Coherent description of $D^{*\pm}$ production in $e^+e^-$ and low- $Q^2$  $ep$ collisions

Binnewies, J.; Kniehl, Bernd A.; Krämer, G.

doi:10.1007/s002880050590

Cited by 58 publications

(77 citation statements)

References 19 publications

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“…The coefficient d i→n (x, µ 0 ) at the initial scale µ 0 = 2m c involves only momenta of order m c , and can thus be calculated within NRQCD in powers of α s (µ 0 ). The evolution of the FF D i→H (x, µ 0 ) up to higher fragmentation scales µ = M T is ruled by the timelike Altarelli-Parisi (AP) equations, which may be conveniently solved in x space [17]. The relative importance of the various terms in Eqs.…”

Section: Theoretical Inputmentioning

confidence: 99%

Tevatron-hera colour-octet charmonium anomaly versus higher-order QCD effects

Kniehl

Krämer

1999

Eur. Phys. J. C

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Approximately taking into account the higher-order effects due to multiple-gluon initial-state radiation, we extract from the latest Tevatron data of prompt J/ψ hadroproduction the leading colour-octet matrix elements within the nonrelativistic-QCD (NRQCD) factorization formalism proposed by Bodwin, Braaten, and Lepage. We find that the matrix elements which describe the formation of J/ψ mesons from colour-octet cc pairs in the angular-momentum states 2S+1 L J = 1 S 0 and 3 P J , with J = 0, 1, 2, which are responsible for the excess of the predicted cross section of inelastic J/ψ photoproduction over the existing HERA data at high values of the inelasticity variable z, are significantly reduced. We conclude that it is premature to proclaim a discrepancy between the Tevatron and HERA measurements of inclusive J/ψ production in the NRQCD framework. We also consider J/ψ mesons originating from the radiative feed down of promptly produced χ cJ mesons.

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Section: Theoretical Inputmentioning

confidence: 99%

Tevatron-hera colour-octet charmonium anomaly versus higher-order QCD effects

Kniehl

Krämer

1999

Eur. Phys. J. C

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“…The parameter ε c is related to the heavy quark mass (M c for charm quark) by ε c = Λ 2 /M 2 c and Λ stands for a hadronic scale. The PFF at scale µ > µ 0 can be given by solving the DGLAP equations, which is complicated in numerical calculations and currently there is no parametrization forms available as for the light quark fragmentation function [36]. To simplify the numerical calculations, we choose µ 0 = Q as the first step for numerical calculations and then obtain D D c (z, Q) and D D g (z, Q) according to Eq.…”

Section: The Virtual Corrections In Eq (35) Can Be Obtained Via Unitmentioning

confidence: 99%

“…After considering higher order contributions, the inclusive tensor can be written as [31,[34][35][36][37] …”

Section: Generalized Factorizationmentioning

confidence: 99%

Multiple parton scattering in nuclei: heavy quark energy loss and modified fragmentation functions

Zhang

Wang

2005

Nuclear Physics A

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Multiple scattering, induced radiative energy loss and modified fragmentation functions of a heavy quark in nuclear matter are studied within the framework of generalized factorization in perturbative QCD. Modified heavy quark fragmentation functions and energy loss are derived in detail with illustration of the mass dependencies of the Landau-Pomeranchuk-Migdal interference effects and heavy quark energy loss. Due to the quark mass dependence of the gluon formation time, the nuclear size dependencies of nuclear modification of the heavy quark fragmentation function and heavy quark energy loss are found to change from a linear to a quadratic form when the initial energy and momentum scale are increased relative to the quark mass. The radiative energy loss of the heavy quark is also significantly suppressed due to limited cone of gluon radiation imposed by the mass. Medium modification of the heavy quark fragmentation functions is found to be limited to the large z region due to the form of heavy quark fragmentation functions in vacuum.

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“…On the one hand, at NLO, the cross section dσ/dx of e + e − annihilation becomes negative in the upper x range, at x ∼ > 0.9 [see Fig. 4(a)], where the data is very precise, so that a low-quality fit is obtained unless this x range is excluded by hand [34,35]. On the other hand, the LO and NLO predictions for other types of processes, such as photoproduction in ep scattering [see Fig.…”

Section: Inclusive B-meson Productionmentioning

confidence: 99%

“…The attempt to split the B-meson FFs into a so-called perturbative FF (PFF) and a nonperturbative remainder is interesting in its own right. However, detailed analysis for D * ± -meson FFs [34] revealed that such a procedure leads to deficient results in practical applications. On the one hand, at NLO, the cross section dσ/dx of e + e − annihilation becomes negative in the upper x range, at x ∼ > 0.9 [see Fig.…”

Section: Inclusive B-meson Productionmentioning

confidence: 99%

Hadron Production in Hadron-Hadron and Lepton-Hadron Collisions

Kniehl

2003

Hadron Collider Physics 2002

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Summary. We review a recent global analysis of inclusive single-charged-hadron production in high-energy colliding-beam experiments, which is performed at nextto-leading order (NLO) in the parton model of quantum chromodynamics endowed with nonperturbative fragmentation functions (FFs). Comparisons of pp data from CERN SppS and the Fermilab Tevatron and γp data from DESY HERA with the corresponding NLO predictions allow for quantitative tests of the scaling violations in the FFs and their universality. We emphasize the potential of new measurements at the Tevatron to place tight constraints in the large-x region and on the gluon FF, complementary to those from e + e − data, which are indispensible in order to reliably predict the π 0 background for the H → γγ signal of the intermediate-mass Higgs boson at the Tevatron and the CERN LHC. Adopting a similar theoretical framework for b-hadron production, we show that the notorious excess of the Tevatron data over existing theoretical calculations can be ascribed, at sufficiently large values of pT , to nonperturbative fragmentation effects inadequately included previously.

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Coherent description of $D^{*\pm}$ production in $e^+e^-$ and low- $Q^2$ $ep$ collisions

Cited by 58 publications

References 19 publications

Tevatron-hera colour-octet charmonium anomaly versus higher-order QCD effects

Tevatron-hera colour-octet charmonium anomaly versus higher-order QCD effects

Multiple parton scattering in nuclei: heavy quark energy loss and modified fragmentation functions

Hadron Production in Hadron-Hadron and Lepton-Hadron Collisions

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