Polarized Heavy Quarks

Polarization studies for heavy quarks can lead to important tests of the Standard Model. Top quark pair production in $e^+e^-$ annihilation is considered near energy threshold. It is shown that for longitudinally polarized electrons the produced top quarks and antiquarks are highly polarized. Dynamical effects originating from strong interactions in the $t-\bar t$ system can be calculated using Green function method. Energy-angular distributions of leptons in semileptonic decays of polarized heavy quarks are sensitive to both the polarization of the decaying quark and V-A structure of the weak charged current. Some applications to $b$ quark physics at the $Z^0$ resonance are briefly reviewed.