Kevin Sprague | Searcharxiv

arXiv1999

Vacuum Condensates and the Anomalous Magnetic Moment of a Dirac Fermion

We address anticipated fermion-antifermion and dimension-4 gauge-field vacuum-condensate contributions to the magnetic portion of the fermion-photon vertex function in the presence of a vacuum with nonperturbative content, such as that of QCD. We discuss how inclusion of such condensate contributions may lead to a vanishing anomalous magnetic moment, in which case vacuum condensates may account for the apparent consistency between constituent quark masses characterizing baryon magnetic moments and those characterizing baryon spectroscopy.

hep-ph↗

arXiv1998

Fermion-Antifermion Condensate Contribution to the Anomalous Magnetic Moment of a Fundamental Dirac Fermion

We consider the contribution of fermion-antifermion condensates to the anomalous magnetic moment of a fermion in a vacuum in which such condensates exist. The real part of the condensate contribution to the anomalous magnetic moment is shown to be zero. A nonzero imaginary part is obtained below the kinematic threshold for intermediate fermion-antifermion pairs. The calculation is shown to be gauge-parameter independent provided a single fermion mass characterizes both the fermion propagator and condensate-sensitive contributions, suggestive of a dynamically-generated fermion mass. The nonzero imaginary part is then argued to correspond to the kinematic production of the intermediate-state Goldstone bosons anticipated from a chiral-noninvariant vacuum. Finally, speculations are presented concerning the applicability of these results to quark electromagnetic properties.

hep-ph↗