Detailed balance and sea-quark flavor asymmetry of proton

Zhang, Yongjun; Zhang, Bin; Ma, Bo-Qiang

doi:10.1016/s0370-2693(01)01266-7

Cited by 40 publications

(50 citation statements)

References 19 publications

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“…By incorporating QCD evolution they can describe a variety of data. Zhang et al [46,47,48,49,50] constructed a model using the principle of detailed balance without any free parameter, and they obtained Gottfried sum in surprisingly good agreement with the experimental values. Figure 8 shows various theoretical attempts in describing the data ofd(x)/ū(x) andd(x) −ū(x).…”

Section: Ct10mentioning

confidence: 75%

Flavor structure of the nucleon sea

Peng

2003

Eur. Phys. J. A

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We review the current status and future prospects on the subject of flavor structure of the nucleon sea. The flavor structure of the nucleon sea provides unique information on the nonperturbative aspects of strong interactions allowing stringent tests of various models on the partonic structures of the nucleons as well as lattice QCD calculations. The scope of this review covers the unpolarized, polarized, and the transverse-momentum dependent sea-quark distributions of the nucleons. While the main focus of this review is on the physics motivation and recent progress on the subject of the nucleon sea, we also discuss future prospects of addressing some outstanding issues on the flavor structure of the nucleon sea.

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Section: Ct10mentioning

confidence: 75%

Flavor structure of the nucleon sea

Peng

2003

Eur. Phys. J. A

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“…In principle, we reasonably assume that the basic property of the ensemble of the proton does not change with time. As for the detailed balance model, it is presumed that any two nearby quark-gluon Fock states should be balanced with each other [45,48]. We ignore heavier quarks at first.…”

Section: The Balance Modelmentioning

confidence: 99%

Sea quark contents of octet baryons

Shao

Zhang

2010

Physics Letters B

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The flavor asymmetry of the nucleon sea, i.e., the excess of $d\bar{d}$ quark-antiquark pairs over $u\bar{u}$ ones in the proton can be explained by several different models; therefore, it is a challenge to discriminate these models from each other. We examine in this Letter three models: the balance model, the meson cloud model, and the chiral quark model, and we show that these models give quite different predictions on the sea quark contents of other octet baryons. New experiments aimed at measuring the flavor contents of other octet baryons are needed for a more profound understanding of the non-perturbative properties of quantum chromodynamics (QCD).Comment: 15 pages, 2 figures, version in final publicatio

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“…[17] for other references), chiral quark models, in which there is a direct coupling of the pseudoscalar octect mesons to the quarks [18,19], and statistical models [20,21]. In particular, it was shown in the framework of the meson-cloud model that the surrounding pion cloud is, qualitatively, at the origin of the asymmetry of the proton, since the proton can change into a neutron by emitting a π + (ud), as first noted by Thomas [14] and later evaluated by Henley and Miller [22].…”

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confidence: 99%

Flavor asymmetry of sea quarks in the unquenched quark model

Santopinto

Bijker

2010

Phys. Rev. C

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The flavor asymmetry of the nucleon sea is studied in the framework of the unquenched quark model in which the effects of quark-antiquark pairs (uū, dd, and ss) are taken into account via a microscopic, QCD-inspired, quark-antiquark creation mechanism. The inclusion of the qq pairs leads to an excess ofd overū, in agreement with the experimental data for the proton. In addition, the results for the flavor asymmetry of all ground-state octet and decuplet baryons are presented. The isospin symmetry leads to simple relations among the flavor asymmetries of octet and decuplet baryons. The flavor asymmetry of the + hyperon is predicted to be very similar to that of the proton and much larger than that for the 0 hyperon. A comparison with other approaches shows large differences in the predictions for the flavor asymmetries of the hyperons.Introduction. From an experimental point of view, the flavor asymmetry betweenū andd quarks in the proton is now well established [1-8]; for review, see also Refs. [9,10]. It is well known [11,12] that perturbative QCD is not able to account for this asymmetry. In fact, for quark-antiquark pairs created perturbatively, the sea quarks generated by leading twist evolution, i.e., from gluon splitting, are flavor symmetric with the same amount of uū as dd and ss. Thus the flavor asymmetry of the nucleon sea is assumed to have a nonperturbative origin, and since currently it is still a big challenge to perform calculations from the first principles of QCD in the nonperturbative region, one has to try to understand the situation with effective models of hadrons, in terms of constituent quark degrees of freedom and/or meson-baryon degrees of freedom.The flavor content of the nucleon sea provides an important test for models of the nucleon structure. The quark-parton model predicts a flavor symmetric sea that leads to the Gottfried sum rule S G = 1/3 [13], whereas any deviation from this value is an indication of thed/ū asymmetry of the nucleon sea, thus providing a clean evidence of the existence of nonperturbative higher Fock components (such as qqq-qq configurations) in the proton wave function. The first clear evidence of a flavor asymmetric sea and a related violation of the Gottfried sum rule came in 1991 from the New Muon Collaboration (NMC) [1], which was later confirmed in Drell-Yan experiments [4][5][6][7] that probe the ratioū/d, as well as in semi-inclusive deep-inelastic scattering (SIDIS) experiments [8]. All these experiments show evidence that there are morē d quarks in the proton than there areū quarks [10].Many phenomenological models have been applied to the flavor asymmetry of the nucleon sea, e.g., meson-cloud models [14-16] (see Ref.[17] for other references), chiral quark

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Detailed balance and sea-quark flavor asymmetry of proton

Cited by 40 publications

References 19 publications

Flavor structure of the nucleon sea

Flavor structure of the nucleon sea

Sea quark contents of octet baryons

Flavor asymmetry of sea quarks in the unquenched quark model

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