Now I can understand its unlikely to see a $W$ or $Z$ boson decay into a pair of quarks that involve a top or anti-top quark simply because of the amount of energy it would require, but find it well within the realm of a theoretical possibility unbound by practical limitations considering that any particle can have enough velocity to obtain any energy level.
Wikipedia states that the branching ratios can be derived theoretically from coupling constants, so it appears that somehow the $W$ and $Z$ boson energy levels are limited. Im thinking maybe there are some assumptions that are taken to derive the branching ratios that include assuming the energy level of these bosons thereby excluding the top quark from the branching ratios.
Can someone confirm that it is or is not possible for a top or anti-top quark from being involved in a $W$ or $Z$ boson decay by stating what theoretical mechanism allows or prevents this?
Note: It sounds like since the reference frame of the boson and the decay products are the same then the total mass-energy of the products is limited to the rest mass of the Boson.