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Next-to-leading-order predictions for D*± plus jet photoproduction at DESY HERA

Gudrun Heinrich and Bernd A. Kniehl
Phys. Rev. D 70, 094035 – Published 18 November 2004
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  • INTRODUCTION
  • THEORETICAL FRAMEWORK
  • NUMERICAL RESULTS
  • CONCLUSIONS
  • ACKNOWLEDGEMENTS
    • References

    Abstract

    We study the photoproduction of a D*± meson in association with a hadron jet at next-to-leading order in the parton model of QCD with nonperturbative fragmentation functions extracted from LEP1 data of e+e− annihilation. The transverse-momentum and rapidity distributions recently measured at DESY HERA in various kinematic ranges nicely agree with our theoretical predictions. This provides a useful test of the universality and the scaling violations of the fragmentation functions predicted by the factorization theorem. These comparisons also illustrate the significance of the charm component in the resolved photon. This is elaborated by investigating the cross section distributions in xobsγ and cosθ*.

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    • Received 26 September 2004

    DOI:https://doi.org/10.1103/PhysRevD.70.094035

    ©2004 American Physical Society

    Authors & Affiliations

    Gudrun Heinrich

    • II. Institut für Theoretische Physik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany

    Bernd A. Kniehl*

    • Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), Föhringer Ring 6, 80805 Munich, Germany

    • *Permanent address: II. Institut für Theoretische Physik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany

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    Issue

    Vol. 70, Iss. 9 — 1 November 2004

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    Images

    • Figure 1
      Figure 1
      Examples of LO diagrams involving (a) direct photons or (b) the quark or (c) gluon components of resolved photons.Reuse & Permissions
    • Figure 2
      Figure 2
      Examples of NLO diagrams contributing to the real corrections in (a) direct and (b)  resolved photoproduction, and (c) to the virtual corrections in direct photoproduction.Reuse & Permissions
    • Figure 3
      Figure 3
      The differential cross section dσ/dpTj of ep→D*±j+X in photoproduction for −1.5<ηj<2.4, pTD>3  GeV, and |ηD|<1.5 measured by ZEUS [9] is compared with our NLO prediction (solid histogram) including conservative errors (hatched bands). For comparison, the errors due to diagonal scale variation (dotted-dashed and dotted histograms) and the predictionevaluated for central scale choice with the GRV HO photon PDFs (dashed histogram) are also shown.Reuse & Permissions
    • Figure 4
      Figure 4
      Same as in Fig. 3, but for dσ/dηj with pTj>6  GeV.Reuse & Permissions
    • Figure 5
      Figure 5
      Same as in Fig. 4, but for (a) 6<pTj<9  GeV and (b) pTj>9  GeV.Reuse & Permissions
    • Figure 6
      Figure 6
      Same as in Fig. 3, but for (a) −1.5<ηj<−0.5, (b) −0.5<ηj<0.5, (c) 0.5<ηj<1.5, and (d) 1.5<ηj<2.4 and without experimental data.Reuse & Permissions
    • Figure 7
      Figure 7
      Our central NLO prediction of the differential cross section dσ/dxobsγ of ep→D*±j+X in photoproduction for pTD>3  GeV, |ηD|<1.5, pTj>6  GeV, and −1.5<ηj<2.4 (solid histogram) and its direct- (dashed histogram) and resolved-photon (dotted histogram) components.Reuse & Permissions
    • Figure 8
      Figure 8
      Direct- (solid histograms) and resolved-photon (dashed histograms) components of our central NLO predictions of the differential cross sections (a) dσ/dηj for pTD>3  GeV, |ηD|<1.5, and pTj>6  GeV and (b) dσ/dηD for pTD>3  GeV, pTj>6  GeV, and −1.5<ηj<2.4 of ep→D*±j+X in photoproduction.Reuse & Permissions
    • Figure 9
      Figure 9
      Our central NLO prediction of the differential cross section dσ/dηj of ep→D*±j+X in photoproduction for pTD>3  GeV, |ηD|<1.5, and pTj>6  GeV (a) without and (b) with the acceptance cut xobsγ<0.75 (solid histograms) and the evaluations with Fg/γ=0 (dashed histograms) or Fc/γ=0 (dotted histograms).Reuse & Permissions
    • Figure 10
      Figure 10
      Direct- (dashed histogram) and resolved-photon (dot-dashed histogram) contributions as well as contributions with xobsγ>0.75 (dotted histogram) and xobsγ<0.75 (solid histogram) to our central NLO prediction of the differential cross section dσ/dcos* of ep→D*±j+X in photoproduction for pTD>3  GeV, |ηD|<1.5, pTj>6  GeV, and −1.5<ηj<2.4.Reuse & Permissions
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