Z polarization in $gammagamma$,gluon-gluon $to tbar t Z$ for testing the top quark mass structure and the presence of final interactions

We show what type of effects on the rate of $Z_L$ production in the $gammagammato tbar t Z$ and $gluon~gluonto tbar t Z$ processes could be produced by an effective scale dependent top mass or by final state interactions between massive particles for example generated by the presence of dark matter.