Differential cross section and photon-beam asymmetry for the gamma p -> pi- Delta++(1232) reaction at forward pi- angles for Egamma=1.5-2.95 GeV
Differential cross section and photon-beam asymmetry for the gamma p -> pi- Delta++(1232) reaction at forward pi- angles for Egamma=1.5-2.95 GeV
复制标题
Egamma=1.5-2.95 GeV 的正向 pi 角处的 gamma p -> pi- Delta (1232) 反应的微分横截面和光子束不对称性
DOI：
10.1103/physrevlett.120.202004
复制
发表时间：
2018
影响因子：
8.6
通讯作者：
H. Kohri et al. (LEPS collaboration)
中科院分区：
文献类型：
--
作者：
児玉康一;神谷剛宏，市村雅一，中村光廣;H. Kohri et al. (LEPS collaboration)
已在 SPring-8/LEPS 上测量了反应的差异横截面和光子束不对称性。在该运动学区域首次获得了高统计截面数据，并且首次获得了不对称数据。该反应对于研究质子最终状态的纯夸克对的产生机制具有独特的功能。尽管横截面中没有明显的峰结构，但观察到超过理论预测的不可忽略的过量。在目前的大多数运动学区域中发现不对称性为负，表明交换在通道中占主导地位。正向介子产生角的负不对称性不同于先前测量的在最终状态下产生a或安夸克对的光产生反应的不对称性。需要引入核子共振和额外的非自然宇称交换的先进理论模型来重现当前数据。
Differential cross sections and photon-beam asymmetries for thereaction have been measured forandat SPring-8/LEPS. The first-ever high statistics cross-section data are obtained in this kinematical region, and the asymmetry data forare obtained for the first time. This reaction has a unique feature for studying the production mechanisms of a purequark pair in the final state from the proton. Although there is no distinct peak structure in the cross sections, a non-negligible excess over the theoretical predictions is observed at. The asymmetries are found to be negative in most of the present kinematical regions, suggesting the dominance ofexchange in thechannel. The negative asymmetries at forward meson production angles are different from the asymmetries previously measured for the photoproduction reactions producing aor anquark pair in the final state. Advanced theoretical models introducing nucleon resonances and additional unnatural-parity exchanges are needed to reproduce the present data.