Revisiting Combinatorial Ambiguities at Hadron Colliders with MT2
  We present a method to resolve combinatorial issues in multi-particle final states at hadron colliders. The use of kinematic variables such as MT2 and invariant mass significantly reduces combinatorial ambiguities in the signal, but at a cost of losing statistics. We illustrate this idea with gluino pair production leading to 4 jets $+\met$ in the final state as well as $t\bar{t}$ production in the dilepton channel. Compared to results in recent studies, our method provides greater efficiency with similar purity 
Philip Baringer, Kyoungchul Kong, Mathew McCaskey, Daniel Noonan
hep-ph hep-ex