\bottomheading{Vector mediator, processes 800 and 820}

800~$ V\to({\chi}(p_3)+\bar{\chi}(p_4)) +f(p_5) $ [Vector Mediator]  NLO \\
820~$V\to({\chi}(p_3)+\bar{\chi}(p_4)) +\gamma(p_5)$ [Vector Mediator]  NLO

Processes 800 and 820 produce the 
mono-jet or mono-photon signature through the following vector operator, 
\begin{eqnarray}
\mathcal{O}_V=\frac{(\overline{\chi}\gamma_{\mu}\chi)(\overline{q}\gamma^{\mu}q)}{\Lambda^2}~,\label{eq:OV}  
\end{eqnarray}
These processes are available at NLO and include the usual treatment of photons. See for instance the $V\gamma$ 
processes ($\sim$ 300) in this 
manual for more details on photon setup in MCFM. As discussed above the code will calculate left and right-handed 
helicity amplitudes and build the 
vector operators from $(L+R)$. Therefore you should ensure that the Left and right-handed couplings are equal in  {\tt 
dm\_parameters.DAT}. 
Processes 840 and 845 represent the production of DM plus two jets or DM plus one jet and one photon and are available 
at LO.