Single-spin asymmetries at two loops
Single-spin asymmetries at two loops
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DOI：
10.1103/physrevd.100.094027
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发表时间：
2019-09
影响因子：
5
通讯作者：
S. Benić;Y. Hatta;Hsiang-nan Li;Dong-Jing Yang
中科院分区：
文献类型：
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作者：
S. Benić;Y. Hatta;Hsiang-nan Li;Dong-Jing Yang
我们发现了一种在半包含深度非弹性散射中产生横向单自旋不对称(SSA)的新机制，不同于已知的涉及Sivers和Collins函数或它们的共线扭转三对应物的机制。结果表明，SSA所需的相完全可以在从两个回路开始的部分子能级截面内产生。我们确定了SSA的两圈图的完整集合，并讨论了它们的规范不变性和具有$g_T$分布函数的共线因式分解。在$k_T$因子化框架中，存在着更多的SSA源，并且所有可能的两部分子横向动量相关的部分子分布函数的贡献最大可达两圈，扭转三圈。
We find a novel mechanism for generating transverse single-spin asymmetry (SSA) in semi-inclusive deep inelastic scattering, distinct from the known ones which involve the Sivers and Collins functions, or their collinear twist-three counterparts. It is demonstrated that a phase needed for SSA can be produced purely within a parton-level cross section starting at two loops. We identify the complete set of two-loop diagrams for SSA, and discuss their gauge invariance and collinear factorization which features the $g_T$ distribution function. In the $k_T$ factorization framework, many more sources for SSA exist, and contributions from all possible two-parton transverse-momentum-dependent parton distribution functions are presented up to two loops and twist three.