Invisible Z Estimation in the Monojet Final State

A study in jet plus missing transverse energy (MET) in the LHC has high potential for discovery of new physics. One of dominant backgrounds remaining after applying monojet event selections is invisible Z. In this work, a contribution of irreducible invisible Z background is estimated by using Z(μμ)+jets and W(μυ)+jets events. Since they are statistically uncorrelated, the final estimate is determined by taking the weighted average of the two predictions. Finally, the exclusion limit is calculated from the result.