  The elastic scattering of gqq, gqqbar and gqbarqbar and the thermalization of
quark-gluon matter are studied. According to Feynman diagrams at the tree
level, squared amplitudes for the elastic gqq scattering and the elastic gqqbar
scattering are derived in perturbative QCD. Transport equations including the
squared amplitudes for the elastic gqq, gqqbar and gqbarqbar scattering are
established. Corresponding to anisotropic gluon and quark distributions created
in central Au-Au collisions at RHIC, solutions of the transport equations show
that thermalization time of quark matter can be shortened by the elastic gqq,
gqqbar and gqbarqbar scattering.
