Coherent Photoproduction of Neutral Pseudoscalar Mesons $\boldsymbol{\pi^{0}\pi^{0}}$ and $\boldsymbol{\pi^{0}\eta}$ on Light Nuclei

Abstract

The coherent photoproduction of $\pi^{0}\pi^{0}$ and $\pi^{0}\eta$ on nuclei in the mass-number region of $A\leqslant 7$ is studied systematically over the range between the threshold and the laboratory photon energy of $E_{\gamma}=2$ GeV. The amplitude for photoproduction on nuclei is constructed on the basis of the impulse approximation with allowance for a number of processes responsible for meson–nucleus final-state interaction. The pion-rescattering processes $\pi N\to\pi N$ and $\pi N\to\eta N$ occurring on spectator nucleons, $\pi^{+/-}\pi^{0}\pi^{0}$ and $\pi^{+/-}\pi^{0}\eta$ production followed by $\pi^{+/-}$ absorption by spectator nucleons, and three-body $\pi$–NN and $\eta$–NN interactions are described for the first time within a unified microscopic approach.