A measurement of the partial width ratio GAMMA(bbBAR)/GAMMA(had) using a method which tags the Z --> bbBAR decays through the lifetime of the produced heavy hadrons is presented. This method relies on the tracking precision afforded by a double-sided silicon vertex detector. The tag algorithm makes a probabilistic interpretation of three-dimensional track impact parameters, using the data to measure the resolution. By tagging the two b hadrons separately, both GAMMA(bbBAR)/GAMMA(had) and the tag efficiency can be determined from the data. For a 26% efficiency of tagging a single b hadron within the vertex detector solid angle coverage, a purity of 96% is achieved. A value of GAMMA(bbBAR)/GAMMA(had) = 0.2192+/-0.0022(stat.)+/-0.0026(syst.)+/-0.0016(GAMMA(ccBAR)/GAMMA(had)) is found. Combining this result with other recent ALEPH GAMMA(bbBAR)/GAMMA(had) measurements gives a 95% confidence upper limit on the Standard Model top mass of M(t) < 228 GeV.

A precise measurement of ΓZ-->bb/ΓZ-->hadrons / Buskulic, D., de Bonis, I., Decamp, D., Ghez, P., Goy, C., Lees, J.-P., Minard, M.-N., Pietrzyk, B., Ariztizabal, F., Comas, P., Crespo, J.M., Delfino, M., Efthymiopoulos, I., Fernandez, E., Fernandez-Bosman, M., Gaitan, V., Garrido, Ll., Mattison, T., Pacheco, A., Padilla, C., et al.. - In: PHYSICS LETTERS. SECTION B. - ISSN 0370-2693. - STAMPA. - 313:3-4(1993), pp. 535-548. [10.1016/0370-2693(93)90028-G]

A precise measurement of ΓZ-->bb/ΓZ-->hadrons

Creanza, D.;Iaselli, G.;Maggi, G.;
1993

Abstract

A measurement of the partial width ratio GAMMA(bbBAR)/GAMMA(had) using a method which tags the Z --> bbBAR decays through the lifetime of the produced heavy hadrons is presented. This method relies on the tracking precision afforded by a double-sided silicon vertex detector. The tag algorithm makes a probabilistic interpretation of three-dimensional track impact parameters, using the data to measure the resolution. By tagging the two b hadrons separately, both GAMMA(bbBAR)/GAMMA(had) and the tag efficiency can be determined from the data. For a 26% efficiency of tagging a single b hadron within the vertex detector solid angle coverage, a purity of 96% is achieved. A value of GAMMA(bbBAR)/GAMMA(had) = 0.2192+/-0.0022(stat.)+/-0.0026(syst.)+/-0.0016(GAMMA(ccBAR)/GAMMA(had)) is found. Combining this result with other recent ALEPH GAMMA(bbBAR)/GAMMA(had) measurements gives a 95% confidence upper limit on the Standard Model top mass of M(t) < 228 GeV.
1993
A precise measurement of ΓZ-->bb/ΓZ-->hadrons / Buskulic, D., de Bonis, I., Decamp, D., Ghez, P., Goy, C., Lees, J.-P., Minard, M.-N., Pietrzyk, B., Ariztizabal, F., Comas, P., Crespo, J.M., Delfino, M., Efthymiopoulos, I., Fernandez, E., Fernandez-Bosman, M., Gaitan, V., Garrido, Ll., Mattison, T., Pacheco, A., Padilla, C., et al.. - In: PHYSICS LETTERS. SECTION B. - ISSN 0370-2693. - STAMPA. - 313:3-4(1993), pp. 535-548. [10.1016/0370-2693(93)90028-G]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11589/7594
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