Abstract and subjects
At RHIC energy, heavy flavor production is dominated by gluon-gluon fusion, so the Collins effect has minimum impact on transverse single spin asymmetry (A{sub N}) as the gluon's transversity is zero. The measurement of A{sub N} in heavy flavor production is sensitive to the gluon Sivers distribution which is related to the orbital angular momentum of gluons inside the polarized protons. The most recent results of A{sub N} in J/{psi} and open heavy flavor production at forward rapidity are presented.