LHCb

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.

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.

Abstract:

A search for the Standard Model Higgs boson was performed in the data sample of around 1 million hadronic Z0 decays recorded in 1991 and 1992 with the DELPHI detector at LEP. The Higgs boson was searched for through its production in association with either neutrinos, electrons or muons. Four low mass events remain after the selections in the charged leptonic channels, that are likely to be due to background, especially four fermion processes. These results restrict the mass of the Standard Model Higgs boson to be larger than 55.7 GeV/c2 at the 95% confidence level. © 1994.