Magnetic moments of the low-lying $$\tfrac{1} {2}^ -$$ octet baryon resonances

Abstract

The magnetic moments of the negative parity octet resonances with spin 1 2 : N * (1535), N * (1650), Σ * (1620), and Ξ * (1690) have been calculated within the framework of the chiral constituent quark model. In this approach, the presence of the polarized qq pairs (or the meson cloud, in other words) is considered by using the Lagrangian for Goldstone boson emission from the constituent quarks. Further, the explicit contributions coming from the spin and orbital angular momentum, including the effects of the configurations mixing between the states with different spins, are obtained. The motivation for these calculations comes from the recent interest in experimental measurement of the magnetic moment of the S 11 (1535) resonance and of similar calculations being done within lattice quantum chromodynamics approaches. Our results can be compared with those expected to come from these sources.

Magnetic moments ofJP=32−baryons in QCD

“…The very first effort in measuring the magnetic moment of the Δ þ ð1232Þ in the reaction γp → pπ 0 γ has been realized at MAMI, and a future program to get information about the magnetic moment of the N Ã ð1535Þ baryon in the reaction γp → pηγ has already been planned. The magnetic moments of the spin-1=2 negative parity baryons have been calculated within the nonrelativistic quark model [6], simple quark model [7], lattice QCD [8], chiral perturbation theory [9], light cone QCD sum rules (LCSR) [10], and effective Hamiltonian model [11].…”

Elastic Form Factors of Nucleon Excitations

“…We consider two constituent quark model (QM) predictions of the magnetic moments from Refs. [6,13], and two chiral constituent quark model (χQM) calculations which take the quark model calculations and include effects from the pion cloud [13,14].…”

QCD sum rules for 70 - plet baryons

“…In the quark model these baryons are assigned usually to the 70-plet representation of SU (6), in contrast to the 1/2 + baryons of the 56-plet (see [1,2] and the references therein).…”