LHCb

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