Electromagnetic Properties of Baryons and the Quark Model

概要

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The electromagnetic properties of baryons are investigated from the viewpoint of the Sakata Model, in which quarks are chosen as the three fundamental particles. Since vector mesons couple to the baryon indirectly through the constituent quarks, the electromagnetic form factor of the baryon has a further contribution coming from the baryon wave function as well as contributions from ρ, ω and φ. This allows us to get rid of the difficulty encountered in the usual vector meson model in fitting the data with only the known ρ, ω and φ. It is also shown that in the "nonet limit" only ρ and ω contribute to the nucleon form factors. This explains the experimental relations G_p^E≃G_p^M/μ_p≈G_n^M/μ_n and G_n^E≃0. The form factors of the other baryons are also derived. Furthermore, knowledge of the form factors is applied to estimate the electromagnetic mass differences between baryons. According to this analysis it is predicted that the nucleon form factors will continue to maintain a value appreciably different from zero up to a fairly large value of k^2. Sum rules and inequalities among the mass differences are derived in our model with SU(3) breaking effects included.
理論物理学刊行会の論文
1966-12-25