We present cross section measurements for Z/?* + jets + X production, differential in the transverse momenta of the three leading jets. The data sample was collected with the D0 detector at the Fermilab Tevatron p{bar p} collider at a center-of-mass energy of 1.96 TeV and corresponds to an integrated luminosity of 1 fb−1. Leading and next-to-leading order perturbative QCD predictions are compared with the measurements, and agreement is found within the theoretical and experimental uncertainties. We also make comparisons with the predictions of four event generators. Two parton-shower-based generators show significant shape and normalization differences with respect to the data. In contrast, two generators combining tree-level matrix elements with a parton shower give a reasonable description of the shapes observed in data, but the predicted normalizations show significant differences with respect to the data, reflecting large scale uncertainties. For specific choices of scales, the normalizations for either generator can be made to agree with the measurements.

In this study, a comparison of the differential cross sections for the processes Z/[gamma] * + jets and photon ([gamma])+jets is presented. The measurements are based on data collected with the CMS detector at √s = 8 TeV corresponding to an integrated luminosity of 19.7 fb-1. The differential cross sections and their ratios are presented as functions of pT. The measurements are also shown as functions of the jet multiplicity. Differential cross sections are obtained as functions of the ratio of the Z/[gamma]* pT to the sum of all jet transverse momenta and of the ratio of the Z/[gamma]* pT to the leading jet transverse momentum. The data are corrected for detector effects and are compared to simulations based on several QCD calculations.

We present cross section measurements for Z/[gamma]* + jets + X production, differential in the transverse momenta of the three leading jets. The data sample was collected with the D0 detector at the Fermilab Tevatron p{bar p} collider at a center-of-mass energy of 1.96 TeV and corresponds to an integrated luminosity of 1 fb−1. Leading and next-to-leading order perturbative QCD predictions are compared with the measurements, and agreement is found within the theoretical and experimental uncertainties. We also make comparisons with the predictions of four event generators. Two parton-shower-based generators show significant shape and normalization differences with respect to the data. In contrast, two generators combining tree-level matrix elements with a parton shower give a reasonable description of the shapes observed in data, but the predicted normalizations show significant differences with respect to the data, reflecting large scale uncertainties. For specific choices of scales, the normalizations for either generator can be made to agree with the measurements.

We present measurements of differential cross sections in inclusive Z/[gamma]* plus jet production in a data sample of 1 fb−1 collected with the D0 detector in proton antiproton collisions at √s = 1.96 TeV. Measured variables include the Z/[gamma]* transverse momentum (p{sub T}{sup Z}) and rapidity (y{sup Z}), the leading jet transverse momentum (p{sub T}{sup jet}) and rapidity (y{sup jet}), as well as various angles of the Z+jet system. We compare the results to different Monte Carlo event generators and next-to-leading order perturbative QCD (NLO pQCD) predictions, with non-perturbative corrections applied.

This Ph. D. thesis presents the measurement of inclusive jet cross sections in Z/[gamma]* 2!ee− events using 1.7 fb−1 of data collected by the upgraded CDF detector during the Run II of the Tevatron. The Midpoint cone algorithm is used to search for jets in the events after identifying the presence of a Z/[gamma]* boson through the reconstruction of its decay products. The measurements are compared to next-to-LO (NLO) pQCD predictions for events with one and two jets in the final state. The perturbative predictions are corrected for the contributions of non-perturbative processes, like the underlying event and the fragmentation of the partons into jets of hadrons. These processes are not described by perturbation theory and must be estimated from phenomenological models. In this thesis, a number of measurements are performed to test different models of underlying event and hadronization implemented in LO plus parton shower Monte Carlo generator programs. Chapter 2 is devoted to the description of the theory of strong interactions and jet phenomenology at hadron colliders. Chapter 3 contains the description of the Tevatron collider and the CDF detector. The analysis is described in detail in Chapter 4. Chapter 5 shows the measurement of those observables sensitive to non-perturbative effects compared to the predictions from several Monte Carlo programs. Chapter 6 discusses the final results and the comparison with theoretical expectations. Finally, Chapter 7 is devoted to the conclusions.