pi. NN form factor for explaining sea-quark distributions in the nucleon

Journal Article · Tue Jan 01 00:00:00 EST 1991 · Physical Review, D (Particles Fields); (USA)

DOI:https://doi.org/10.1103/PhysRevD.43.59· OSTI ID:6143119

Kumano, S ^[1]

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1. Nuclear Theory Center, Indiana University, 2401 Milo B. Sampson Lane, Bloomington, Indiana 47408-0768 (US)

We reinvestigate a soft {pi}{ital NN} form factor with a monopole cutoff parameter {Lambda}{sub 1}{lt}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 {Lambda}{sub 1}{lt}0.65--0.7 GeV estimated in this investigation. Studying processes involving {pi}{ital NN} and {pi}{ital N}{Delta} vertices, we find that the limit for the dipole form factor is {Lambda}{sub 2}{lt}0.95 GeV (which corresponds to {Lambda}{sub 1}{lt}0.6 GeV). Therefore, a typical {pi}{ital NN} form factor with {Lambda}{sub 1}{similar to}0.6 GeV in quark models could be consistent with deep-inelastic experimental data at this stage. However, it is softer than a {pi}{ital NN} form factor with {Lambda}{sub 1}{similar to}1 GeV widely used in nuclear physics. Using the cutoff {Lambda}{sub 2}=0.95 GeV, we investigate pionic contributions to a SU(2){sub {ital f}}-breaking distribution {ital {bar u}}({ital x}){minus}{ital {bar d}}({ital x}) in the nucleon. We find that the pionic contributions to {ital {bar u}}({ital x}){minus}{ital {bar d}}({ital x}) are negative and a contribution to the deviation from the Gottfried sum rule is estimated to be {minus}0.041, which could explain a part of the discrepancies indicated by recent New Muon Collaboration experiments.

• OSTI ID: 6143119
• Journal Information: Physical Review, D (Particles Fields); (USA), Vol. 43:1; ISSN 0556-2821
• Country of Publication: United States
• Language: English

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72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
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FORM FACTORS
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STRUCTURE FUNCTIONS
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