Department of Physics, Shanghai Jiao Tong University, Shanghai 200240, People's Republic of China.
Phys Rev Lett. 2012 Oct 12;109(15):152005. doi: 10.1103/PhysRevLett.109.152005. Epub 2012 Oct 10.
We present a systematic study of the proton spin structure in terms of measurable parton distributions. For a transversely polarized proton, we derive a polarization sum rule from the leading generalized parton distributions appearing in hard exclusive processes. For a longitudinally polarized proton, we obtain a helicity decomposition from well-known quark and gluon helicity distributions and orbital angular-momentum contributions. The latter are shown to be related to measurable subleading generalized parton distributions and quantum-phase space Wigner distributions.
我们提出了一个质子自旋结构的系统研究，从可测量的部分子分布来描述。对于横向极化的质子，我们从出现于硬的单举过程中的主导广义部分子分布推导出一个极化求和规则。对于纵向极化的质子，我们从已知的夸克和胶子的自旋分布以及轨道角动量贡献中得到一个螺旋度分解。后者被证明与可测量的次领头广义部分子分布和量子相空间维格纳分布有关。
