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Top Quark Polarization in Polarized $e^+e^-$ Annihilation near Threshold

R. Harlander·M. Jezabek·J. H. Kuehn·M. Peter
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Abstract

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 be produced.

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R. Harlander, M. Jezabek, J. H. Kuehn, M. Peter. 1996-04-16. Top Quark Polarization in Polarized $e^+e^-$ Annihilation near Threshold. https://arxiv.org/abs/hep-ph/9604328

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