Transverse spin asymmetries at COMPASS: beyond Collins and Sivers effects
Transverse spin asymmetries at COMPASS: beyond Collins and Sivers effects
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COMPASS 处的横向自旋不对称性：超越柯林斯和西弗斯效应
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发表时间：
2013
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通讯作者：
B. Parsamyan
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作者：
B. Parsamyan
COMPASS实验（SPS，CERN）引用{Abbon：2007 pq}的重要目标之一是通过极化轻子离开横向极化靶的深度非弹性散射中的单强子产生中的自旋相关方位角不对称性来探索核子的横向自旋结构。为此，在COMPASS中进行了一系列测量，使用160 GeV/c纵向极化μ子束和横向极化$^6LiD$（2002年、2003年和2004年）和$NH_3$（2007年和2010年）靶。
在过去的几年里，人们对柯林斯和Sivers横向自旋不对称性的研究引起了相当大的理论兴趣和实验努力。到目前为止，所获得的实验结果发挥了重要作用，在一般理解的三维性质的核子的横向动量相关的部分子分布函数。
除了这两个测量的领先扭曲的影响，SIDIS截面包括六个目标横向自旋相关的方位角不对称性，有自己的定义良好的领先或更高的扭曲解释的QCD部分子模型。
从横向极化的氘核和质子数据中获得的这六个“超越柯林斯和西弗斯”不对称性的COMPASS初步结果已经在以前的会议上发表。在这篇综述中，我们重点介绍了最后一个“质子-2010”数据样本所获得的结果。
One of the important objectives of the COMPASS experiment (SPS, CERN) cite{Abbon:2007pq} is the exploration of the transverse spin structure of the nucleon via spin dependent azimuthal asymmetries in single-hadron production in deep inelastic scattering of polarized leptons off transversely polarized targets. For this purpose a series of measurements were made in COMPASS, using 160 GeV/c longitudinally polarized muon beam and transversely polarized $^6LiD$ (in 2002, 2003 and 2004) and $NH_3$ (in 2007 and 2010) targets.
In the past few years considerable theoretical interest and experimental efforts were focused on the study of Collins and Sivers transverse spin asymmetries. The experimental results obtained so far play an important role in the general understanding of the three-dimensional nature of the nucleon in terms of transverse momentum dependent parton distribution functions.
In addition to these two measured leading-twist effects, the SIDIS cross-section includes six more target transverse spin dependent azimuthal asymmetries, which have their own well defined leading or higher-twist interpretation in terms of QCD parton model.
COMPASS preliminary results for these six "beyond Collins and Sivers" asymmetries, obtained from transversely polarized deuteron and proton data have been presented at the previous conferences cite{Parsamyan:2007ju} - cite{Parsamyan:2013ug}. In this review we focus on the results obtained with the last "proton-2010" data sample.