A quantity of particular experimental interest is the forward-backward asymmetry in the angular distribution of positively and negatively charged fermions produced in $Z^0$ decays. Measurements of this asymmetry can enable independent determinations of the neutral-current couplings of these fermions, i.e., the $Z^0$ boson couplings for left- and right-handed fermions, respectively. Due to the quark confinement, however, it is difficult to determine the electroweak interactions of quarks, especially for light quarks. In the hadron production electron positron annihilation process, the parton model with factorization theorem gives a reliable approximate description. Quantities are thus expressed in terms of fragmentation functions in the annihilation process. In this paper, we consider the vector meson production in the inclusive electron positron annihilation process and calculate the forward-backward asymmetry in the hadronic level. Calculations are carried out by applying the collinear expansion in the parton model at leading order twist-4. We note here this process provides not only a tool for analyzing the hadronic weak interactions but also an opportunity for understanding the parton model of the strong interaction. In other words, the results can be used to test the electroweak and strong interactions simultaneously.

中文翻译：

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扭曲4处电子正电子湮没过程中的前后不对称

一个特别令人感兴趣的实验是在$Z^0$衰变。这种不对称性的测量可以独立确定这些费米子的中性电流耦合，即$Z^0$分别用于左手和右手费米子的玻色子耦合。然而，由于夸克的限制，很难确定夸克的电弱相互作用，特别是对于轻夸克。在强子产生电子正电子湮灭过程中，具有因式分解定理的分子模型给出了可靠的近似描述。因此，数量以湮灭过程中的碎片函数表示。在本文中，我们考虑了包含电子正电子湮没过程中的矢量介子产生，并计算了强子能级的前后不对称性。通过在parton模型中以前导twist-4应用共线展开来进行计算。我们在这里注意到这个过程不仅提供了分析强子弱相互作用的工具，而且还提供了理解强相互作用的分子模型的机会。换句话说，结果可用于同时测试弱电和强相互作用。