Study of gamma + jets data with the CMS detector in pp collisions at sqrt(s) = 8 TeV

The characterization of the production process of prompt photons γ in association with hadronic jets (γ + jets process) at the Large Hadron Collider (LHC), is one of the goals in physics analyses at the Compact Muon Solenoid (CMS) experiment. This channel provides a way of directly probing the hard scattering process and it is directly sensitive to the gluonic content of the proton. This process is also the starting point for the study of many Standard Model signatures, and constitutes a background for important searches, such as H->γγ, or SUSY and extra-dimensions with energetic photons in the final state. This thesis presents the measurement of the γ + jets differential cross section production as a function of the photon transverse momentum pT in the high pT kinematic region, in proton-proton collisions at a center-of-mass energy of sqrt(s) = 8 TeV collected by the CMS detector with an integrated luminosity equal to L = (19.7 ± 0.5) fb(-1). A series of selection cuts have been applied in order to identify the γ + jets process with respect to the background. The selection efficiencies have been extracted with a data-driven method (Tag & Probe) and have been used to correct the efficiencies extracted from the Monte Carlo simulations. To perform a precise set of measurements in the γ + jets final state, a background extraction with a data-driven approach has been applied by using a data-driven modeling for signal and background. The calculation of the differential cross section has then been performed after a bin-by-bin correction of the detector effects on the selected photons. A detailed treatment of the systematic uncertainties affecting the process has also been performed.