The Sea of Quarks and Antiquarks in the Nucleon: a Review

Abstract

The quark and gluon structure of the proton has been under intense experimental and theoretical investigation for five decades. Even for the distributions of the well-studied valence quarks, challenges such as the value of the down quark to up quark ratio at high fractional momenta remain. Much of the sea of quark-antiquark pairs emerges from the splitting of gluons and is well described by perturbative evolution in quantum chromodynamics. However, experiments confirm that there is a non-perturbative component to the sea that is not well understood and hitherto has been difficult to calculate with ab initio non-perturbative methods. This non-perturbative structure shows up, perhaps most directly, in the flavor dependence of the sea antiquark distributions. While some of the general trends can be reproduced by models, there are features of the data that do not seem to be well described. This article discusses the experimental situation, the status of calculations and models, and the directions where these studies will progress in the near future.

arXiv comment17 pages, 14 figures

References in corpus (72)

• New Generation of Parton Distributions with Uncertainties from Global QCD Analysis
• Parton distributions for the LHC Run II
• New parton distributions for collider physics
• New parton distribution functions from a global analysis of quantum chromodynamics
• Global QCD Analysis of Parton Structure of the Nucleon: CTEQ5 Parton Distributions
• Instantons in QCD
• Parton Physics on Euclidean Lattice
• Final-State Interactions and Single-Spin Asymmetries in Semi-Inclusive Deep Inelastic Scattering
• Improved Measurement of the $\bar{d}/\bar{u}$ Asymmetry in the Nucleon Sea
• A first unbiased global NLO determination of parton distributions and their uncertainties
• Extraction of Spin-Dependent Parton Densities and Their Uncertainties
• A first unbiased global determination of polarized PDFs and their uncertainties
• A determination of parton distributions with faithful uncertainty estimation
• Quark helicity distributions in the nucleon for up, down, and strange quarks from semi--inclusive deep--inelastic scattering
• Precise Measurement of Dimuon Production Cross-Sections in muon neutrino Fe and muon antineutrino Fe Deep Inelastic Scattering at the Tevatron
• Parton distributions and lattice QCD calculations: a community white paper
• Flavor Asymmetry of Antiquark Distributions in the Nucleon
• First simultaneous extraction of spin-dependent parton distributions and fragmentation functions from a global QCD analysis
• Soft-Gluon Resummation and the Valence Parton Distribution Function of the Pion
• Flavor Structure of the Nucleon Sea from Lattice QCD
• Short Range Correlations and the EMC Effect
• Precision measurement and interpretation of inclusive $W^{+}$, $W^{-}$ and $Z/{\gamma }^{\ast }$ production cross sections with the ATLAS detector
• Parton distributions with small-x resummation: evidence for BFKL dynamics in HERA data
• A Lattice Calculation of Parton Distributions
• The Flavor Asymmetry of the Light Quark Sea from Semi-inclusive Deep-inelastic Scattering
• A complete non-perturbative renormalization prescription for quasi-PDFs
• Renormalization in Large Momentum Effective Theory of Parton Physics
• Reconstruction of light-cone parton distribution functions from lattice QCD simulations at the physical point
• Unpolarized and polarized quark distributions in the large-Nc limit
• Chiral extrapolation of lattice moments of proton quark distributions
• Quark helicity distributions from longitudinal spin asymmetries in muon-proton and muon-deuteron scattering
• The pion parton distribution function in the valence region
• Transversity parton distribution functions from lattice QCD
• Flavor Asymmetry of Light Quarks in the Nucleon Sea
• dbar/ubar Asymmetry and the Origin of the Nucleon Sea
• First extraction of valence transversities in a collinear framework
• New limits on intrinsic charm in the nucleon from global analysis of parton distributions
• Measurement of the transverse single-spin asymmetry in $p^{\uparrow }+p\to W^{\pm }/Z^0$ at RHIC
• The Strange Parton Distribution of the Nucleon: Global Analysis and Applications
• Improved Parton Distribution Functions at Physical Pion Mass
• Dynamical Symmetry Breaking in the Sea of the Nucleon
• Isovector unpolarized quark distribution in the nucleon in the large-N_c limit
• The asymptotic behaviour of parton distributions at small and large $x$
• The statistical parton distributions: status and prospects
• Flavor Structure of the Nucleon Sea
• New developments in the statistical approach of parton distributions: tests and predictions up to LHC energies
• Multiplicities of charged pions and unidentified charged hadrons from deep-inelastic scattering of muons off an isoscalar target
• Connection between the Sivers function and the anomalous magnetic moment
• Kinematics of Current Region Fragmentation in Semi-Inclusive Deeply Inelastic Scattering
• Reevaluation of the parton distribution of strange quarks in the nucleon
• Multiplicities of charged kaons from deep-inelastic muon scattering off an isoscalar target
• A Possible Resolution of the Strange Quark Polarization Puzzle ?
• Leading neutron energy and pT distributions in deep inelastic scattering and photoproduction at HERA
• The Flavor Asymmetry of the Nucleon Sea
• Detailed Balance and Sea-Quark Flavor Asymmetry of Proton
• Extracting the transversity distributions from single-hadron and dihadron production
• Taming the Pion Cloud of the Nucleon
• Strange quark asymmetry in the proton in chiral effective theory
• Non-perturbative structure of the polarized nucleon sea
• Probing the Sea Quark Content of the Proton with One-Particle-Inclusive Processes
• Leading proton spectrum from DIS at HERA
• Evolution Equations for Connected and Disconnected Sea Parton Distributions
• Phenomenology of the Flavor-Asymmetry in the Light-Quark Sea of the Nucleon
• Constraints on $s-\bar{s}$ asymmetry of the proton in chiral effective theory
• Do we expect light flavor sea-quark asymmetry also for the spin-dependent distribution functions of the nucleon?
• Nuclear effects in the proton-deuteron Drell-Yan process
• On the extraction of the intrinsic light-quark sea in the proton
• Current fragmentation in semiinclusive leptoproduction
• Gauge invariance and kaon production in deep inelastic scattering at low scales
• Sea Quark Flavor Asymmetry of Hadrons in Statistical Balance Model
• Pion-Exchange and Fermi-Motion Effects on the Proton-Deuteron Drell-Yan Process
• The Structure of the Pion and Nucleon, and Leading Neutron Production at HERA

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• Polarized Antimatter in the Proton from Global QCD Analysis
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• What does kinematical target mass sensitivity in DIS reveal about hadron structure?
• Light-front wave functions of mesons, baryons and pentaquarks, with topology-induced local 4-quark interaction
• Measurement of flavor asymmetry of light-quark sea in the proton with Drell-Yan dimuon production in $p+p$ and $p+d$ collisions at 120 GeV
• Strangeness content of the pion in the U(3) Nambu-Jona-Lasinio model
• Extraction of the neutron F2 structure function from inclusive proton and deuteron deep-inelastic scattering data
• Pions in Proton Structure and Everywhere Else
• Flavor asymmetry from the non-perturbative nucleon sea
• Effect of symmetry breaking of polarized light sea quarks on the nucleon and nuclear structure functions, and sum rules
• Regarding the distribution of glue in the pion
• Bayesian Monte Carlo extraction of sea asymmetry with SeaQuest and STAR data
• Non-perturbative flavor asymmetry in the nucleon and deuteron: The light-front Hamiltonian effective field theory approach