Single top quark polarization at O(alpha_s) in t t-bar production at a polarized linear e^+ e^- collider

We present a detailed investigation of the NLO polarization of the top quark in t t-bar production at a polarized linear e^+ e^- collider with longitudinally polarized beams. By appropiately tuning the polarization of the beams one can achieve close to maximal values for the top quark polarization over most of the forward hemisphere for a large range of energies. This is quite welcome since the rate is largest in the forward hemisphere. One can also tune the beam polarization to obtain close to zero polarization over most of the forward hemisphere.