  We present an estimate of a chiral-odd contribution to the single
transverse-spin asymmetry in the large-$p_T$ pion production in the
nucleon-nucleon collision. In this contribution the transversity distribution
and the chiral-odd spin-independent twist-3 distribution appear. Because of the
smallness of the corresponding hard cross section, this term turned out to be
negligible in all kinematic regions compared with the chiral-even contribution.

High Energy Physics - Phenomenology