Recoil effects in a bag model

Abstract

In this paper, we invoke the formalism used previously by Krajcik and Foldy to obtain the relativistic center-of-mass coordinates for a system of pointlike Dirac particles. This procedure allows us to investigate a recent dispute regarding the size, as well as the proper formulation, of recoil corrections to baryon magnetic moments in a bag model. Our results suggest that the overall center-of-mass-system motion, when factored out properly to yield the momentum-conservation δ functions, does not result in the additional and sizable recoil corrections as addressed specifically by Betz and Goldflam as well as by Guichon. It appears that the major recoil contribution to the baryon magnetic moment comes from the spinor rotation of the constituent quarks. Although the dispute in question is related to effects of first order in q/M with q the magnitude of the momentum transfer and M the baryon mass and so can be settled with confidence, it appears that terms of order (q/M${)}^2$ or beyond are highly model-dependent.