Effects of. pi. NN form factor on pionic contributions to u ( x ) minus d ( x ) distribution in the nucleon

Journal Article · Wed May 01 04:00:00 EDT 1991 · Physical Review, D (Particles Fields); (USA)

DOI:https://doi.org/10.1103/PhysRevD.43.3067· OSTI ID:5677799

Kumano, S ^[1]

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

Effects of the cutoff parameter in {pi}{ital NN} and {pi}{ital N}{Delta} vertices on pionic contributions to {ital {bar u}}({ital x}){minus}{ital {bar d}}({ital x}) in the nucleon and the Gottfried sum rule are investigated. A typical pionic contribution to the deviation from the Gottfried sum rule is found around {minus}0.04 (about 50% of the discrepancy found by the New Muon Collaboration) for the dipole cutoff parameter {Lambda}{sub 2}{similar to}1 GeV. This negative contribution is due to an excess of {ital {bar d}} over {ital {bar u}} in {pi}{sup +} and it is (partly) canceled by a positive contribution due to an excess of {ital {bar u}} over {ital {bar d}} in an extra {pi}{sup {minus}} in the {pi}{ital N}{Delta} process. We find that the cancellation is significant especially for the large cutoff ({Lambda}{sub 2}=1.2--2.0 GeV); thus, the distribution {ital {bar u}}{minus}{ital {bar d}} is less sensitive to the cutoff parameter than an SU(3){sub {ital f}}-breaking distribution ({ital {bar u}}+{ital {bar d}})/2{minus}{ital {bar s}}. For the same reason, it is very important to include the {pi}{ital N}{Delta} process in addition to the {pi}{ital NN} process. Pionic contributions to {ital {bar u}}({ital x}){minus}{ital u}({ital x}), {ital d}({ital x}){minus}{ital {bar d}}({ital x}), and {ital d}({ital x}){minus}{ital u}({ital x}) distributions in the nucleon are also discussed. Because pionic contributions produce an asymmetric sea, ({ital u}{sub {ital s}}{ne}{ital {bar u}}{sub {ital s}}){sub pionic} and ({ital d}{sub {ital s}}{ne}{ital {bar d}}{sub {ital s}}){sub pionic}, we must be careful in discussing valence- and sea-quark distributions in the nucleon.

• DOE Contract Number: FG02-87ER40365
• OSTI ID: 5677799
• Journal Information: Physical Review, D (Particles Fields); (USA), Journal Name: Physical Review, D (Particles Fields); (USA) Vol. 43:9; ISSN PRVDA; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

645204* -- High Energy Physics-- Particle Interactions & Properties-Theoretical-- Strong Interactions & Properties
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ANTIMATTER
ANTIPARTICLES
BARYONS
COUPLING CONSTANTS
ELEMENTARY PARTICLES
EQUATIONS
FERMIONS
FORM FACTORS
FUNCTIONS
HADRON-HADRON INTERACTIONS
HADRONS
INTERACTIONS
LIE GROUPS
MESON-BARYON INTERACTIONS
MESON-NUCLEON INTERACTIONS
NUCLEONS
PARTICLE INTERACTIONS
PARTICLE PROPERTIES
PION-NUCLEON INTERACTIONS
POSTULATED PARTICLES
PROBABILITY
QUARKS
STRUCTURE FUNCTIONS
SU GROUPS
SU-2 GROUPS
SU-3 GROUPS
SUM RULES
SYMMETRY BREAKING
SYMMETRY GROUPS
VALENCE