e+e-</EM> Annihilation near Threshold > Top quark polarization in $e^+e^-$ annihilation into $t\bar t$
is calculated for linearly polarized beams.
The Green function formalism is applied
to this reaction near threshold.
The Lippmann–Schwinger equations for the $S$-wave and
$P$-wave Green functions are solved numerically for the
QCD chromostatic potential given by the two-loop formula
for large momentum transfer and Richardson's ansatz
for intermediate and small momenta.
$S$-$P$–wave interference contributes to all
components of the top quark polarization vector. Rescattering of
the decay products is considered.
The mean values $\langle n \ell \rangle$
of the charged lepton four-momentum projections on appropriately chosen
directions $n$ in semileptonic top decays are proposed as experimentally
observable quantities sensitive
to top quark polarization.
The results for $\langle n \ell \rangle$ are obtained
including $S$-$P$–wave interference and rescattering of the decay
products.
It is demonstrated that for the longitudinally polarized
electron beam a highly polarized sample of top quarks can