Single-spin asymmetries in semi-inclusive deep-inelastic scattering on a transversely polarized hydrogen target.
Single-spin asymmetries in semi-inclusive deep-inelastic scattering on a transversely polarized hydrogen target.
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DOI：
10.1103/physrevlett.94.012002
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发表时间：
2004-08
影响因子：
8.6
通讯作者：
The Hermes Collaboration
中科院分区：
文献类型：
--
作者：
The Hermes Collaboration
首次利用横向目标极化测量了正电子深非弹性散射中带电π介子半包容电产生的单自旋不对称性。不对称性取决于介子 (phi) 和目标自旋轴 (phi(S)) 围绕虚光子方向并相对于轻子散射平面的方位角。提取的傅立叶分量 sin((phi+phi(S))(pi)(UT) 是先前未测量的夸克横断分布的信号，与同样未知的柯林斯碎裂函数相结合。分量 sin((phi-phi(S)(pi)(UT) 源自目标核子的横向极化与夸克的固有横向动量之间的相关性，如以下所示 以前未测量的 Sivers 分布函数。观察到两个信号的证据，但西弗斯不对称性可能受到排他性矢量介子产生的影响。
Single-spin asymmetries for semi-inclusive electroproduction of charged pions in deep-inelastic scattering of positrons are measured for the first time with transverse target polarization. The asymmetry depends on the azimuthal angles of both the pion (phi) and the target spin axis (phi(S)) about the virtual-photon direction and relative to the lepton scattering plane. The extracted Fourier component sin((phi+phi(S))(pi)(UT) is a signal of the previously unmeasured quark transversity distribution, in conjunction with the Collins fragmentation function, also unknown. The component sin((phi-phi(S)(pi)(UT) arises from a correlation between the transverse polarization of the target nucleon and the intrinsic transverse momentum of quarks, as represented by the previously unmeasured Sivers distribution function. Evidence for both signals is observed, but the Sivers asymmetry may be affected by exclusive vector meson production.