Measurement of Jet Multiplicity Distributions in Semileptonic Top Quark Pair Events

The normalized differential cross section of $t\bar{t}$ events in the semileptonic decay channel in jet multiplicity bins is presented, measured in proton-proton collisions using $5.0\,\text{fb}^{-1}$ of data collected at $\sqrt{s} = 7\,\text{TeV}$. Additionally, the normalized differential cross-section of top quark pair production in bins of the number of radiated additional hard partons is measured. These measurements are sensitive to additional radiation at the top quark scale. Comparisons of data with predictions from different Monte Carlo generators or using different scale values for the predictions are provided. Good agreement is observed between data and the prediction from \textsc{MadGraph} + \textsc{Pythia}.