Charm Fragmentation and Dijet Angular Distributions *
نویسنده
چکیده
Charm fragmentation and dijet angular distributions have been measured in D photoproduction at HERA. Charm fragmentation and its property of universality is evaluated in terms of measurement of Pv, the ratio of vector/(vector + pseudoscalar) mesons. Angular distributions of dijets, with at least one of the jets associated with a D meson, have been measured for samples enriched in direct or resolved photon events. The differential cross section shows a steep rise for resolved events in the photon direction, providing strong evidence that the bulk of the resolved photon cross section is due to the charm content of the photon. The shallower rise for direct events as well as for resolved photon events in the proton direction are consistent with the quark exchange diagrams.
منابع مشابه
Open charm production at HERA
Inclusive charm meson production cross sections in the deep inelastic scattering and photoproduction regimes are compared with QCD leading and next-to-leading order (NLO) calculations. The NLO predictions are significantly below the data in some parts of the measured kinematic range. Angular distributions of dijet events with charm show clear evidence for the existence of charm originating from...
متن کاملCharm dijet angular distributions in γp collisions with ZEUS at HERA
Leonid Gladilin ∗ (on behalf of the ZEUS Collaboration) DESY, ZEUS experiment, Notkestr. 85, 22607 Hamburg, Germany E-mail: [email protected] Dijet angular distributions of photoproduction events in which a D meson is produced in association with one of two energetic jets have been measured using an integrated luminosity of 120 pb. The results are compared with predictions from leading-orde...
متن کاملHeavy Flavour Production at Hera
A selection of topics on open heavy quark production at HERA are reviewed here. Measurements of charm fragmentation parameters will be presented together with developments in the study of D di-jet angular distributions. Charm production in deep inelastic scattering (DIS) is also discussed. Finally we deal with recent measurements of b cross sections using impact parameters in both DIS and photo...
متن کاملDijet angular distributions at √ s = 14 TeV
We present a Monte Carlo study of dijet angular distributions at √ s = 14 TeV. First we perform a next-to-leading order QCD study; we calculate the distributions in four different bins of dijet invariant mass using different Monte Carlo programs and different jet algorithms, and we also investigate the systematic uncertainties coming from the choice of the parton distribution functions and the ...
متن کاملDijet angular distributions in photoproduction of charm at HERA
Dijet angular distributions of photoproduction events in which a D meson is produced in association with one of two energetic jets have been measured with the ZEUS detector at HERA, using an integrated luminosity of 120 pb. Differential cross sections as a function of the angle between the charm-jet and the proton-beam direction in the dijet rest frame have been measured for samples enriched in...
متن کامل