First measurement of coherent phi-meson photoproduction from 4He near threshold
First measurement of coherent phi-meson photoproduction from 4He near threshold
复制标题
首次测量 4He 近阈值的相干 phi-介子光产生
DOI：
10.1103/physrevc.97.035208
复制
发表时间：
2018
影响因子：
3.1
通讯作者：
T. Hiraiwa et al. (LEPS collaboration)
中科院分区：
文献类型：
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作者：
T. Hiraiwa et al. (LEPS collaboration)
首次测量了线偏振光子入射氦-4的相干介子光产生的前角微分截面和衰减角分布。多亏了带有自旋奇偶的目标，不存在非自然奇偶交换，因此可以清楚地研究自然奇偶交换。相对于光子偏振的衰变不对称性非常接近最大值。这确保了自然平价交换在这一反应中的强大优势(%)。为了评估自然宇称交换对阈值附近反应的前向截面()的贡献，分析了反应的前向截面()的能量依赖性。与数据的比较表明，在临界值附近，由于自然奇偶交换和/或自然奇偶交换和非自然奇偶交换之间的破坏性干扰而引起的正向截面的增强是必要的。
The differential cross sections and decay angular distributions for coherent-meson photoproduction from helium-4 are measured for the first time at forward angles with linearly polarized photons in the energy range. Thanks to the target with spin-parity, unnatural-parity exchanges are absent, and thus natural-parity exchanges can be investigated clearly. The decay asymmetry with respect to photon polarization is shown to be very close to the maximal value. This ensures the strong dominance (%) of natural-parity exchanges in this reaction. To evaluate the contribution from natural-parity exchanges to the forward cross section () for thereaction near threshold, the energy dependence of the forward cross section () for thereaction is analyzed. The comparison todata suggests that enhancement of the forward cross section arising from natural-parity exchanges and/or destructive interference between natural-parity and unnatural-parity exchanges is needed in thereaction near threshold.