\section{Final state radiation}
\label{sect:finalstaterad}
\index{PHOTOS}
\index{final state radiation}

To incorporate the effects of final state radiation an interface to
PHOTOS~\cite{Was92} has been added. Photos is a packaged that
generate final state photons on a generated decay. In the case of the
decay $J/\Psi\rightarrow e^{+}e^{-}$ a large fraction of the electrons
and positrons in the final state will emit one (or more) photons. 

 PHOTOS is activated in the decay file for a particular channel
by adding ``PHOTOS'' before the name of the decay model,
\begin{verbatim}
Decay J/psi
1.0000  e+ e-       PHOTOS VLL;
Enddecay
\end{verbatim}

PHOTOS is useful for radiating photons of any charged particles in the 
final state, maybe someone should try it on $B\rightarrow \pi^{+}\pi^{-}$!