\midheading{$W+b{\bar b}$ production, processes 20,25}
\label{subsec:wbb}

This process is calculable at leading LO and next-to-leading order NLO.
These processes represent the production of a $W$ boson which subsequently
decays leptonically, in association with a $b{\bar b}$ pair. The effect of
the bottom quark mass is included throughout the calculation.
This calculation may be performed at NLO, thanks to
the incorporation of the virtual corrections from ref.~\cite{Badger:2010mg}.
When {\tt removebr} is true, the $W$ boson does not decay.

To select final states in which one of the $b$-quarks may be unobserved the
user can employ processes \href{https://mcfm.fnal.gov/processes//process401.html}{401-408} instead.
These processes use the same matrix
elements but make specific requirements on the kinematics of the $b$-quarks
and QCD radiation.