“…The delta-function model assumes that the charmed quark coalesces with a low-x spectator sea quark or a low momentum secondary quark such that the charmed quark retains its momentum [18]. This model is more consistent with low p T charmed hadroproduction data [25,26,27] than Peterson fragmentation.…”
Fermilab experiment E791, measuring charmed hadron production in π − A interactions at 500 GeV with high statistics, has observed a strong asymmetry between the hadroproduction cross sections for leading D mesons which contain projectile valence quarks and the nonleading charmed mesons without projectile valence quarks. Such correlations of the charge of the D meson with the quantum numbers of the beam hadron explicitly contradict the factorization theorem in perturbative QCD which predicts that heavy quarks hadronize through a jet fragmentation function that is independent of the initial state. The E791 experiment also measures Λ c /Λ c and D s /D s production asymmetries as well as asymmetries in DD pair production. We examine these asymmetries and the fractional longitudinal momentum, x F , distributions for single and pairs of charmed hadrons within a two-component model combining leading-twist gg and qq fusion subprocesses with charm production from intrinsic heavy quark Fock states. A key feature of this analysis is intrinsic charm coalescence, the process by which a charmed quark in the projectile's Fock state wavefunction forms charmed hadrons by combining with valence quarks of similar rapidities.
“…The delta-function model assumes that the charmed quark coalesces with a low-x spectator sea quark or a low momentum secondary quark such that the charmed quark retains its momentum [18]. This model is more consistent with low p T charmed hadroproduction data [25,26,27] than Peterson fragmentation.…”
Fermilab experiment E791, measuring charmed hadron production in π − A interactions at 500 GeV with high statistics, has observed a strong asymmetry between the hadroproduction cross sections for leading D mesons which contain projectile valence quarks and the nonleading charmed mesons without projectile valence quarks. Such correlations of the charge of the D meson with the quantum numbers of the beam hadron explicitly contradict the factorization theorem in perturbative QCD which predicts that heavy quarks hadronize through a jet fragmentation function that is independent of the initial state. The E791 experiment also measures Λ c /Λ c and D s /D s production asymmetries as well as asymmetries in DD pair production. We examine these asymmetries and the fractional longitudinal momentum, x F , distributions for single and pairs of charmed hadrons within a two-component model combining leading-twist gg and qq fusion subprocesses with charm production from intrinsic heavy quark Fock states. A key feature of this analysis is intrinsic charm coalescence, the process by which a charmed quark in the projectile's Fock state wavefunction forms charmed hadrons by combining with valence quarks of similar rapidities.
“…Muchos experimentos han medido la sección eficaz total de charm principalmente para los haces de protones y π, los experimentos con el haz de protones son NA32, NA27, E743, E653, E769, y HERA-B [1,2,3,4,5,6], respectivamente, los experimentos XXXVIII Introducción y Motivación para el haz de π son NA27 [7], NA32 [1,8], E653 [9], E769 [5], WA92 [10], y E791 [11], muchos de estos resultados son sólo para los mesones D (cargados y neutrales). Pero para obtener la sección eficaz total de charm además de sumar los valores obtenidos de los mesones D (neutrales y cargados), se tienen que tomar en cuenta la producción de otros hadrones con charm (D s , Λ c y otros bariones charm).…”
“…Some years ago a simple non-perturbative mechanism of leading charmed mesons production was considered [3] for data analysis of CERN experiment on D-mesons production in π − p-collisions [4]. It was demonstrated that presence of a valence quark from the initial pion (so-called leading quark state) in the final charmed meson is a necessary but insufficient condition for the meson to be a leading one.…”
mentioning
confidence: 99%
“…This formula was used for fixing distribution functions f π vi by means of comparison with the data on leading D-meson production in π − p-collisions at √ s = 26 GeV [4].…”
It is shown that the D-meson, whose light quark is the initial-pion valence quark and whose charmed quark is produced in annihilation of valence quarks and has got a large enough momentum, is really a leading meson in reactions like π − p → DX. If such annihilation of valence quarks from initial hadrons is impossible there must be no distinct leading effect.
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