Study of charm photoproduction mechanisms

Alvarez, M.; Barate, R.; Blöch, D.; Bonamy, P.; Borgeaud, P.; Burchell, M. J.; Burmeister, H.; Brunet, J. M.; Calviño, F.; Cattaneo, M.; Crespo, J.M.; Dalmagne, B.; David, M.; Ciaccio, L. Di; Druet, P.; Duane, A.; Engel, J. P.; Ferrer, A.; Filippas, T. A.; Fokitis, E.; Forty, R.; Foucault, P.; Gazis, E. N.; Gerber, J.; Giomataris, Y.; Hall, G.; Hofmokl, T.; Katsoufis, E.; Koratzinos, M.; Krafft, C.; Lefièvre, B.; Lemoigne, Y.; López, A.; Lui, Wei; Magneville, C.; Maltezos, A.; McEwen, J.G.; Papadopoulou, Th. D.; Pattison, B.; Poutot, D.; Primout, M.; Rahmani, H.; Roudeau, P.; Seez, C.; Six, J.; Strub, R.; Treille, D.; Triscos, P.; Tristram, G.; Villet, G.; Volte, A.; Wayne, M.; Websdale, D.; Wormser, G.; Zolnierowski, Y.

doi:10.1007/bf01650430

Cited by 29 publications

(6 citation statements)

References 31 publications

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“…The data correspond to the total charm photoproduction cross section from [1] (reverse triangle), [2] (square), [3] (asterisk), [4] (star), [5] (triangles), [6] (circle), following coupling constants:…”

Section: Three Possible Scenariosmentioning

confidence: 99%

“…Since then, several experiments were devoted to this subject, [3,4,5], but, up to now, the smallest energy where data are available is E γ =20 GeV, [6], which is still relatively far from threshold (for example, E thr = 8.7 GeV for γ + p → Λ + c + D 0 ). Charm particle photoproduction is usually interpreted according to the photon-gluon fusion mechanism (PGF), γ+G → c+c [7], which can be considered as the simplest QCD hard process (called leading order (LO) approximation).…”

Section: Introductionmentioning

confidence: 99%

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Polarization phenomena in open charm photoproduction processes

Tomasi–Gustafsson

Rekalo

2004

Phys. Rev. D

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We analyze polarization effects in associative photoproduction of pseudoscalar (D) charmed mesons in exclusive processes γ + N → Yc + D, Yc = Λ + c , Σc. Circularly polarized photons induce nonzero polarization of the Yc-hyperon with x-and z-components (in the reaction plane) and non vanishing asymmetries Ax and Az for polarized nucleon target. These polarization observables can be predicted in model-independent way for exclusive D-production processes in collinear kinematics. The T-even Yc-polarization and asymmetries for non-collinear kinematics can be calculated in framework of an effective Lagrangian approach. The depolarization coefficients D ab , characterizing the dependence of the Yc-polarization on the nucleon polarization are also calculated.

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Section: Three Possible Scenariosmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Polarization phenomena in open charm photoproduction processes

Tomasi–Gustafsson

Rekalo

2004

Phys. Rev. D

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“…The interaction of the virtual photon with intrinsic charm [11][12][13] is one possible competing mechanism. The associated production of Λ cD 0 [14] or, more generally, asymmetric hadronization of c andc like in the Dual Parton model with a meson and a baryon string [15,16] may play an important role in some regions of phase space. A study of the phase space distributions and semi-inclusive differential cross-sections of the D 0 and D * mesons within the acceptance of the COMPASS spectrometer may yield information about the contributions of different production mechanisms [17].…”

Section: Introductionmentioning

confidence: 99%

“…Prior to COMPASS, this energy range was covered only by the EMC experiment [21], which collected about 90 D 0 meson events produced by deep inelastic scattering of 240 or 280 GeV muons on hydrogen and deuterium targets for a study of the charm production mechanism. Only one charm photo-production experiment explored the region close to threshold [22], while two concentrated on high energy photons [16,23].…”

Section: Introductionmentioning

confidence: 99%

D ∗ and D meson production in muon nucleon interactions at 160 GeV/c

Adolph¹,

Michigami²,

Wiślicki³

et al. 2012

Eur. Phys. J. C

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The production of D * and D mesons in inelastic scattering of 160 GeV/c muons off a 6 LiD target has been investigated with the COMPASS spectrometer at CERN for 0.003 (GeV/c) 2 < Q 2 < 10 (GeV/c) 2 and 3 × 10 −5 < x B j < 0.1. The study is based on 8100 events where a D 0 orD 0 is detected subsequently to a D * + or D * − decay, and on 34000 events, where only a D 0 orD 0 is detected. Kinematic distributions of D * , D and K * 2 (1430) are given as a function of their energy E, transverse momentum p T , energy fraction z, and of the virtual photon variables ν, Q 2 and x B j . Semi-inclusive differential D * production cross-sections are compared with theoretical predictions for D * production via photon-gluon fusion into open charm. The total observed production cross-section for D * ± mesons with laboratory energies between 22 and 86 GeV is (1.9 ± 0.4) nb. Significant cross-section asymmetries are observed between D * + and D * − production for ν < 40 GeV and z > 0.6.

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“…Smaller asymmetries are also observed even when there is no leading particle effect. Examples include fixed-target photoproduction [11,12,13], where the beam has no valence quark quantum numbers, the production of D s mesons in fixed-target hadroproduction experiments with π or p beams, and Λ c production in experiments with π − beams. In the last case, there is no asymmetry from the leading particle effect because the Λ + c shares a d quark with the π − while the Λ − c shares aū with the π − .…”

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confidence: 99%

Charm production asymmetries from heavy-quark recombination

Mehen¹

2004

AIP Conference Proceedings

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Abstract. Charm asymmetries in fixed-target hadroproduction experiments are sensitive to power corrections to the QCD factorization theorem for heavy quark production. A power correction called heavy-quark recombination has recently been proposed to explain these asymmetries. In heavy-quark recombination, a light quark or antiquark participates in a hard scattering which produces a charm-anticharm quark pair. The light quark or antiquark emerges from the scattering with small momentum in the rest frame of the charm quark, and together they hadronize into a charm particle. The cross section for this process can be calculated within perturbative QCD up to an overall normalization. Heavy-quark recombination explains the observed D meson and Λ c asymmetries with a minimal set of universal nonperturbative parameters.In this talk I will discuss asymmetries in the production of charm particles in fixedtarget hadroproduction experiments [1,2,3,4,5]. These asymmetries are much larger than predicted by perturbative QCD calculations, so they are a sensitive probe of nonperturbative aspects of heavy particle production. Asymmetries in the production of light particles such as pions and kaons have also been observed, but the production of particles containing heavy quarks is under better theoretical control. When the mass of the quark is heavier than Λ QCD , as is the case for charm, perturbative QCD can be applied even when the particle is produced without large transverse momentum. In addition, nonperturbative effects can be organized in an expansion in Λ QCD /m c .The differential cross-section for the production of a charm particle, H, in the collision of two hadrons, A and B, is believed to factorize in the following manner [6] Here i, j denote partons, f i/A and f j/B are parton distribution functions, D c→H is the fragmentation function for c hadronizing into H and dσ[ij → cc + X] is a perturbatively calculable short-distance cross section. The ellipsis represents corrections to the factorized form of the cross section that are suppressed by Λ QCD /m c , or possibly Λ QCD /p ⊥ if p ⊥ ≫ m c . †

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Study of charm photoproduction mechanisms

Cited by 29 publications

References 31 publications

Polarization phenomena in open charm photoproduction processes

Polarization phenomena in open charm photoproduction processes

D ∗ and D meson production in muon nucleon interactions at 160 GeV/c

Charm production asymmetries from heavy-quark recombination

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