论文标题
关于手性twist-3 parton分布E（x）的奇异行为
On the Singular Behavior of the Chirality-Odd Twist-3 Parton Distribution e(x)
论文作者
论文摘要
第一刻，手性odd twist-3 parton分布$ e（x）$与pion-nucleon $σ$ - term有关，这对现象学很重要。但是，在分布中，与$δ（x）$成比例的唯一贡献可能存在于实验中用$ e（x）$的$σ$ term确定。有两种显示存在的方法。第一个是基于操作员身份。第二个是基于具有有限夸克质量的单个夸克状态的扰动计算。我们表明，实际上已取消了第一种方法中与$δ（x）$成比例的所有贡献。在第二种方法中，我们发现具有无数夸克的多方状态的$ e（x）$没有$δ（x）$的贡献。考虑到质子本质上是多方状态，因此预计用$δ（x）$的贡献的效果被带有扰动理论的参数的光夸克质量抑制。提供了有关$ e（x）$的切割图和未切割图之间差异的详细讨论。
The first moment the chirality-odd twist-3 parton distribution $e(x)$ is related to the pion-nucleon $σ$-term which is important for phenomenology. However, the possible existence of a singular contribution proportional to $δ(x)$ in the distribution prevents from the determination of the $σ$-term with $e(x)$ from experiment. There are two approaches to show the existence. The first one is based on an operator identity. The second one is based on a perturbative calculation of a single quark state with finite quark mass. We show that all contributions proportional to $δ(x)$ in the first approach are in fact cancelled. To the second approach we find that $e(x)$ of a multi-parton state with a massless quark has no contribution with $δ(x)$. Considering that a proton is essentially a multi-parton state, the effect of the contribution with $δ(x)$ is expected to be suppressed by light quark masses with arguments from perturbation theory. A detailed discussion about the difference between cut- and uncut diagrams of $e(x)$ is provided.
