Jet multiplicity spectrum in $t\bar{t}$ events in ATLAS

This poster presents a measurement of the jet multiplicity distributions in $t\bar{t}$ events using $4.7\mathrm{\ fb}^{-1}$ of data collected in proton-proton collisions at $\sqrt{s}=7$ TeV with the ATLAS detector. The analysis is performed in the single lepton channel, with one electron or muon in the final state and with four different jet $p_T$ thresholds at 25, 40, 60 and 80 GeV. The results are fully corrected for all detector effects and are compared to several Monte Carlo (MC) predictions, as well as to variations of these predictions with respect to the initial and final-state radiation modeling. The measurement allows to distinguish between different MC models and set constraints on the modeling of additional radiation.