The production of very large transverse momentum hadron jets has been measured in the UA2 experiment at the CERN p p Collider for s = 540 GeV using a highly segmented calorimeter. The range of previously available cross sections for inclusive jet production is extended to p T = 150 GeV and the two-jet invariant mass distribution to m jj = 280 GeV with the largely increased data sample collected during the 1983 running period. The results are compared with the predictions of QCD models.
LISTED ERRORS INCLUDE STATISTICAL AND THE PT-DEPENDENT UNCERTAINTIES. THE ADDITIONAL OVERALL SYSTEMATIC UNCERTAINTY IS 45PCT.
LISTED ERRORS INCLUDE STATISTICAL AND THE M-DEPENDENT UNCERTAINTIES. THE ADDITIONAL OVERALL SYSTEMATIC UNCERTAINTY IS 45PCT.
The inclusive jet cross section has been measured in the UA1 experiment at the CERN p p Collider at centre-of-mass energies √ s = 546 GeV and √ s = 630 eV. The cross sections are found to be consistent with QCD predictions, The observed change in the cross section with the centre-of-mass energy √ s is accounted for in terms of x T scaling.
No description provided.
The production of very large transverse momentum ( p T ) hadron jets has been measured in the UA2 experiment at the CERN p p Collider for s =630 GeV . The inclusive jet production cross sections exhibit a p T -dependent increase with respect to the s =546 GeV data from previous Collider runs. This increase can be described both by QCD calculations and by approximate x T =2 p T /√ s scaling. No significant deviation of the data from QCD predictions is observed at very large p T , placing a lower limit on the characteristic scale Λ c of a hypothetical superstrong contact interaction responsible for the binding of preons in the quark ( Λ c >370 GeV at 95% CL).
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We present results on the jet structure observed in multihadronic events produced by e+e− annihilation in the Mark I magnetic detector at SPEAR. The evidence for jet structure and the jet-axis angular distribution are reported. We give inclusive distributions of the hadrons in Feynman x, rapidity, and transverse momentum relative to the jet axis.
Observed particle PT with respect to jet axis for events with three or more detected charged particles.
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We present a study of heavy flavour (charm and beauty) production using data collected with the UA1 detector at the CERN Proton-Antiproton collider at a centre-of-mass energy of 630 GeV for an integrated luminosity of 556 nb−1. This follows our earlier study ofb\(\bar b\) andc\(\bar c\) production in dimuon events and the evidence for mixing betweenB0 and\(\bar B^0 \) states. Properties of an inclusive sample of events containing a muon withpT>6 GeV/c are compared with QCD predictions for heavy flavour production, using the ISAJET Monte Carlo program. The predicted largepT muon yield from heavy flavour production and decay agrees with the data to within 30%. For events with a muon ofpT>10 GeV/c and at least one jet withET>10 GeV, we measure the ratio charm/(charm+beauty) to be (24±8±9)%. We also show that the correlations observed between the two heavy quark jets expected by flavour conservation are consistent with the mixture of lowest and higher order QCD processes. We study in detail the topological and kinematic properties of a subsample of events containing a highpT muon and one or more jets. The good agreement of the theoretical predictions with our data in a region dominated by the production of charm and beauty shows that one of the main background sources to a new heavy quark signature is well understood.
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Numerical values supplied by K.Wacker. Muon spectrum with at least one jet with PT > 12 GeV/c.
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A study of events containing at least four high transverse momentum jets and a search for double parton scattering (DPS) have been performed using data collected with the UA2 detector at the CERN p p Collider (√ s =630 GeV). The results are in good agreement with leading order QCD calculations. A value of σ DPS <0.82 nb at 95% confidence level (CL) is obtained for the DPS cross section.
Data requested from authors.
Uncorrected cross sections.
Upper limit to DPS contribution to 4JET production.
We have investigated the properties of jet production in almost real γγ collisions at √ s =58 GeV with the TOPAZ detector at the TRISTAN e + e − collider. The data were analyzed with a jet-clustering method based on a cone algorithm. The jet rate shows evidence for a hard scattering effect of the hadronic constituents of a photon (resolved photon processes). We have also observed a substantial energy flow in the small-angle region, which is additional evidence for resolved photon processes. We present the transverse momentum dependence of the inclusive jet and two-jet cross sections and compare them with different model predictions.
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We present cross section measurements for inclusive jet production in almost-real photon-photon interactions at TRISTAN using the AMY detector. The results are compared with leading-order QCD calculations for different parameterizations of the parton density in the photon.
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Inclusive photoproduction of D*+- mesons has been measured for photon-proton centre-of-mass energies in the range 130 < W < 280 GeV and a photon virtuality Q^2 < 1 GeV^2. The data sample used corresponds to an integrated luminosity of 37 pb^-1. Total and differential cross sections as functions of the D* transverse momentum and pseudorapidity are presented in restricted kinematical regions and the data are compared with next-to-leading order (NLO) perturbative QCD calculations using the "massive charm" and "massless charm" schemes. The measured cross sections are generally above the NLO calculations, in particular in the forward (proton) direction. The large data sample also allows the study of dijet production associated with charm. A significant resolved as well as a direct photon component contribute to the cross section. Leading order QCD Monte Carlo calculations indicate that the resolved contribution arises from a significant charm component in the photon. A massive charm NLO parton level calculation yields lower cross sections compared to the measured results in a kinematic region where the resolved photon contribution is significant.
Integrated D*+- cross sections from the decay channel (1) AND (2).
Differential cross section, as a function of transverse momentum, from decay channel (1).
Differential cross section, as a function of pseudo-rapidity, from channel (1).
Interactions of the type ep -> eXY are studied, where the component X of the hadronic final state contains two jets and is well separated in rapidity from a leading baryonic system Y. Analyses are performed of both resolved and direct photoproduction and of deep-inelastic scattering with photon virtualities in the range 7.5 < Q^2 < 80 GeV^2. Cross sections are presented where Y has mass M_Y < 1.6 GeV, the squared four-momentum transferred at the proton vertex satisfies |t| < 1 GeV^2 and the two jets each have transverse momentum p^jet_T > 5 GeV relative to the photon direction in the rest frame of X. Models based on a factorisable diffractive exchange with a gluon dominated structure, evolved to a scale set by the transverse momentum p^hat_T of the outgoing partons from the hard interaction, give good descriptions of the data. Exclusive qqbar production, as calculated in perturbative QCD using the squared proton gluon density, represents at most a small fraction of the measured cross section. The compatibility of the data with a breaking of diffractive factorisation due to spectator interactions in resolved photoproduction is investigated.
Transverse momentum distribution for two jet production in photoproduction events (one entry per jet).
Transverse momentum distribution for two jet production in DIS events (one entry per jet).
Differential pseudo rapidity distribution in the lab frame for photoproduction data (one entry per jet).
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