N→Δ跃迁广义部分子分布的多极结构
Multipole structure of the $N \to Δ$ Transition Generalized Parton Distributions
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中文总结 AI 辅助
研究N→Δ跃迁广义部分子分布的多极结构，通过协变跃迁矩阵元多极展开分解四个跃迁GPDs，在零偏斜度极限下定义碰撞参数跃迁密度，直观呈现部分子跃迁的多极结构。
中文摘要 AI 辅助
我们在广义部分子分布（GPDs）层面建立了N→Δ跃迁的多极结构。通过协变跃迁矩阵元依据三维自旋跃迁张量和横向动量转移进行多极展开，将四个跃迁GPDs在横向平面分解为一个单极、两个偶极和一个四极分量。这些多极分量与光前螺旋度振幅一一对应。在零偏斜度极限下，多极GPDs定义了碰撞参数跃迁密度，推广了横向跃迁电荷密度到依赖x的层面。这些跃迁密度源于两个不同强子态之间的非对角矩阵元，与核子和Δ的对角密度不同。多极跃迁密度直观呈现了部分子N→Δ跃迁在横向平面的单极、偶极和四极结构。
英文摘要
We establish the multipole structure of the $N \to Δ$ transition at the level of the generalized parton distributions (GPDs). We decompose the four transition GPDs into one monopole, two dipole, and one quadrupole components in the transverse plane by a multipole expansion of the covariant transition matrix element in terms of the three-dimensional spin-transition tensors and the transverse momentum transfer. These multipole components are in one-to-one correspondence with the light-front helicity amplitudes. In the zero-skewness limit, the multipole GPDs define impact-parameter transition densities, which generalize the transverse transition charge densities to the $x$-dependent level. These transition densities arise from non-diagonal matrix elements between two distinct hadronic states and must therefore be distinguished from the diagonal densities of the nucleon and the $Δ$. The multipole transition densities visualize the monopole, dipole, and quadrupole structures of the partonic $N \to Δ$ transition in the transverse plane.
