I discuss the feasibility of measuring the top quark mass by the using of
final states with leptons and J/\psi at hadron colliders. I also investigate
the impact of matrix-element corrections to the HERWIG simulation of top
decays.Comment: 4 pages, 3 figures. Talk given at the UK Phenomenology Workshop on
Collider Physics, Durham, U. K., 19-24 September 1999. Revised version with
updated result