Nikhef Theory Group, Science Park 105, 1098XG Amsterdam, The Netherlands.
Phys Rev Lett. 2012 Jun 15;108(24):242003. doi: 10.1103/PhysRevLett.108.242003. Epub 2012 Jun 13.
The Sivers transverse single spin asymmetry (TSSA) is calculated and compared at different scales using the transverse-momentum-dependent (TMD) evolution equations applied to previously existing extractions. We apply the Collins-Soper-Sterman (CSS) formalism, using the version recently developed by Collins. Our calculations rely on the universality properties of TMD functions that follow from the TMD-factorization theorem. Accordingly, the nonperturbative input is fixed by earlier experimental measurements, including both polarized semi-inclusive deep inelastic scattering (SIDIS) and unpolarized Drell-Yan (DY) scattering. It is shown that recent preliminary COMPASS measurements are consistent with the suppression prescribed by TMD evolution.
使用横向动量依赖（TMD）演化方程对先前存在的提取进行计算和比较，计算并比较了 Sivers 横向单自旋不对称性（TSSA）在不同标度下的情况。我们应用 Collins-Soper-Sterman（CSS）形式主义，使用 Collins 最近开发的版本。我们的计算依赖于 TMD 函数的普遍性，这些普遍性来自于 TMD 因子化定理。相应地，非微扰输入由早期的实验测量固定，包括极化半单举深非弹性散射（SIDIS）和非极化 Drell-Yan（DY）散射。结果表明，最近的 COMPASS 初步测量结果与 TMD 演化规定的抑制相一致。
