Intrinsic charm contribution to the proton spin

Polyakov, Maxim V.; Schäfer, Andreas; Teryaev, Oleg

doi:10.1103/physrevd.60.051502

Cited by 41 publications

(42 citation statements)

References 19 publications

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“…Our ∆c in (47) is smaller in magnitude than that given in [5,14] (≃ −0.3). However, the size of ∆c given in [7] (≃ −5 · 10 −4 ) is even smaller. Hence further investigation in this quantity is needed.…”

Section: Numerical Results and Discussionmentioning

confidence: 99%

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Charm antiquark and charm quark in the nucleon

Song¹

2002

Phys. Rev. D

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We estimate the intrinsic charm contributions to the quark flavor and spin observables of the nucleon in the SU(4) quark meson fluctuation model. In this model, the charm or anticharm reside in the charmed mesons created by the nonperturbative quantum quark-meson fluctuations. The intrinsic charm content in the proton, 2c/ (q +q) ≃ 0.011 ± 0.008, is almost one order of magnitude smaller than the intrinsic strange content. The intrinsic charm helicity is also small and negative, ∆c ≃ −(0.009 ± 0.006). The fraction of the total quark helicity carried by the charm is |∆c/∆Σ| ≃ 0.021±0.014. The ratio of the charm with positive helicity to that with negative helicity is c ↑ /c ↓ = 35/67. For the intrinsic strange component, one has s ↑ /s ↓ ≃ 7/13. A detail comparison of our predictions with data and other models or analyses is given. The intrinsic charm contribution to the Ellis-Jaffe sum rule is also discussed.

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Section: Numerical Results and Discussionmentioning

confidence: 99%

“…MIT bag model [2], NJL model [3], meson cloud model [1,4], instanton model [5,6] and others [7], etc.) or combination of the IC hypothesis and analysing the existing DIS data on charm production to obtain some information of the intrinsic charm content (see e.g.…”

Section: Introductionmentioning

confidence: 99%

Charm antiquark and charm quark in the nucleon

Song¹

2002

Phys. Rev. D

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“…The twist-4 matrix element f 2 , (1), also plays a role in the so-called "intrinsic" charm contribution to the nucleon spin [7]. Making use of an expansion in inverse powers of the charm quark mass, 1/m c , Franz et al [8], correcting an earlier results [9,10], related the charm quark contribution to the axial current to the matrix element of the flavor-singlet twist-4 operator, (1).…”

Section: Introductionmentioning

confidence: 99%

Spin-dependent twist-4 matrix elements from the instanton vacuum: Flavor-singlet and nonsinglet

2002

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We estimate the twist-4 spin-1 nucleon matrix element f 2 in an instanton-based description of the QCD vacuum. In addition to the flavor-nonsinglet we compute also the flavor-singlet matrix element, which appears in next-to-leading order of the 1/N c -expansion. The corresponding twist-3 spin-2 matrix elements d 2 are suppressed in the packing fraction of the instanton medium,ρ/R ≪ 1. We use our results to estimate the leading 1/Q 2 power corrections to the first moment of the proton and neutron spin structure functions G 1 , as well as the intrinsic charm contribution to the nucleon spin.

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“…In this scenario, the contribution of intrinsic charm (IC) to the proton PDF (the weight of the relevant Fock state in the proton, see also [7,8,11]) could be as high as 3.5%, with the upper limitation being due to constraints from DIS HERA data. In these models, the probability of finding an intrinsic bottom state (IB) in the proton can also be estimated, but is suppressed by a factor of m 2 c /m 2 b ≃ 0.1 [22] compared to intrinsic charm, where m c and m b are respectively the masses of the charm quark (≃ 1.3 GeV) and of the bottom quark (4.2 GeV).…”

Section: Introductionmentioning

confidence: 99%

Search for intrinsic charm in vector boson production accompanied by heavy-flavor jets

et al. 2015

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Assuming the possible existence of an intrinsic (or valence-like) heavy quark component in the proton distribution functions, we analyze the vector boson Z/W production, accompanied by heavy flavor jets, in pp collisions at the LHC energies. We present theoretical predictions for differential cross sections of such processes and demonstrate their large sensitivity to PDF including an intrinsic charm component to the proton in some kinematical regions. Ratio measurements of the Z+ heavy flavor jets differential cross sections over the corresponding spectra in W + heavy jets events are proposed. These ratios are studied as a function of two different observables that maximize their sensitivity to the intrinsic charm component of the proton: the transverse momentum of the leading heavy flavor jet and the longitudinal momentum fraction x Q F of this jet. Such measurements look very promising for the LHC experiments because they can supply unique information about the intrinsic charm hypothesis.

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Intrinsic charm contribution to the proton spin

Abstract: The charm quark contribution to the first moment of g 1 (x, Q 2 ) is calculated using a heavy mass expansion of the divergence of the singlet axial current. It is shown to be small.

Cited by 41 publications

References 19 publications

Charm antiquark and charm quark in the nucleon

Charm antiquark and charm quark in the nucleon

Spin-dependent twist-4 matrix elements from the instanton vacuum: Flavor-singlet and nonsinglet

Search for intrinsic charm in vector boson production accompanied by heavy-flavor jets

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