  We study the QCD evolution for the twist-three quark-gluon correlation
functions associated with the transverse momentum odd quark distributions.
Different from that for the leading twist quark distributions, these evolution
equations involve more general twist-three functions beyond the correlation
functions themselves. They provide important information on nucleon structure,
and can be studied in the semi-inclusive hadron production in deep inelastic
scattering and Drell-Yan lepton pair production in $pp$ scattering process.

High Energy Physics - Phenomenology