Threshold production oftt¯pairs bye+e−collisions

A two-loop QCD potential is used to study the resonance production of $t\overline{t}$ pairs. Comparison with open flavor production is made. In the intermediate region, both approaches were found to describe equally well the production process. Examples are given for $m_t=100\mathrm{} \mathrm{and} 130$ GeV. At these masses, toponia have widths of 0.2 and 1 GeV, respectively, whereas the $1S-2S$ mass difference is about 1 GeV.