SINGLE QUARK POLARIZATION IN QUANTUM CHROMODYNAMICS SUBPROCESSES

It is well known that the single-polarization asymmetries vanish in QC D with massless quarks. But, heavy quarks with a nonzero mass should b e transversely polarized due to the breakdown of the helicity conserva tion. In this paper we give the exact fourth-order perturbative QCD pr edictions for the transverse polarization from all QCD subprocesses, q (+)q' --> q+q', g+g --> q+g, g+g --> q+(q) over bar, and q+(q) over ba r --> q'+(q) over bar', which are significant for heavy quark producti on, with a description of the method of calculation. The kinematical d ependence of the polarization is discussed. Top quark polarization fro m gluon fusion and quark annihilation processes, which are the importa nt subprocesses at high energies, is estimated and its significance is discussed.