Higher-twist term in inclusive pion production at large transverse momentum

Berger, Edmond L.; Gottschalk, Thomas D.; Sivers, Dennis

doi:10.1103/physrevd.23.99

Cited by 30 publications

(23 citation statements)

References 46 publications

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“…This is different than our approach. If one only keeps the contribution from T one uses the approximation of vacuum saturation to write it in term of the π wave function at leading twist, our approach is equivalent to that in [3]. It is clear that there are no reasons to neglect other contributions and to use the approximation of vacuum saturation.…”

Section: Quark Recombination At Large K T and Twist-4 Effectmentioning

confidence: 99%

“…It is clear that there are no reasons to neglect other contributions and to use the approximation of vacuum saturation. In [3] the results are given by taking asymptotic form of the wave function, where the integration over the momentum fraction as the variable of the wave function is performed analytically. This prevents us from a direct comparison with our results.…”

Section: Quark Recombination At Large K T and Twist-4 Effectmentioning

confidence: 99%

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QCD analysis of quark recombination for leading particle effect

Chang¹,

Ma²,

Si³

2003

Phys. Rev. D

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The quark recombination mechanism is proposed to explain the asymmetry between production rates of D + and of D − in their inclusive productions, and also asymmetries for other charmed hadrons. These asymmetries are observed in experiment and are called as leading particle effects. In this work we give a general analysis for contributions of quark recombination to these asymmetries. The contributions consist of a perturbative-and nonperturbative part. We perform two types of factorization by considering the produced hadron with large transverse momentum and by taking charm quark as a heavy quark, respectively. In the case of large transverse momentum the effect of quark recombination is the standard twist-4 effect. We find that the contributions are parameterized with four nonperturbative functions, defined with four quark operators at twist-4, for initial hadrons without polarization. By taking charm quark as a heavy quark the factorization can be performed with the heavy quark effective theory(HQET). The effect of quark recombination is in general parameterized by eight nonperturbative parameters which are defined as integrals with matrix elements of four quark operators defined in HQET. For unpolarized hadrons in the initial state, the parameters can effectively be reduced to four. Perturbative parts in the two types of factorization are calculated at tree-level.

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Section: Quark Recombination At Large K T and Twist-4 Effectmentioning

confidence: 99%

Section: Quark Recombination At Large K T and Twist-4 Effectmentioning

confidence: 99%

QCD analysis of quark recombination for leading particle effect

Chang¹,

Ma²,

Si³

2003

Phys. Rev. D

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“…Subsequently, techniques were developed for calculating the normalizations of the CIM subprocesses within QCD, and the phenomenological couplings were found to give contributions that were of order 10 3 times too larger (Farrar and Fox, 1980). In Berger, Gottschalk, and Sivers (1981) a similar but more detailed study of the dominant CIM terms was made. Their conclusion was that the CIM terms could have a significant effect in the region of p T < 6 GeV/c with x T > 0.5.…”

Section: Higher Twist Contributionsmentioning

confidence: 99%

“…However, they can become important near the edge of phase space, and their effects have been found in several recent experiments. For example, in high-mass dimuon production by pions the polarization of the dimuon system is predicted to have a strong variation as x F ->1 (Berger and Brodsky, 1979;Berger, 1980aBerger, , 1980b due to the presence of higher twist subprocesses Trq->y*q. Several experiments have now detected this effect (Anderson et al, 1979;Palestini et al, 1985).…”

Section: /7z^(*>e 2)mentioning

confidence: 99%

Large-momentum-transfer production of direct photons, jets, and particles

1987

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The theoretical framework for describing the production of direct photons in hadronic collisions is reviewed. A detailed comparison between the theoretical predictions and existing data is presented along with a critical evaluation of the various sources of theoretical uncertainty. The information available from direct-photon experiments is contrasted with that learned from jet or single-hadron production. Prospects for new types of measurements in future experiments are also presented.

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“…Small values of A and B are expected from non-zero parton motion, as described by Cahn [58] and Levelt-Mulders [59]. In general, any non-zero parton motion effects, be it kinematic or dynamic, are proportional to P t for A, and P 2 t for B, respectively [58][59][60][61].…”

Section: B Transverse Momenta and Azimuthal Anglesmentioning

confidence: 99%

Semi-inclusive charged-pion electroproduction off protons and deuterons: Cross sections, ratios, and access to the quark-parton model at low energies

Asaturyan¹,

Ent²,

Mkrtchyan³

et al. 2012

Phys. Rev. C

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A large set of cross sections for semi-inclusive electroproduction of charged pions (π ± ) from both proton and deuteron targets was measured. The data are in the deep-inelastic scattering region with invariant mass squared W 2 > 4 GeV 2 (up to ≈ 7 GeV 2 ) and range in four-momentum transfer squared 2 < Q 2 < 4 (GeV/c) 2 , and cover a range in the Bjorken scaling variable 0.2 < x < 0.6. The fractional energy of the pions spans a range 0.3 < z < 1, with small transverse momenta with respect to the virtual-photon direction, P 2 t < 0.2 (GeV/c) 2 . The invariant mass that goes undetected, Mx or W ′ , is in the nucleon resonance region, W ′ < 2 GeV. The new data conclusively show the onset of quark-hadron duality in this process, and the relation of this phenomenon to the high-energy factorization ansatz of electron-quark scattering and subsequent quark → pion production mechanisms. The x, z and P 2 t dependences of several ratios (the ratios of favored-unfavored fragmentation functions, charged pion ratios, deuteron-hydrogen and aluminum-deuteron ratios for π + and π − ) have been studied. The ratios are found to be in good agreement with expectations based upon a high-energy quark-parton model description. We find the azimuthal dependences to be small, as compared to exclusive pion electroproduction, and consistent with theoretical expectations based on tree-level factorization in terms of transverse-momentum-dependent parton distribution and fragmentation functions. In the context of a simple model, the initial transverse momenta of d quarks are found to be slightly smaller than for u quarks, while the transverse momentum width of the favored fragmentation function is about the same as for the unfavored one, and both fragmentation widths are larger than the quark widths.

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Higher-twist term in inclusive pion production at large transverse momentum

Cited by 30 publications

References 46 publications

QCD analysis of quark recombination for leading particle effect

QCD analysis of quark recombination for leading particle effect

Large-momentum-transfer production of direct photons, jets, and particles

Semi-inclusive charged-pion electroproduction off protons and deuterons: Cross sections, ratios, and access to the quark-parton model at low energies

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