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

Abstract

Evidence for a flavor asymmetry between the $\bar{u}$ and $\bar{d}$ quark distributions in the proton has been found in deep-inelastic scattering and Drell-Yan experiments. The pronounced dependence of this flavor asymmetry on $x$ (fraction of nucleon momentum carried by partons) observed in the Fermilab E866 Drell-Yan experiment suggested a drop of the $\bar{d}\left(x\right)/\bar{u}\left(x\right)$ ratio in the $x>0.15$ region. We report results from the SeaQuest Fermilab E906 experiment with improved statistical precision for $\bar{d}\left(x\right)/\bar{u}\left(x\right)$ in the large $x$ region up to $x=0.45$ using the 120 GeV proton beam. Two different methods for extracting the Drell-Yan cross section ratios, ${\sigma }^{pd}/2{\sigma }^{pp}$, from the SeaQuest data give consistent results. The $\bar{d}\left(x\right)/\bar{u}\left(x\right)$ ratios and the $\bar{d}\left(x\right)-\bar{u}\left(x\right)$ differences are deduced from these cross section ratios for $0.13<x<0.45$. The SeaQuest and E866/NuSea $\bar{d}\left(x\right)/\bar{u}\left(x\right)$ ratios are in good agreement for the $x\lesssim 0.25$ region. The new SeaQuest data, however, show that $\bar{d}\left(x\right)$ continues to be greater than $\bar{u}\left(x\right)$ up to the highest $x$ value ($x=0.45$). The new results on $\bar{d}\left(x\right)/\bar{u}\left(x\right)$ and $\bar{d}\left(x\right)-\bar{u}\left(x\right)$ are compared with various parton distribution functions and theoretical calculations.

References in corpus (37)

• New parton distribution functions from a global analysis of quantum chromodynamics
• Instantons in QCD
• An NNLO subtraction formalism in hadron collisions and its application to Higgs boson production at the LHC
• Vector boson production at hadron colliders: a fully exclusive QCD calculation at NNLO
• Parton Physics on Euclidean Lattice
• New CTEQ global analysis of quantum chromodynamics with high-precision data from the LHC
• The Path to Proton Structure at One-Percent Accuracy
• Improved Measurement of the $\bar{d}/\bar{u}$ Asymmetry in the Nucleon Sea
• Measurement of the Light Antiquark Flavor Asymmetry in the Nucleon Sea
• Flavor Asymmetry of Antiquark Distributions in the Nucleon
• Nucleon Parton Distributions at Low Normalization Point in the Large N_c Limit
• Flavor Structure of the Nucleon Sea from Lattice QCD
• The Flavor Asymmetry of the Light Quark Sea from Semi-inclusive Deep-inelastic Scattering
• Flavor Asymmetry of Light Quarks in the Nucleon Sea
• dbar/ubar Asymmetry and the Origin of the Nucleon Sea
• A statistical approach for polarized parton distributions
• Flavor and Spin Contents of the Nucleon in the Quark Model with Chiral Symmetry
• The Asymmetry of Antimatter in the Proton
• Dynamics of Light Antiquarks in the Proton
• On the Flavor Structure of the Constituent Quark
• The statistical parton distributions: status and prospects
• Flavor Asymmetry of the Nucleon Sea and the Five-Quark Components of the Nucleons
• Flavor Structure of the Nucleon Sea
• Charge Symmetry at the Partonic Level
• Light-flavor sea-quark distributions in the nucleon in the SU(3) chiral quark soliton model (I) -- phenomenological predictions --
• Flavor decomposition of the nucleon unpolarized, helicity and transversity parton distribution functions from lattice QCD simulations
• Interpreting the Neutron's Electric Form Factor: Rest Frame Charge Distribution or Foldy Term?
• Parton distributions of light quarks and antiquarks in the proton
• The Sea of Quarks and Antiquarks in the Nucleon: a Review
• Measurements of $W$ and $Z/{\gamma }^{\ast }$ cross sections and their ratios in $p+p$ collisions at RHIC
• The Drell-Yan process as a testing ground for parton distributions up to LHC
• Chiral Light Front Perturbation Theory and the Flavor Dependence of the Light-Quark Nucleon Sea
• Nuclear effects in the proton-deuteron Drell-Yan process
• Pion-Exchange and Fermi-Motion Effects on the Proton-Deuteron Drell-Yan Process
• Pions in Proton Structure and Everywhere Else
• FPGA-based trigger system for the Fermilab SeaQuest experiment
• Bayesian Monte Carlo extraction of sea asymmetry with SeaQuest and STAR data

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• Reflections on Chiral Symmetry within QCD
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• Non-perturbative flavor asymmetry in the nucleon and deuteron: The light-front Hamiltonian effective field theory approach
• QCD analysis of valence structure functions using deep inelastic lepton-nucleon scattering