Single Transverse Spin Asymmetry in $p^{\uparrow }p\to \pi X$ and $e{p}^{\uparrow }\to \pi X$

Abstract

Single transverse spin asymmetry for the pion production in pp and ep collisions is studied in the framework of collinear factorization. The soft-gluon pole contributions with twist-3 distribution and fragmentation functions are identified and its characteristic features are discussed.

Comments: 4 pages in LaTex. Talk presented at PANIC2002, Sep. 30 - Oct. 4, 2002, Osaka, Japan