Search for exclusive charmless B meson decays with the DELPHI detector at LEP
Physics Letters B 357:1-2 (1995) 255-266
Abstract:
Charmless hadronic decays of beauty mesons have been searched for using the data collected with the DELPHI detector at the LEP collider. Several two, three and four-body decay modes have been investigated. Particle identification was used to distinguish the final states with protons, kaons and pions. Three candidate events selected in two-body decay modes are interpreted as evidence for charmless B decays. No excess has been found in higher multiplicity modes and improved upper limits for some of the branching ratios are given. © 1995.Observation of short range three-particle correlations in e+e- annihilations at LEP energies
Physics Letters B 355:1-2 (1995) 415-424
Abstract:
Measurements are presented of short range three-particle correlations in e+e- annihilations at LEP using data collected by the DELPHI detector. At small values of the four-momentum difference, strong three-particle correlations are observed for like-sign (+++ and ---) and for unlike-sign (++- and +--) pion combinations which are not a consequence of two-particle correlations. A possible explanation of the observed effects in like-sign combinations is the existence of higher order Bose-Einstein interference, which significantly changes the particle distributions in jets. © 1995.Inclusive measurements of the K± and p/p production in hadronic Z0 decays
Nuclear Physics, Section B 444:1-2 (1995) 3-26
Abstract:
This analysis, based on a sample of 170000 hadronic Z0 decays, provides a measurement of the K± and p/p differential cross sections which is compared to string- and cluster fragmentation models. The total multiplicities for K± and p/p per hadronic event were found to be: NK = 2.26 ± 0.18 and Np = 1.07 ± 0.14. The positions ξ* of the maxima of the differential cross sections as a function of ξ = ln(1/xp) for K± and p/p were determined to be 2.63 ± 0.07 and 2.96 ± 0.16 respectively. A comparison of the ξ* values for various identified particles measured at LEP with the prediction of the Modified Leading Logarithm Approximation with Local Parton Hadron Duality model has been performed. The measured ξ* position as a function of the hadron mass, after corrections due to particle decays, is in agreement with the model calculation. © 1995.Measurements of the τ polarisation in Z0 decays
Zeitschrift für Physik C Particles and Fields 67:2 (1995) 183-201
Abstract:
A sample of Z0→τ+τ- events observed in the DELPHI detector at LEP in 1991 and 1992 is analysed to measure the τ polarisation in the exclusive decay channels {Mathematical expression}, {Mathematical expression}, πν, ρν and a1ν. The τ polarisation is also measured with an inclusive hadronic analysis which benefits from a higher efficiency and a better systematic precision than the use of the exclusive decay modes. The results have been combined with those published on the 1990 data. A measurement of the τ polarisation as a function of production angle yields the values for the mean τ polarisation 〈P〉τ=-0.148±0.022 and for the Z0 polarisation PZ=-0.136±0.027. These results are used to determine the ratio of vector to axial-vector effective couplings for taus {Mathematical expression}, and for electrons {Mathematical expression}, compatible with e-τ universality. With the assumption of lepton universality, the ratio of vector to axial-vector effective couplings for leptons {Mathematical expression} is obtained, implying a value of the effective weak mixing angle sin2θefflept=0.2320±0.0021 . © 1995 Springer-Verlag.Production of charged particles, KS 0, K±, p and Λ in Z → bb events and in the decay of b hadrons
Physics Letters B 347:3-4 (1995) 447-466