Isospin violating corrections to nucleon electroweak form factors

Journal Article · Sun Oct 01 04:00:00 EDT 1995 · Bulletin of the American Physical Society

OSTI ID:255459

Pollock, S; Dmitrasinovic, V ^[1]

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1. Univ. of Colorado, Boulder, CO (United States)

We examine isospin breaking in the nucleon wave functions due to the {mu} - d quark mass difference and the Coulomb interaction among the quarks, and their consequences on the nucleon electroweak form factors in a nonrelativistic constituent quark model. The mechanically induced isospin breaking in the nucleon wave functions and electroweak form factors are exactly evaluated in this model. We calculate the electromagnetically induced isospin admixtures by using first-order perturbation theory, including the lowest-lying resonance with nucleon quantum numbers but isospin 3/2. We find a small (< 1%), but finite correction to the anomalous magnetic moments of the nucleon stemming almost entirely from the quark mass difference, while the static nucleon axial coupling remains uncorrected. Corrections of the same order of magnitude appear in charge, magnetic, and axial radii of the nucleon. The correction to the charge radius in this model is primarily isoacalar, and may be of some significance for the extraction of the strangeness radius from e.g. elastic forward angle parity violating electron-proton asymmetries, or elastic {sup 4}He(e, e{sup {prime}}) experiments.

• OSTI ID: 255459
• Report Number(s): CONF-9510116--
• Journal Information: Bulletin of the American Physical Society, Journal Name: Bulletin of the American Physical Society Journal Issue: 10 Vol. 40; ISSN BAPSA6; ISSN 0003-0503
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
FORM FACTORS
ISOSPIN
MAGNETIC MOMENTS
NUCLEONS
QUARK MODEL
SYMMETRY BREAKING