论文标题
$π^0 $对的光生生源的螺旋依赖性横截面来自核子
Helicity-dependent cross sections for the photoproduction of $π^0$ pairs from nucleons
论文作者
论文摘要
双极化可观察的$ E $和Helicity依赖的横截面$σ_{1/2} $，$σ_{3/2} $是通过Mainz Mami Accelerator在Mainz Mami Accelerator的Quasi-Free Protons和Mainz Mami Accelerator搭配Crystal Ball/Taps Setup Setup的$ free-Free Protons和Neutrons的$π^0 $配对的测量测量的。 Bremsstrahlung从纵向极化电子中产生了圆形极化的光子束，并撞击了纵向极化的氘代丁醇靶标。用近4π$覆盖量热计检测到反应产物。结果首次揭示了$γn\ rightarrownπ^0π^0 $反应的螺旋性和同胞依赖性结构。鉴于核子共振贡献的贡献，将它们与反应模型的预测进行了比较，并与一个预测质子和中子目标结果的模型进行了翻新。预测和翻新的比较证明了新数据的巨大影响。
The double-polarization observable $E$ and helicity-dependent cross sections $σ_{1/2}$, $σ_{3/2}$ have been measured for the photoproduction of $π^0$ pairs off quasi-free protons and neutrons at the Mainz MAMI accelerator with the Crystal Ball/TAPS setup. A circularly polarized photon beam was produced by bremsstrahlung from longitudinally polarized electrons and impinged on a longitudinally polarized deuterated butanol target. The reaction products were detected with an almost $4π$ covering calorimeter. The results reveal for the first time the helicity- and isospin-dependent structure of the $γN\rightarrow Nπ^0π^0$ reaction. They are compared to predictions from reaction models in view of nucleon resonance contributions and also to a refit of one model that predicted results for the proton and for the neutron target. The comparison of the prediction and the refit demonstrate the large impact of the new data.
