\midheading{$Z+b{\bar b}$ production, $m_b \neq 0$, process 50}
\label{subsec:zbb}

These processes represent the production of a $Z$ boson (or virtual photon)
which subsequently decays leptonically, in association
with a $b{\bar b}$ pair. The effect of
the bottom quark mass is included throughout the calculation.
The calculation may be performed at LO only, because the one-loop
calculation with massive quarks has not yet been performed.

When {\tt removebr} is true, the $Z$ boson does not decay.