Effects of nucleon resonances on $\eta$ photoproduction off the neutron reexamined

Suh, Jung-Min (Department of Physics, Inha University, Incheon 22212, Republic of Korea) ; Kim, Sang-Ho (Center for Extreme Nuclear Matters (CENuM), Korea University, Seoul 02841, Republic of Korea) (Department of Physics, Pukyong National University (PKNU), Busan 48513, Republic of Korea) ; Kim, Hyun-Chul (Department of Physics, Inha University, Incheon 22212, Republic of Korea) (Advanced Science Research Center, Japan Atomic Energy Agency, Shirakata, Tokai, Ibaraki 319-1195, Japan) (School of Physics, Korea Institute for Advanced Study (KIAS), Seoul 02455, Republic of Korea)

12 April 2019

Abstract: We investigate $\eta$ photoproduction off the neutron target, i.e., $\gamma n\to \eta n$, employing an effective Lagrangian method combining with a Regge approach. As a background, we consider nucleon exchange in the $s$-channel diagram and $\rho$- and $\omega$-meson Regge trajectories in the $t$ channel. The role of nucleon resonances given in the Review of Particle Data Group in the range of $W\approx 1500–2100\text{}\text{}\mathrm{MeV}$ and the narrow nucleon resonance $N\left(1685,1/{2}^{+}\right)$ is extensively studied. The numerical results of the total and differential cross sections, double polarization observable $E$, helicity-dependent cross sections ${\sigma }_{1/2}$, ${\sigma }_{3/2}$, and the Legendre coefficients of the angular distributions for ${\sigma }_{1/2}$, ${\sigma }_{3/2}$ are found to be in qualitative agreement with the recent A2 experimental data. The predictions of the beam asymmetry are also given.

Published in: Physical Review D 99 (2019)