Upper bounds on the top quark mass from Bsub(s)-anti Bsub(s) mixing

When one succeeds in obtaining experimental limits on Bsub(s)-anti Bsub(s) mixing, then one can place rather conservative bounds on the top quark mass. For example, non-maximal mixing of Bsub(s) mesons would imply m(top) <= 90 GeV. Such connections between Δm(Bsub(s)) and m(top) exist strictly only within the standard model with three families, yet will very likely hold also in a four-family ansatz. (orig.)