Photoproduction ofN*Resonances in the Quark Model

η′photoproduction on the nucleon in the quark model

“…There exists large disagreement between model fits and the experimental observations. As mentioned earlier, in γn → η ′ n states of [70, 4 8] representation can contribute here while they are forbidden in γp → η ′ p by the Moorhouse selection rule [29]. Therefore, we expect that more information about the s-channel resonances can be gained in the study of γn → η ′ n. For instance, as the only D 15 state in the first orbital excitations and belonging to [70, 4 8], D 15 (1675) can only be excited by γn instead of γp.…”

“…Similar to the η production, an interesting difference between γp → η ′ p and γn → η ′ n is that in the γp reactions, contributions from states of representation [70, 4 8] will be forbidden by the Moorhouse selection rule [29] in the SU(6)⊗O(3) symmetry. As a consequence, only states of [56, 2 8] and [70, 2 8] would contribute to γp → η ′ p. In contrast, all the octet states can contribute to the γn reactions.…”

Nucleonic resonance excitations with linearly polarized photons inγp→ωp

“…In γp → ωp, the isospin conservation eliminates contributions from intermediate states with isospin 3/2. In addition, the Moorhouse selection rules [26] eliminate those nucleonic states of representation [70, 4 8, n, L, J] in the NRCQM from contributing. Therefore, only 8 intermediate nucleonic resonances contribute for n ≤ 2 in the harmonic oscillator basis, i.e.…”

Quark model approach to the $\eta$ meson electroproduction on the proton

“…At quark level, the transition matrix element M f i can be expressed as the sum over the t-, s-and u-channel transitions, i.e. to the proton target reaction [18]. Thus, eight isospin-1/2 resonances corresponding to the harmonic oscillator quantum numbers n=1 and 2, and the nucleon pole terms, are to be included explicitly.…”