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.

中文翻译：

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在光核上中性伪标量介子$$ \ boldsymbol {\ pi ^ {0} \ pi ^ {0}} $$和$$ \ boldsymbol {\ pi ^ {0} \ eta} $$在光核上的相干光产生

摘要

\（\ pi ^ {0} \ pi ^ {0} \）和\（\ pi ^ {0} \ eta \）在\（A \ leqslant 7 \）的质量数区域上的相干光产生在阈值和\（E _ {\ gamma} = 2 \） GeV的实验室光子能量之间的范围内，系统地研究了Sn。原子核上光产生的幅度是基于脉冲近似法构造的，并考虑了介子-原子核最终态相互作用的许多过程。pion散射过程\（\ pi N \ to \ pi N \）和\（\ pi N \ to \ eta N \）发生在旁观者核子上（\（\ pi ^ {+/-} \ pi ^ {0 } \ pi ^ {0} \）和\（\ pi ^ {+/-} \ pi ^ {0} \ eta \）生产观众核子对\（\ pi ^ {+/-} \）的吸收，以及三体\（\ pi \） – NN和\（\ eta \） – NN相互作用是首次在统一的微观方法中进行描述。