LHCb

Abstract:

Energy flows in deep inelastic electron-proton scattering are investigated at a centre-of-mass energy of 269 GeV for the range Q2 ≥ 10 GeV2 using the ZEUS detector. A comparison is made between events with and without a large rapidity gap between the hadronic system and the proton direction. The energy flows, corrected for detector acceptance and resolution, are shown for these two classes of events in both the HERA laboratory frame and the Breit frame. From the differences in the shapes of these energy flows we conclude that QCD radiation is suppressed in the large-rapidity-gap eents compared to the events without a large rapidity gap. © 1994.

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^νp, inelastic diffractive production, σnd^νp, non-diffractive production, σd^νp, as well as the total cross section, σtot^νp, have been measured at an average υp center of mass energy of 180 GeV with the ZEUS detector at HERA. The resulting values are σel^νp = 18 ± 7 μb, σd^νp = 33 ± 8 μb, σnd^νp = 91 ± 11 μb, and σtot^νp 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.