πNNform factor for explaining sea-quark distributions in the nucleon
- 1 January 1991
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review D
- Vol. 43 (1), 59-63
- https://doi.org/10.1103/physrevd.43.59
Abstract
We reinvestigate a soft πNN form factor with a monopole cutoff parameter <0.5 GeV obtained by Frankfurt, Mankiewicz, and Strikman for explaining sea-quark distributions in the nucleon. It is found that their estimate is small in comparison to the limit <0.65–0.7 GeV estimated in this investigation. Studying processes involving πNN and πNΔ vertices, we find that the limit for the dipole form factor is <0.95 GeV (which corresponds to <0.6 GeV). Therefore, a typical πNN form factor with ∼0.6 GeV in quark models could be consistent with deep-inelastic experimental data at this stage. However, it is softer than a πNN form factor with ∼1 GeV widely used in nuclear physics. Using the cutoff =0.95 GeV, we investigate pionic contributions to a SU(2-breaking distribution u¯(x)-d¯(x) in the nucleon. We find that the pionic contributions to u¯(x)-d¯(x) are negative and a contribution to the deviation from the Gottfried sum rule is estimated to be -0.041, which could explain a part of the discrepancies indicated by recent New Muon Collaboration experiments.
Keywords
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