\midheading{$Z\gamma\gamma$ production processes, 301, 306}

Processes {\tt{301}} and {\tt{306}} represent the production of a $Z$ boson
(or virtual photon for process {\tt 301}) in association with two photons.   The $Z/\gamma^*$ subsequently decays into
either an $e^+ e^-$ pair ({\tt nproc=301}) or neutrinos ({\tt nproc=306}).
Since these processes include real photons, the cross section diverges
when either of the photons is very soft or in the direction of the beam.
Thus in order to produce sensible results, the input file must supply values for both
{\tt gammptmin} and {\tt gammrapmax}. Moreover, when the parameters {\tt zerowidth}
and {\tt removebr} are set to {\tt .false.} the decay $Z \to e^- e^+$ ({\tt nproc=301})
will include photon radiation from both leptons, so that a non-zero $R(\gamma,\ell)_{min}$
({\tt Rgalmin})
should also be supplied. This will ensure that the cross section is well-defined.
Anomalous couplings are not currently implemented for these processes.
