We study the Collins mechanism for the single transverse spin asymmetry in the collinear factorization approach. The correspondent twist-three fragmentation function is identified. We show that the Collins function calculated in this approach is universal. We further examine its contribution to the single transverse spin asymmetry of semi-inclusive hadron production in deep inelastic scattering and demonstrate that the transverse momentum dependent and twist-three collinear approaches are consistent in the intermediate transverse momentum region where both apply.
@article{arxiv.0903.4680,
title = {Collins Fragmentation and the Single Transverse Spin Asymmetry},
author = {Feng Yuan and Jian Zhou},
journal= {arXiv preprint arXiv:0903.4680},
year = {2009}
}