A Study of Simplified Models for Dark Matter Searches in pp Collisions

A study of different model approaches for missing E/T searches in the mono-lepton channel with a lepton plus E/T in the final state. In the first part of this analysis dark matter is considered to be a Majorana fermion. It is found, that compared to the usual Dirac fermion approach there is no difference regarding the kinematics but a difference of a factor of two on the cross section in the Majorana case. A short analysis of non integer coupling values for the mediators coupling to quarks shows, that this provides no fundamental changes for the process’s kinematics. Further, the interference, which is described by a parameter ξ, is analyzed. In contrast to an EFT, where cases of unequal couplings to up and down type quarks have been restricted, one finds a rather different behavior of the simplified model, when it comes to gauge invariance and unitarity. It is found, that this difference of behavior opens the cases ξ = −1, 0 for a simplified model within a certain range of validity.