Model-independent approaches for the analysis of scenarios with new fermions at the LHC

New heavy fermions (both quarks and leptons) are predicted in various scenarios of new physics; depending on their nature they can mix with SM fermions or they can even mediate the production of dark matter states. However, experimental searches at the LHC have not detected any signal of new fermions so far and therefore mass bounds are provided. These bounds are computed by considering minimal extensions of the SM, with just one new fermion and with specific assumptions about its coupling patterns. A reinterpretation of these bounds in the context of theoretical models, which usually contain multiple new fermions with general couplings is therefore not always straightforward.
I will describe model independent methods to recast data from experimental searches. These methods can be used to test general scenarios with any number of extra fermions which can mix with all SM families or couple to dark matter. I will also discuss the complementarity between constraints from the LHC and different observables.