Abstract
The photoproduction reaction of $\gamma p \to \eta^\prime p$ is investigated based on an effective Lagrangian approach in the tree-level approximation, with the purpose being to understand the reaction mechanisms and to extract the resonance contents and the associated resonance parameters in this reaction. Apart from the $t$-channel $\rho$ and $\omega$ exchanges, $s$- and $u$-channel nucleon exchanges, and generalized contact term, the exchanges of a minimum number of nucleon resonances in the $s$ channel are taken into account in constructing the reaction amplitudes to describe the experimental data. It is found that a satisfactory description of the available data on both differential cross sections and photon beam asymmetries can be obtained by including in the $s$ channel the exchanges of the $N(1875)3/2^-$ and $N(2040)3/2^+$ resonances. The reaction mechanisms of $\gamma p \to \eta^\prime p$ are discussed and a prediction for the target nucleon asymmetries is presented.
Highlights
The study of nucleon resonances (NÃs) has been of great interest in hadron physics, since a deeper understanding of NÃs can help us get insight into the nonperturbative regime of quantum chromodynamics
III, we present our theoretical results of the differential cross sections and the photon beam asymmetries, where discussions about the reaction mechanisms are made and a prediction of the target asymmetries for γp → η0p is given
After the availability of the photon beam asymmetry data, simultaneous descriptions of the differential cross section data and the photon beam asymmetry data for γp → η0p have only been performed by the BnGa group [10,11] and in the updated ηMAID model [12]
Summary
The study of nucleon resonances (NÃs) has been of great interest in hadron physics, since a deeper understanding of NÃs can help us get insight into the nonperturbative regime of quantum chromodynamics. The photon beam asymmetry data from the GRALL and the CLAS Collaborations together with the differential cross section data for γp → η0p have been simultaneously described in partial-wave analysis performed by the BnGa group [10,11] and in the updated ηMAID model [12]. In addition to the t-channel ρ and ω exchanges, s- and u-channel nucleon (N) exchanges, and generalized contact current, we consider as few as possible N resonances in the s channel in constructing the reaction amplitudes to describe the available differential cross section data and photon beam asymmetry data from the CLAS, A2, and GRALL Collaborations [1,3,4,5].
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