Olivier Kaufmann

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The inclusive single and double differential cross-sections for neutral and charged current processes with four-momentum transfer squared É ¾ between ½½¼ and ¿¼ ¼¼¼ Î ¾ and with Bjorken Ü between ¼¼¼¿¾ and ¼ are measured in · Ô collisions. The data were taken with the H1 detector at HERA between 1994 and 1997, and they correspond to an integrated luminosity(More)
Results on J== production in ep interactions in the H1 experiment at HERA are presented. The J== mesons are produced by almost real photons (Q 2 0) and detected via their leptonic decays. The data have been taken in 1994 and correspond to an integrated luminosity of 2:7 pb ?1. The p cross section for elastic J== production is observed to increase strongly(More)
The elastic electroproduction of mesons is studied at HERA with the H1 detector for a photon virtuality in the range ½ É ¾ ¼ Î ¾ and for a hadronic centre of mass energy in the range ¿¼ Ï ½½¼ GeV. The shape of the () mass distribution in the resonance region is measured as a function of É ¾. The full set of spin density matrix elements is determined, and(More)
Measurements of ep scattering with squared 4{momentum transfer Q 2 up to 35000 GeV 2 are compared with the expectation of the standard deep-inelastic model of lepton{nucleon scattering (DIS). For Q 2 > 15000 GeV 2 , N obs = 12 neutral current candidate events are observed where the expectation is N DIS = 4:71 0:76 events. In the same Q 2 range, N obs = 4(More)
Transverse momentum spectra of charged particles produced in deep inelastic scattering are measured as a function of the kinematic variables x and Q 2 using the H1 detector at the ep collider HERA. The data are compared to diierent parton emission models, either with or without ordering of the emissions in transverse momentum. The data provide evidence for(More)
A search for events with an imbalance in transverse momentum and with isolated high energy leptons has been carried out at the positron-proton collider HERA. One event with an e ? and five events with a are found together with evidence for undetected particles carrying transverse momentum. Within the Standard Model the dominant origin of events with this(More)
The total cross sections for the elastic electroproduction of % and J== mesons for Q 2 > 8 GeV 2 and hWi ' 90 GeV=c 2 are measured at HERA with the H1 detector. The measurements are for an integrated electron?proton luminosity of ' 3 pb ?1. The dependences of the total virtual photon?proton (p) cross sections on Q 2 , W and the momentum transfer squared to(More)
Jet event rates in deep inelastic ep scattering at HERA are investigated applying the modiied JADE jet algorithm. The analysis uses data taken with the H1 detector in 1994 and 1995. The data are corrected for detector and hadronization eeects and then compared with perturbative QCD predictions using next-to-leading order calculations. The strong coupling(More)
Using the H1 detector at HERA, charged particle multiplicity distributions in deep in-elastic e + p scattering have been measured over a large kinematical region. The evolution with W and Q 2 of the multiplicity distribution and of the multiplicity moments in pseu-dorapidity domains of varying size is studied in the current fragmentation region of the(More)