Nontrivial dark matter scenarios at the energy frontier

With the only guideline being the existence of dark-matter (DM), searches for dark-matter at the Large Hadron Collider (LHC) have taken a model-independent approach. In this regard, the LHC search strategy is based on the very minimal assumption of a missing transverse energy (MET) from undetected dark-matter with a Jet from Initial State Radiation (ISR). Together with this minimal search strategy, the effective operators or "simplified" models have been used to interpret the LHC results, but those general approaches cannot cover interesting DM scenarios, for example, the very light dark-matter or co-annihilation region of DM parameter space. In this letter, we review the limits of those conventional methods and present a method that can capture very light DM scenarios and probe the DM co-annihilation region.