Magnetic dipole moment of the S11(1535) from the γp→γηp reaction

Abstract

The γp → γηp reaction in the S 11 (1535) resonance region is investigated as a method to access the S 11 (1535) magnetic dipole moment. To study the feasibility, we perform calculations of the γp → γηp process within an effective Lagrangian approach containing both the S 11 resonant mechanism and a background of non-resonant contributions. Predictions are made for the forthcoming experiments. In particular, we focus on the sensitivity of cross sections and photon asymmetries to the S 11 (1535) magnetic dipole moment.

Unitary model for theγp→γπ0preaction and the magnetic dipole moment of theΔ+

“…This low-energy theorem was derived in Ref. [44] for radiative photoproduction of a neutral meson. In Appendix A, we first apply this theorem to the γp → γπ 0 p reaction and then extend it to the γp → γπ + n process.…”

Magnetic moments of the low-lying JP = 1/2-, 3/2- $\Lambda$ resonances within the framework of the chiral quark model

“…The orbital angular momenta l ρ and l λ operate over these spatial wave function as follows [4] (in the following we omit the index N in the wave functions for simplicity)…”

“…There are different ways to look into the underlying structure of a hadron and a lot of effort has been spent in this direction, specially, by studying radiative decays and electromagnetic properties of the ground state baryons and mesons and their resonances [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. These studies reveal that instead of the traditional picture of a baryon as a three quark state and a meson as a quark antiquark pair [15], some excited hadrons seem to have more complicated structures, where the contribution from the meson cloud or a picture in which the hadrons are the building blocks of the theory seem to take an advantage.…”

Magnetic moments of negative parity baryons from the effective Hamiltonian approach to QCD

“…Experimentally, magnetic moments of these states can be extracted through bremsstrahlung processes in photoand electro-production of mesons at intermediate energies. For N(1535) a similar process γp → γηp can be used [9], but to date no such measurements have been made.…”

“…based on constituent quark model [9], unitarized chiral perturbation theory (UχPT) [10], chiral constituent quark model (χCQM ) [11], Bethe-Salpeter approach (BSA) [12] and on the lattice [13]. Comparison study of magnetic moments for positive-and negative-parity states offers insight into underlying quark-gluon dynamics.…”