Well-established nucleon resonances revisited by double-polarization measurements.
Well-established nucleon resonances revisited by double-polarization measurements.
复制标题
通过双极化测量重新审视成熟的核子共振
DOI：
10.1103/physrevlett.109.102001
复制
发表时间：
2012
影响因子：
8.6
通讯作者：
TAPS Collaboration]
中科院分区：
文献类型：
--
作者：
A. Thiel [CBELSA;TAPS Collaboration]
首次报道了在620-1120 MeV的光子能量范围和全固体角范围内，在质子光产生中性子的双偏振观测。描述了沿入射光子方向极化的质子的偏振面和散射面之间的关系。该能观量对重子共振的贡献高度敏感。将新的结果与Said、MAID和BnGa分波分析的预测进行了比较。尽管人们花了很长时间来理解最简单的光产生反应，但令人惊讶的是，新数据和最新预测之间的巨大差异可以追溯到自旋奇偶性共振和自旋奇偶性共振的不同贡献。在产量占主导地位的第三个共振区，新数据与预测相当接近。
The first measurement is reported of the double-polarization observablein the photoproduction of neutral pions off protons, covering the photon energy range from 620 to 1120 MeV and the full solid angle.describes the correlation between the photon polarization plane and the scattering plane for protons polarized along the direction of the incoming photon. The observable is highly sensitive to contributions from baryon resonances. The new results are compared to the predictions from SAID, MAID, and BnGa partial wave analyses. In spite of the long-lasting efforts to understandas the simplest photoproduction reaction, surprisingly large differences between the new data and the latest predictions are observed which are traced to different contributions of theresonance with spin parityandwith. In the third resonance region, wherewithproduction dominates, the new data are reasonably close to the predictions.