Electroweak structure of the nucleon, meson cloud, and light-cone wave functions

Journal Article · Mon Oct 01 04:00:00 EDT 2007 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.76.074011· OSTI ID:21032338

Pasquini, B; Boffi, S ^[1]

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1. Dipartimento di Fisica Nucleare e Teorica, Universita degli Studi di Pavia and INFN, Sezione di Pavia, Pavia (Italy)

The meson-cloud model of the nucleon consisting of a system of three valence quarks surrounded by a meson cloud is applied to study the electroweak structure of the proton and neutron. Light-cone wave functions are derived for the dressed nucleon as pictured to be part of the time a bare nucleon and part of the time a baryon-meson system. Configurations are considered where the baryon can be a nucleon or a {delta} and the meson can be a pion as well as a vector meson such as the {rho} or the {omega}. An overall good description of the electroweak form factors is obtained. The contribution of the meson cloud is small and only significant at low Q{sup 2}. Mixed-symmetry S{sup '}-wave components in the wave function are most important to reproduce the neutron electric form factor. Charge and magnetization densities are deduced as a function of both the radial distance from the nucleon center and the transverse distance with respect to the direction of the three-momentum transfer. In the latter case, a central negative charge is found for the neutron. The up and down quark distributions associated with the Fourier transform of the axial form factor have opposite sign, with the consequence that the probability to find an up (down) quark with positive helicity is maximal when it is (anti)aligned with the proton helicity.

• OSTI ID: 21032338
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 7 Vol. 76; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
D QUARKS
DISTRIBUTION
FORM FACTORS
FOUR MOMENTUM TRANSFER
FOURIER TRANSFORMATION
HELICITY
LIGHT CONE
MAGNETIZATION
NEUTRONS
OMEGA-782 MESONS
PARTICLE STRUCTURE
PIONS
PROBABILITY
PROTONS
RHO-770 MESONS
STANDARD MODEL
SYMMETRY
VALENCE
WAVE FUNCTIONS