Gauge-invariant decomposition of nucleon spin
Gauge-invariant decomposition of nucleon spin
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DOI：
10.1088/1742-6596/295/1/012038
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发表时间：
2010-04
期刊：
影响因子：
--
通讯作者：
M. Wakamatsu
中科院分区：
文献类型：
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作者：
M. Wakamatsu
基于任意洛伦兹坐标系中 QCD 协变角动量张量的规范不变分解，我们研究了核子自旋的已知分解与其成分之间的关系，从而阐明了它们在哪些方面是共同的以及在哪些方面是关键不同的。我们认为，在合适的洛伦兹框架中进行适当的规范固定之后，Bashinsky 和 Jaffe 的分解、Chen 等人的分解以及 Jaffe 和 Manohar 的分解都包含在我们更一般的分解中，这意味着它们都是规范等效的。然而，我们指出，核子自旋还有另一种规范不变的分解，它更接近 Ji 分解，同时允许将胶子总角动量分解为其自旋和轨道部分。后一种分解的优点是，四项中的每一项都对应于一个明确的可观测值，可以从高能深层非弹性散射测量中提取。
Based on gauge-invariant decomposition of covariant angular momentum tensor of QCD in an arbitrary Lorentz frame, we investigate the relation between the known decompositions of the nucleon spin into its constituents, thereby clarifying in what respect they are common and in what respect they are different critically. We argue that the decomposition of Bashinsky and Jaffe, that of Chen et al., and that of Jaffe and Manohar are contained in our more general decomposition, after an appropriate gauge-fixing in a suitable Lorentz frame, which means that they are all gauge-equivalent. We however point out that there is another gauge-invariant decomposition of the nucleon spin, which is closer to the Ji decomposition, while allowing the decomposition of the gluon total angular momentum into its spin and orbital parts. An advantage of the latter decomposition is that each of the four terms corresponds to a definite observable, which can be extracted from high-energy deep-inelastic-scattering measurements.