光前夸克模型中的衍射矢量介子产生
Diffractive Vector-Meson Production from the Light-Front Quark Model
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- Institute of Physics, Academia Sinica（台湾中央研究院物理研究所）
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中文总结 AI 辅助
本研究在色偶极子图像中，利用两种光前波函数预测衍射矢量介子产生，并与实验比较，发现S-1适合轻介子，S-2适合粲偶素比率和衰变常数。
中文摘要 AI 辅助
我们在色偶极子图像中，利用两种自旋轨道光前波函数S-1和S-2，研究了ρ^0、φ、J/ψ和ψ(2S)介子的排他性衍射电产生。S-1源自光前夸克模型（LFQM）中的Melosh-Wigner旋转，而S-2是通常在全息和增强高斯方法中使用的自旋改进形式。两者共享相同的径向波函数，其参数由LFQM哈密顿量确定。色玻璃凝聚偶极子参数由非弹性结构函数数据固定，未对衍射数据进行拟合。我们将预测与截面、R=σ_L/σ_T、t和W依赖性以及σ_φ/σ_ρ的测量结果进行比较。S-1更好地描述了轻介子观测量，而S-2更好地描述了粲偶素比率σ_ψ(2S)/σ_J/ψ和J/ψ衰变常数。我们还给出了四种介子的电荷、磁和四极形状因子，并与可用的格点QCD结果进行了比较。
英文摘要
We study exclusive diffractive electroproduction of the $ρ^0$, $ϕ$, $J/ψ$, and $ψ(2S)$ mesons in the color-dipole picture using two spin-orbit light-front wave functions, S-1 and S-2. S-1 follows from the Melosh--Wigner rotation in the light-front quark model (LFQM), while S-2 is the spin-improved form commonly used in holographic and boosted-Gaussian approaches. Both share the same radial wave function, with their parameters determined from the LFQM Hamiltonian. The color-glass-condensate dipole parameters are fixed from inclusive structure-function data, with no fit to diffractive data. We compare the predictions with measurements of cross sections, $R=σ_L/σ_T$, $t$ and $W$ dependences, and $σ_ϕ/σ_ρ$. S-1 gives a better description of the light-meson observables, while S-2 provides a better description of the charmonium ratio $σ_{ψ(2S)}/σ_{J/ψ}$ and the $J/ψ$ decay constant. We also present the charge, magnetic, and quadrupole form factors of the four mesons and compare them with available lattice-QCD results.
