these results with those obtained in other independent analyses previously performed in DELPHI (D_s-hadron, exclusive B0_s, inclusive vertex) gives: \Delta m_s > 8.5 ps^{-1} at the 95% C.L. with a sensitivity of \Delta m_s = 12.0 ps^{-1}.