爱因斯坦-膨胀子全息QCD中矢量介子的电磁形状因子
Electromagnetic form factors of vector mesons in Einstein-dilaton holographic QCD
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中文总结 AI 辅助
该研究在全息QCD框架下计算ρ介子家族的电磁形状因子，弹性结果与格点QCD相符，跃迁结果为预言，并发现零点、选择定则及新求和规则。
中文摘要 AI 辅助
我们在基于爱因斯坦-膨胀子引力且具有禁闭背景的全息QCD框架内，研究了ρ介子家族的电磁形状因子。我们利用三点同位旋流关联函数的谱分解以及基于Kaluza-Klein展开的独立方法，获得了弹性形状因子和跃迁形状因子。此外，我们建立了电流矩阵元的一个全息词典。弹性形状因子与现有的格点QCD结果一致，而跃迁形状因子在格点QCD中尚未确定，是本模型的预言。对于弹性情形，ρ介子家族的电形状因子在q²=6m_{ρⁿ}²处出现零点，特别是基态在q²=3.61 GeV²处，这与光前和Dyson-Schwinger计算一致。我们还计算了矢量介子态之间的强耦合，并发现了一些近似的选择定则。在弹性情形和低q²区域，我们计算了无量纲电半径、磁矩和四极矩，并与其他方法进行了比较。在高q²区域，形状因子遵循预期的标度行为，模型预言了它们的渐近归一化。高q²区域的结果导致了超收敛关系，并建立了一个涉及质量、衰变常数和耦合的新求和规则。
英文摘要
We investigate the electromagnetic form factors of the $ρ$ meson family within a holographic QCD framework based on Einstein-dilaton gravity with confining backgrounds. We obtain the elastic and transition form factors using a spectral decomposition of the three-point isospin current correlator and an independent approach based on the Kaluza-Klein expansion. Furthermore, we establish a holographic dictionary of the current matrix element. The elastic form factors are in agreement with available lattice QCD results, whereas the transition form factors, not yet determined within lattice QCD, are predictions of the model. For the elastic case, the electric form factor for the $ρ$ meson family exhibits a zero at $q^{2} = 6\, m_{ρ^{n}}^{2}$ and in particular for the ground state $q^{2} = 3.61\,\text{GeV}^{2}$, consistent with light-front and Dyson-Schwinger calculations. We also compute strong couplings between vector meson states and find some approximate selection rules. In the elastic case and low-$q^{2}$ regime, we calculate dimensionless electric radius, magnetic and quadrupole moments and compare with other approaches. In the high-$q^{2}$ regime, the form factors follow the expected scaling behavior, and the model predicts their asymptotic normalization. The results in the high-$q^{2}$ regime lead to superconvergence relations and establish a new sum rule involving masses, decay constants and couplings.
发表机构
- Universidade Federal do Rio de Janeiro（里约热内卢联邦大学）
- Instituto Tecnológico de Aeronáutica（航空技术研究所）
- Universidade Federal do Recôncavo da Bahia（巴伊亚腹地联邦大学）
- Universidade Estadual de Santa Cruz（圣克鲁斯州立大学）
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