Measurement of the Underlying Event Activity with the Jet Area/Median Approach at 0.9 TeV

In this study, the first measurement of the charged component of the Underlying Event using the recently proposed jet area/median approach is presented for proton-proton collisions at $\sqrt{s} = 0.9$\,TeV. The sensitivity to different generator tunes is demonstrated for charged particle jets after applying detector specific selection criteria and thresholds. The subsequent comparison of uncorrected CMS data with predictions of different Underlying Event models after detector simulation reveals significant discrepancies indicating the need for improved tunes of the Monte Carlo event generators. The general pattern of deviations looks similar to the one observed with more traditional methods.