Physics of the Nucleon Sea Quark Distributions

Abstract

Sea quark distributions in the nucleon have naively been expected to be generated perturbatively by gluon splitting. In this case, there is no reason for the light quark and anti-quark sea distributions to be different. No asymmetries in the strange or heavy quark sea distributions are predicted in the improved parton model. However, recent experiments have called these naive expectations into question. A violation of the Gottfried sum rule has been measured in several experiments, suggesting that $\bar{u}<\bar{d}$ in the proton. Additionally, other measurements, while not definitive, show that there may be an asymmetry in the strange and anti-strange quark sea distributions. These effects may require nonperturbative explanations. In this review we first discuss the perturbative aspects of the sea quark distributions. We then describe the experiments that could point to nonperturbative contributions to the nucleon sea. Current phenomenological models that could explain some of these effects are reviewed.

arXiv comment83 pages LaTeX, 28 .eps figures, style files included

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Cited by in corpus (8)

• Strange quark suppression from a simultaneous Monte Carlo analysis of parton distributions and fragmentation functions
• Novel Phenomenology of Parton Distributions from the Drell-Yan Process
• Light-Cone Models for Intrinsic Charm and Bottom
• Massive charged-current coefficient functions in deep-inelastic scattering at NNLO and impact on strange-quark distributions
• On the extraction of the intrinsic light-quark sea in the proton
• Collinear parton distributions and the structure of the nucleon sea in a light-front meson-cloud model
• Intrinsic light and strange quark--antiquark pairs in the proton and nonperturbative strangeness suppression
• A determination of the flavor asymmetric sea quarks in the proton