Dark Matter characterization at the LHC in the Effective Field Theory approach

We have studied the complete set of dimension 5 and dimension 6 effective operators involving scalar, fermion and vector Dark Matter (DM) to explore the possibility to distinguish these operators and characterise the spin of DM. We have found that, depending on the spin of the DM, the DM parts of the effective operators lead to a different energy dependence of the cross-sections and to different distributions of the invariant mass of the DM pair, and consequently to different missing transverse momentum (MET) and leading jet pseudorapidity distributions. Using a $\chi^2$ analysis, we found that at the LHC, with a luminosity of 300 fb$^{-1}$, certain classes of EFT operators can be distinguished from each other and, through this, it is possible to characterise the spin of DM in some cases. We have also observed a drastic difference in the efficiencies (up to two orders of magnitude) for large MET cuts scenarios with different DM spin, thus indicating that the DM discovery potential strongly depends on it. The study we perform here can be applied more generally than within the EFT paradigm, where the DM mediator is not produced on-the-mass-shell, such as the case of t-channel mediator or mediator with mass below $2M_{DM}$, where the invariant mass of the DM pair is not fixed.