Abstract Not Provided.

The inclusive production of $b$-jets with a $Z$ boson is an important background to searches for the Higgs boson in associated $ZH \rightarrow llb\bar{b}$ production at the Fermilab Tevatroncollider. This thesis describes the most precise measurement to date of the ratio of inclusive cross sections $\sigma(p\bar{p} \rightarrow Z+b$-jet$)/\sigma(p\bar{p} \rightarrow Z+$jet$)$ when a $Z$ boson decays into two electrons or muons. The measurement uses a data sample from $p\bar{p}$ collisions at the center of mass energy $\sqrt{s}=1.96$ TeV corresponding to an integrated luminosity of 4.2 fb$^{-1}$ collected by the D0 detector. The measured ratio $\sigma(Z+b$-jet$)/\sigma(Z+$jet$)$ is $0.0187\pm0.0021(stat.) \pm0.0015(syst)$ for jets with transverse momentum $p_T$~$>$~20 GeV and pseudorapidity $\eta\leq$2.5. The measurement is compared with the next-to-leading order theoretical predictions from MCFM and is found to be consistent within uncertainties.

Measurements of the inclusive jet cross section with the anti-kt clustering algorithm are presented for two radius parameters, R=0.5 and 0.7. They are based on data from LHC proton-proton collisions at $\sqrt{s}$ = 7 TeV corresponding to an integrated luminosity of 5.0 inverse femtobarns collected with the CMS detector in 2011. The ratio of these two measurements is obtained as a function of the rapidity and transverse momentum of the jets. Significant discrepancies are found comparing the data to leading-order simulations and to fixed-order calculations at next-to-leading order, corrected for nonperturbative effects, whereas simulations with next-to-leading-order matrix elements matched to parton showers describe the data best.