Top-quark issues at high-energye+e−colliders

We consider the possibility that the top quark is accessible via $Z^0$→tt¯ at the SLAC Linear Collider and the CERN collider LEP. Several physics issues associated with such a large top-quark mass as $m_t$∼40 GeV are discussed: (1) fragmentation in hadronization; (2) depolarization in hadronization; (3) single-quark toponium decay; and (4) $T_{l3}^{\left(\mathrm{*}\right)}$ decay. In all cases, there may be new effects in comparison to to the various light-quark scenarios.