Confronting the Fermi Line with LHC data: an Effective Theory of Dark Matter Interaction with Photons

We describe an effective theory of interaction between pairs of dark matter particles and pairs of photons. Such an interaction could accomodate $\chi \bar{\chi }\to \gamma \gamma$ processes which might be the cause of the observed feature in the FermiLAT spectrum, as well as ${\gamma }^{\ast }\mathrm{/}Z\to \gamma \chi \bar{\chi }$ processes, which would predict excesses at the LHC in the $\gamma +\text{missET}$ final-state. We reinterpret an ATLAS $\gamma +\text{missET}$ analysis and the observed Fermi feature in the parameter space of our new effective theory to assess their consistency.