arXiv subjects
Publications and source records attributed to M. Jezabek.
Recent calculations are presented of top quark polarization in $t\bar t$ pair production close to threshold. S-P-wave interference gives contributions to all components of the top quark polarization vector. Rescattering of the decay products is considered. Moments of the fourmomentum of the charged lepton in semileptonic top decays are calculated and shown to be very sensitive to the top quark polarization.
Top quark production in $p\bar p$ and $e^+e^-$ collisions is enhanced by the exchange of a Higgs boson. The enhancement factors are calculated in the threshold region using the Greens function method.
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.
We point out that an apparent discrepancy between the values of $α_s(M_z)$ as determined from low versus high energy experiments can be explained if an electrically neutral coloured fermion exists which slows down the running of the strong coupling constant $α_s$.