标题： 具有适当运动学的贝特-萨尔彼得振幅得到的π介子电磁形状因子 显示英文标题

标题： Pion Electromagnetic Form Factor from Bethe-Salpeter Amplitudes with Appropriate Kinematics

摘要： 在量子色动力学的施温格-戴森方程（SDEs）框架内，利用具有有限空间动量的贝特-萨尔斯方程（BSE）解来计算π介子的电磁形式因子，从而允许给定动量转移时的适当运动学。 这首次消除了以前基于SDE计算中的一个限制性近似，即在该近似中，静止参考系下的BSE解被用于初始和最终π介子态。 在进行这些计算时，采用朗道规范下SDE的彩虹梯级截断，并用马里斯-坦迪模型给出夸克-胶子相互作用。 使用具有给定动量转移的正确空间动量的贝特-萨尔斯振幅（BSA），即$Q^2$，对π介子的电磁形式因子的结果产生了显著影响。 对于$0 \leqslant Q^2 \lesssim 1\,$GeV$^2$，使用静止参考系的BSA与具有正确运动学的BSA所得结果之间的差异小于10%，然而，随着动量转移的增加，这些修正逐渐增大，在$Q^2 \simeq 3\,$GeV$^2$时接近100%。 显示英文摘要

摘要： Within the framework provided by quantum chromodynamics's Schwinger-Dyson equations (SDEs), the pion's electromagnetic form factor is computed using solutions of the Bethe-Salpeter equation (BSE) that have finite spacial momentum, and therefore allow the appropriate kinematics for a given momentum transfer. This removes, for the first time, a limiting approximation in previous SDE calculations where rest-frame solutions to the BSE are used for both the initial and final pion states. In performing these calculations, the rainbow-ladder truncation to the SDEs in the Landau gauge is used, with the quark-gluon interaction given by the Maris-Tandy model. Using Bethe-Salpeter amplitudes (BSAs) that have the correct spacial momentum for a given momentum transfer, $Q^2$, has a dramatic impact on results for the pion's electromagnetic form factor. The difference between results that use rest-frame BSAs and those with correct kinematics is less that 10\% for $0 \leqslant Q^2 \lesssim 1\,$GeV$^2$, however, these corrections grow with increasing momentum transfer and approach 100\% for $Q^2 \simeq 3\,$GeV$^2$.