Analysis of baryon magnetic moments in large-N[sub c] chiral perturbation theory

Abstract

The baryon magnetic and transition magnetic moments are computed in heavy baryon chiral perturbation theory in the large-Nc limit, where Nc is the number of colors. One-loop nonanalytic corrections of orders m 1/2 q and mq ln mq are incorporated into the analysis, where contributions of both intermediate octet and decuplet baryon states are explicitly included. Expressions are obtained in the limit of vanishing baryon mass differences and compared with the current experimental data. Furthermore, a comparison with conventional heavy baryon chiral perturbation theory is carried out for three light quarks flavors and at the physical value Nc = 3.1/2 q and m q ln m q . Caldi and Pagels [16] focused on calculating what were supposed to be the leading corrections, namely, those of order m 1/2 s , and concluded that, in general, the corrections turned out to be at least as large as the zeroth-order contribution so that the perturbation expansion would break down. In turn, Gasser et. al. [17] reanalyzed

Electromagnetic and gravitational form factors of $Δ$ resonance in a covariant quark-diquark approach

“…, where e is the electric charge [66]. We can compare the obtained magneticdipole, electric-quadrupole and magnetic-octupole moments to the results of different model calculations, such as non-relativistic quark model (NQM) [67][68][69], relativistic quark model (RQM) [70], QCD sum rules (QCDSR) [71][72][73][74], light cone QCD sum rules (LCQSR) [75], Large N c [76][77][78], chiral quark model with meson exchange currents (χQMEC) [79,80], QCD quark model (QCDQM) [81,82], chiral bag model (CBM) [83], general parameterization QCD (GPQCD) [84], chiral quark-soliton model (χQSM) [85], effective mass and screened charge scheme (EMS) [86,87], chiral perturbation theory (χPT) [88][89][90], lattice QCD (LQCD) [91][92][93], and chiral constituent quark model (χCQM) [94]. Tables 2, 3, and 4 list the comparisons of our magnetic, quadrupole, and octupole moments with other model calculations, respectively.…”