Quark-parton models and hadron structure

1.Q^2演化方程我们编制了求解Altarelli-Parisi Q^2演化方程的计算机程序。首先，研究了Laguerre多项式方法。我们发现，只有20多项式是足够的，以获得准确的演化结果。接下来，研究蛮力方法。在该方法中，变量x和Q^2被分成小的步长，然后简单地计算微分和积分。我们发现，2000 x步骤和200 Q^2步骤是必要的，以获得准确的结果。与实验数据相比，我们明确地表明，在小Q^2区，高扭曲效应是重要的。2.原子核中的部分子分布[（u-d）_A，F_<A（1）3>（x）]考虑到原子核中的部分子复合效应，我们发现不确定的相互作用可以产生有限的u-d分布，即使它在核子中消失。因此，我们在比较不清楚的Drell-Yan数据与NMC数据时必须小心。其次，我们用两种不同的描述：部分子复合模型和排列喷注模型研究了F_3结构函数中的阴影效应。我们发现它们在小x下给出了非常不同的预言，以便将来的实验可以检验它们。3.核子NMC中的反夸克分布u-d对Gottfried求和规则破坏的发现表明了u和d之间的差异。许多论文发表在这个主题上。我写了一篇总结论文，并提交给了《物理报告》。

1.Q^2 evolution equation We developed a computer program for solving the Altarelli-Parisi Q^2 evolution equations. First, a Laguerre-polynomial method is studied. We find that merely twenty polynomials are enough for obtaining accurate evolution results. Next, a brute-force method is investigated. In this method, the variables x and Q^2 are divided into small steps, then differentiation and integration are simply calculated. We find that 2000 x steps and 200 Q^2 steps are necessary for getting accurate results. We explicitly showed that higher-twist effects are important in the small Q^2 region in comparison with experimental data. The method was applied to the polarized structure function g_1.2.Parton distributions in nuclei [(u-d)_A, F_<A(1)3>(x)] Considering parton recombination effects in a uncleus, we find that unclear interactions could create a finite u-d distribution even it vanishes in the nucleon. Therefore, we have to be careful in comparing unclear Drell-Yan data with the NMC data. Next, shadowing in the F_3 structure function is investigated by using two different descriptions : parton-recombination and aligned-jet models. We find that they give very different predictions at small x, so that they could be tested by future experiments.3.Antiquark distribution u-d in the nucleon NMC finding of the Gottfried sum rule violation indicated the difference between u and d. Many papers are published on this topic. I wrote a summary paper and submitted it to Physics Reports.