SU(2)-Flavor-Symmetry Breaking in Nuclear Antiquark Distributions

Abstract

SU(2)-flavor-symmetry breaking in antiquark distributions of the nucleon was suggested by the New Muon Collaboration (NMC) in deep inelastic muon scattering. As an independent test, Drell-Yan data for the tungsten target have been used for examining the asymmetry. We investigate whether there exists significant modification of the $\bar{u}-\bar{d}$ distribution in nuclei in a parton recombination model. It should be noted that a finite $\bar{u}-\bar{d}$ distribution is theoretically possible in nuclei even if the sea is $SU(2{)}_f$ symmetric in the nucleon. In neutron-excess nuclei such as the tungsten, there exist more $d$-valence quarks than $u$-valence quarks, so that more $\bar{d}$-quarks are lost than $\bar{u}$-quarks are due to parton recombinations in the small $x$ region. Our results suggest that the nuclear modification in the tungsten is a 2--10 % effect on the $\bar{u}-\bar{d}$ distribution suggested by the NMC data. Nuclear effects on the flavor asymmetric distribution could be an interesting topic for future theoretical and experimental investigations.

LATEX 10 pages (Figs. 1-3 are available upon request), SAGA-HE-67-94

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Cited by in corpus (9)

• Flavor Asymmetry of Antiquark Distributions in the Nucleon
• Determination of nuclear parton distributions
• Flavor Asymmetry of Light Quarks in the Nucleon Sea
• Numerical solution of $Q^2$ evolution equations in a brute-force method
• Towards a Unified Model of Neutrino-Nucleus Reactions for Neutrino Oscillation Experiments
• Nuclear Shadowing in the Structure Function $F_3(x)$
• Deep inelastic scattering on asymmetric nuclei
• Pions in isospin asymmetric matter and nuclear Drell-Yan scattering
• Parametrization of nuclear parton distributions