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Abstract:

The time dependent mixing of Bd0-Bd0 mesons has been observed by using the correlations between the charge of D* mesons and the weighted mean charge of particles in each hemisphere. From a reconstructed D*± sample corresponding to about 1.7 million hadronic Z0 decays, the mass difference between the two Bd0 mass eigenstates has been measured to be Δm = 0.50±0.12 (stat.) ± 0.06 (syst.) h {combining short stroke overlay}/ps or, converting into eV/c2: Δm = [3.29 ± 0.79 (stat) ± 0.39 (syst.)] 10-4 eV/c2. © 1994.

Abstract:

Photon proton cross sections for elastic light vector meson production, σel^ν±è, inelastic diffractive production, σnd^ν±è, non-diffractive production, σd^ν±è, as well as the total cross section, σtot^ν±è, have been measured at an average Ï…p center of mass energy of 180 GeV with the ZEUS detector at HERA. The resulting values are σel^ν±è = 18 ± 7 μb, σd^ν±è = 33 ± 8 μb, σnd^ν±è = 91 ± 11 μb, and σtot^ν±è 143 ± 17 μb, where the errors include statistical and systematic errors added in quadrature. © 1994 Springer-Verlag.

Abstract:

Kaon production in one prong tau decays has been studied using data collected with the DELPHI detector at the LEP collider. Charged kaons were identified over a large momentum range by the DELPHI barrel Ring Imaging Cherenkov detector. The following branching ratios have been determined: BR(τ→Kντ)=(0.85±0.18)%, BR(τ→Kντ≥0 neutrals)=(1.54±0.24)%, BR(τ→Kντ≥1 neutrals)=(0.69±0.25)%. The result for the exclusive branching ratio is consistent with the Standard Model prediction based on τ-μ-e universality. In addition, tau decay into K*- was studied in the channel K*-→K-π0. The result BR(τ→K*-ντ)×BR(K *-→K-π0)=(0.57±0.23)% was obtained. © 1994.

Abstract:

A total of about 900 000 Z0 → qq decays have been analyzed to measure the B0B0 mixing probability. Two different b tagging techniques have been used: events with two leptons and events with one lepton and one Λ. From a combination of the two methods the average mixing parameter, χ, was determined to be (12.1±1.6(stat.)±0.4(syst.)±0.4(model)%. © 1994.

Abstract:

Events with a large rapidity gap in deep inelastic scattering with Q2 ≥ 10 GeV2 have been studied in the ZEUS detector. The properties of these events with W > 140 GeV are consistent with a leading twist diffractive production mechanism. In the laboratory frame, with ETjet ≥ 4 GeV, 15% of the events are of the 1-jet type with negligible 2-jet production. The single jet is back-to-back in azimuth with the scattered electron. No energy flow is observed between the jet and the proton direction. With a lower jet transverse energy cut 2-jet production is observed both in the laboratory and the γ* p centre-of-mass systems, demonstrating the presence of hard scattering in the virtual photon proton interactions that give rise to large rapidity gap events. © 1994.