“…MeV for channel (1) and 145.42 ± 0.05 (stat.) MeV for channel (2), in agreement with the PDG value [9]. The width of the signals were σ = 0.68 ± 0.02 MeV and σ = 0.72 ± 0.05 MeV, respectively, in agreement with our MC simulation.…”
supporting
confidence: 88%
“…Here η D * is the pseudorapidity of the D * , defined as − ln(tan(θ/2)), where the polar angle θ is taken with respect to the proton beam direction. 2 The data sample is larger by more than an order of magnitude compared to our previous study [11], which allows an accurate measurement of the differential cross sections in both p D * ⊥ and η D * and thus a more stringent test of the NLO QCD predictions.…”
Section: Introductionmentioning
confidence: 94%
“…At least one combination of tracks detected in the CTD was required to be within wide mass windows around the nominal values in ∆M and in M(Kπ) (M(Kπππ)) for reaction (1) (reaction (2)). In addition, cuts were made on the transverse momenta of tracks associated with these D * candidates and p D * ⊥ was required to be above 1.8 GeV for reaction (1) and above 3.3 GeV for reaction (2). For the measurement of D * in association with jets, an alternative trigger strategy is possible at the TLT, based upon the jets themselves.…”
Section: Experimental Conditionsmentioning
confidence: 99%
“…No particle identification was used, so kaon and pion masses were assigned in turn to each particle in the combination. Transverse momenta of p track ⊥ > 0.5 GeV were required for all tracks of channel (1) and for the track taken to be the kaon for channel (2). Pion candidates in the latter channel were required to have p track ⊥ > 0.…”
Section: Reconstruction Of D * Candidatesmentioning
confidence: 99%
“…The light quark structure of the photon has been extensively studied in photon-photon collisions at e + e − storage rings [1], whilst there is little information at present on the charm content of the photon. HERA jet studies have shown some sensitivity to the gluon content of the photon [2,3], which is still poorly known. In this paper we present a study of charm photoproduction.…”
Inclusive photoproduction of D * ± mesons has been measured for photon-proton centre-of-mass energies in the range 130 < W < 280 GeV and 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.
“…MeV for channel (1) and 145.42 ± 0.05 (stat.) MeV for channel (2), in agreement with the PDG value [9]. The width of the signals were σ = 0.68 ± 0.02 MeV and σ = 0.72 ± 0.05 MeV, respectively, in agreement with our MC simulation.…”
supporting
confidence: 88%
“…Here η D * is the pseudorapidity of the D * , defined as − ln(tan(θ/2)), where the polar angle θ is taken with respect to the proton beam direction. 2 The data sample is larger by more than an order of magnitude compared to our previous study [11], which allows an accurate measurement of the differential cross sections in both p D * ⊥ and η D * and thus a more stringent test of the NLO QCD predictions.…”
Section: Introductionmentioning
confidence: 94%
“…At least one combination of tracks detected in the CTD was required to be within wide mass windows around the nominal values in ∆M and in M(Kπ) (M(Kπππ)) for reaction (1) (reaction (2)). In addition, cuts were made on the transverse momenta of tracks associated with these D * candidates and p D * ⊥ was required to be above 1.8 GeV for reaction (1) and above 3.3 GeV for reaction (2). For the measurement of D * in association with jets, an alternative trigger strategy is possible at the TLT, based upon the jets themselves.…”
Section: Experimental Conditionsmentioning
confidence: 99%
“…No particle identification was used, so kaon and pion masses were assigned in turn to each particle in the combination. Transverse momenta of p track ⊥ > 0.5 GeV were required for all tracks of channel (1) and for the track taken to be the kaon for channel (2). Pion candidates in the latter channel were required to have p track ⊥ > 0.…”
Section: Reconstruction Of D * Candidatesmentioning
confidence: 99%
“…The light quark structure of the photon has been extensively studied in photon-photon collisions at e + e − storage rings [1], whilst there is little information at present on the charm content of the photon. HERA jet studies have shown some sensitivity to the gluon content of the photon [2,3], which is still poorly known. In this paper we present a study of charm photoproduction.…”
Inclusive photoproduction of D * ± mesons has been measured for photon-proton centre-of-mass energies in the range 130 < W < 280 GeV and 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.
A pedagogical introduction to the experimental results on hard photoproduction at HERA is provided. Then the latest results in this field from ZEUS and H1 are reviewed.
We give a pedagogical introduction to hard photoproduction processes at HERA, including the production of jets, hadrons, and prompt photons. Recent theoretical developments in the three areas are reviewed.
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