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 J. C. Peng Physics , 2000, DOI: 10.1016/S0375-9474(01)00491-2 Abstract: Recent deep inelastic scattering and Drell-Yan experiments have revealed a surprisingly large asymmetry between the up and down sea quark distributions in the nucleon. The current status of the flavor asymmetry of the nucleon sea is reviewed. Implications of various theoretical models and possible future measurements are also discussed.
 Physics , 1997, Abstract: The intrinsic quark-antiquark pairs generated by the minimal energy nonperturbative meson-baryon fluctuations in the nucleon sea provide a consistent framework for understanding a number of empirical anomalies observed in the deep inelastic quark-parton structure of nucleons: the flavor asymmetry of the nucleon sea implied by the violation of Gottfried sum rule, the proton spin problem implied by the violation of the Ellis-Jaffe sum rule, and the outstanding conflict between two different determinations of the strange quark sea in the nucleon.
 Revista mexicana de física , 2008, Abstract: the flavor asymmetry of the nucleon sea is discussed in an unquenched quark model for baryons in which the effects of quark-antiquark pairs are taken into account in an explicit form. the inclusion of pairs leads automatically to an excess of over quarks in the proton, in ageement with experimental data.
 High Energy Physics - Phenomenology , 2008, Abstract: The flavor asymmetry of the nucleon sea is discussed in an unquenched quark model for baryons in which the effects of quark-antiquark pairs (u anti-u, d anti-d and s anti-s) are taken into account in an explicit form. The inclusion of q anti-q pairs leads automatically to an excess of anti-d over anti-u quarks in the proton, in agreement with experimental data.
 Physics , 2008, Abstract: The flavor asymmetry of the nucleon sea is discussed in an unquenched quark model for baryons in which the effects of quark-antiquark pairs (u anti-u, d anti-d and s anti-s) are taken into account in an explicit form. The inclusion of q anti-q pairs leads automatically to an excess of anti-d over anti-u quarks in the proton, in agreement with experimental data.
 Physics , 2000, DOI: 10.1142/S0217732300000888 Abstract: A phenomenological ansatz for the flavor-asymmetry of the light sea distributions of the nucleon, based on the Pauli exclusion principle, is proposed. This ansatz is compatible with the measured flavor-asymmetry of the unpolarized sea distributions, $\bar{d}>\bar{u}$, of the nucleon. A prediction for the corresponding polarized flavor-asymmetry is presented and shown to agree with predictions of (chiral quark--soliton) models which successfully reproduced the flavor-asymmetry of the unpolarized sea.
 Physics , 2001, DOI: 10.1016/S0146-6410(01)00155-7 Abstract: A surprisingly large asymmetry between the up and down sea quark distributions in the nucleon has been observed in recent deep inelastic scattering and Drell-Yan experiments. This result strongly suggests that the mesonic degrees of freedom play an important role in the description of the parton distributions of the hadronic sea. In this article, we review the current status of our knowledge of the flavor structure of the nucleon sea. The implications of various theoretical models as well as possible future measurements are also discussed.
 Physics , 2014, DOI: 10.1016/j.ppnp.2014.08.002 Abstract: 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 non-perturbative 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.
 Physics , 1995, Abstract: We study off-shell effects of the pion cloud on the sea quark distribution in the nucleon. The structure function of the off-mass-shell pion is obtained within the Nambu and Jona-Lasinio model, where the shape of the distribution function depends on the pion momentum. By using the momentum dependent pion structure function, the SU(2) flavor asymmetry in the nucleon see is reexamined within the pionic model, in which the sea quark distribution of the nucleon is given as a convolution of the off-shell pion structure function. We calculate experimentally observed quantities related to the SU(2) asymmetry of the nucleon sea such as the Gottfried sum and the Drell-Yan cross section ratios, and find these quantities are insensitive to the off-shell effects of the pions structure function. However, the $x$ dependence of $\bar{u}-\bar{d}$ calculated with the off-shell structure function shows a clear deviation from the result with the on-shell one. We evaluate also the cross section of semi-inclusive lepton-nucleon process with a slow nucleon production to demonstrate the off-shell effect to be checked experimentally.
 Physics , 1996, DOI: 10.1103/PhysRevC.55.900 Abstract: We re-examine the effects of anti-symmetry on the anti-quarks in the nucleon sea arising from gluon exchange and pion exchange between confined quarks. While the effect is primarily to suppress anti-down relative to anti-up quarks, this is numerically insignificant for the pion terms.
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