Caption Figure 1: The distribution of the di-muon mass (a) and the inclusive jet multiplicity (b) for signal and backgrounds in the muon channel. In order to provide higher statistics for the background determination, background events in an invariant mass window of 51−131 GeV, are scaled down for an invariant mass window of 81−101 GeV. Also shown is the distribution of pT of the leading (c) and the next-to-leading (d) jet in the electron channel for Ldt = 1 fb-1. The vertical lines in (a), (c) and (d) indicate the kinematic cuts applied in the analysis.

Caption Figure 2: Comparison of the distribution of the pT of the leading jet (a) and the next-to-leading jet (b) for the generated (hadron-level) Monte Carlo and for the reconstructed quantities without any correction, after the corrections for electron triggering and reconstruction and after applying in addition the jet-releated corrections.

Caption Figure 3: Comparison of the inclusive jet cross-section (a) and the pT of the leading jet (b) and of the next-to-leading jet (c) for the Z -> m+m- +jets channel from PYTHIA and ALPGEN Monte Carlo with NLO (LO) MCFM predictions. The MCFM predictions have been corrected to the hadron level.

Caption Figure 4: The inclusive jet cross-section (a) and the distribution of the pT of the leading jet (b), as predicted by NLO (LO) MCFM (corrected to the hadron-level) and by ALPGEN for the Z -> e+e- +jets process.

Caption Figure 5: Uncertainty on the ratio of measurement and theory for the inclusive jet cross-section (a) and the pT of the leading jet (b) for the Z -> e+e- +jets process.

Caption Table 1: The accepted cross-sections (σ , in fb) and the corresponding fraction of the total sample (in %) for signal and for the background channels in the Z->e+e- +jets and the Z->μ+μ- +jets analyses, after applying the cuts outlined in Section 3. The numbers in brackets are extrapolated from results obtained for a lower jet multiplicity. Errors shown are statistical only.