Daniel Froidevaux

Observation of single isolated electrons of high transverse momentum in events with missing transverse energy at the CERN pp collider

Abstract We report the results of a search for single isolated electrons of high transverse momentum at the CERN p p collider. Above 15 GeV/c, four events are found having large missing transverse energy along a direction opposite in azimuth to that of the high-pT electron. Both the configuration of the events and their number are consistent with the expectations from the process p + p → W ± + anything , with W→e+ν, where W± is the charged Intermediate Vector Boso postulated by the unified electroweak theory.

Evidence for Z0→e+e− at the CERN p collider

Abstract From a search for electron pairs produced in p p collisions at s = 550 GeV we report the observation of eight events which we interpret as resulting from the process p +p→Z 0 + anything, followed by the decay Z0→e++e− or Z0→e++e−+γ, where Z0 is the neutral Intermediate Vector Boson postulated by the unified electroweak theory. We use four of these events to measure the Z0 mass M Z = 91.9 ± 1.3 ± 1.4 (systematic) GeV /c 2 .

Observation of very large transverse momentum jets at the CERN pp collider

The distribution of total tranverse energy ΣET over the pseudorapidity interval −1 < η < 1 and an azimuthal range Δφ=300° has been measured in the UA2 experiment at the CERN pp collider (s = 540 GeV) using a highly segmented total absorption caloriter. In the events with very large ΣET (ΣET⪆60 GeV) most of the transverse energy is found to be contained in small angular regions as expected for high transverse momentum hadron jets. We discuss the properties of a sample of two-jet events with invariant two-jet masses up to 140 GeVc2 and we measure the cross section for inclusive jet production in the range of jet transverse momenta between 15 and 60 GeVc.

Measurements of hyperon semileptonic decays at the CERN Super Proton Synchrotron

Results on five different hyperon semileptonic decays from the WA2 experiment, performed in the CERN SPS charged hyperon beam, have been analysed within the framework of the Cabibbo model. For the first time, the inconsistencies, which inevitably occur when the results from different experiments are combined, have been avoided in these comprehensive fits to high statistics data from a single hyperon decay experiment. Excellent agreement with the basic Cabibbo model has been obtained using the WA2 data either alone or together with neutron lifetime measurements. These results contrast strongly with other recent Cabibbo analyses which have indicated the presence ofSU(3) breaking effects. Including radiative corrections we have obtained the results,F=0.477±0.012,D=0.756±0.011 and sinθc=0.231±0.003. The ratio (D/D+F) is 0.613±0.009, which is close to theSU(6) prediction of 3/5. Using additional information onft values for superallowed nuclear Fermi transitions, an upper limit on the mixing parameter sinθ3 in the Kobayashi-Maskawa six quark scheme has been obtained: |sinθ3|<0.20.

Particle and antiparticle production by 200 GeV/c protons in the charged hyperon beam at the CERN SPS

Abstract A charge hyperon beam has been brought into operation at the CERN SPS. Particles are identified by a DISC Cerenkov counter, and decay products are analysed by a magnetic spectrometer. Cross sections for the inclusive production of π + , K + , p , Σ + , Σ − , ζ − , d, and π − , K − , p , Σ + , Σ − , ζ − , ω − , d in the forward direction have been measured at laboratory momenta between 70 and 130 GeV/ c . This range of momenta corresponds to 0.35 ⩽ x ⩽ 0.66 for an incident proton momentum of 200 GeV/ c . Antihyperon ( Σ − , ζ − , Σ + ) and Σ + and ω − fluxes have been measured for the first time in a hyperon beam. Scaling behaviour is observed when the data are compared with the results from other experiments. The inclusive particle production cross sections have a (1 − x ) n dependence, where n is characteristics of the particle. A search has been made for new particles in the mass range 2–10 GeV/ c 2 . No evidence is found for such particles.

Measurement of production and properties of jets at the CERN\(\bar pp\) collider

AbstractThe production and properties of high transverse momentum hadron jets have been measured in the UA2 experiment at the CERN

Inclusive π0 production at the CERN p-p̄ collider

\bar pp

Straw tube drift-time properties and electronics parameters for the ATLAS TRT detector

Collider