Master formula for twist-3 soft-gluon-pole mechanism to single transverse-spin asymmetry
Master formula for twist-3 soft-gluon-pole mechanism to single transverse-spin asymmetry
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DOI：
10.1016/j.physletb.2007.01.044
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发表时间：
2006-12
影响因子：
4.4
通讯作者：
Y. Koike;Kazuhiro Tanaka
中科院分区：
文献类型：
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作者：
Y. Koike;Kazuhiro Tanaka
微扰QCD将产生粒子的大横动量下的硬过程的单横自旋不对称性（SSA）与部分子矩阵元联系起来，部分子矩阵元描述了相干夸克-胶子对散射与单个夸克散射之间的干涉，这些散射是通过强子内部的扭曲3夸克-胶子关联产生的。当相干胶子在胶子极点处是软的时，它与部分子过程的耦合可以被系统地解除纠缠，从而可以完全从单个夸克散射的玻恩图导出相关的干涉振幅。我们建立了一个新的公式，代表的确切规则，推导出由于软胶子极点的非极化过程的扭曲-2截面公式的知识SSA。这个主公式适用于一系列过程，如Drell-Yan和直接光子产生，以及半包含的深度非弹性散射，并且也有助于表明结果的规范不变性。
Perturbative QCD relates the single transverse-spin asymmetries (SSAs) for hard processes at large transverse-momentum of produced particle to partonic matrix elements that describe interference between scattering from a coherent quark–gluon pair and from a single quark, generated through twist-3 quark–gluon correlations inside a hadron. When the coherent gluon is soft at the gluonic poles, its coupling to partonic subprocess can be systematically disentangled, so that the relevant interfering amplitude can be derived entirely from the Born diagrams for the scattering from a single quark. We establish a new formula that represents the exact rules to derive the SSA due to soft-gluon poles from the knowledge of the twist-2 cross-section formula for unpolarized processes. This single master formula is applicable to a range of processes like Drell–Yan and direct-photon production, and semi-inclusive deep inelastic scattering, and is also useful to manifest the gauge invariance of the results.