Flavor-changing neutral current constraints in topcolor-assisted technicolor

It is pointed out that flavor-changing neutral current processes (such as B - B mixing) can be sensitive to the dynamics of the topcolor models recently proposed by Hill [Phys. Lett. B 345 (1995) 483], unless at least some of the mixing angles between down-type quarks are suppressed. The flavor-changing processes are mediated by scalar bound states which are likely to be light as a result of the near critical dynamics of the b-quark sector. The consequences of the latter on the bottom quark mass are also briefly discussed.