Measurements of fiducial differential cross sections for Higgs boson production in the diphoton decay channel at $\sqrt{s}=8$ TeV with ATLAS

In this thesis, measurements of fiducial differential cross sections are presented for Higgs boson production in proton-proton collisions at a center-of-mass energy of √s = 8 TeV. The analysis is performed in the H → γγ decay channel using 20.3 fb−1 of data recorded by the ATLAS experiment at the CERN Large Hadron Collider. The signal is extracted using a fit to the diphoton invariant mass spectrum, then the signal yields are corrected for the effects of detector inefficiency and resolution. Differential cross sections are presented as a function of variables related to the charged particles and the jet activity produced in the Higgs boson events. The observables considered are derived from the N -jettiness inclusive event-shape and build from track and jet information. These observables are sensitive to the distribution of the radiation in the event. Combining jet transverse momentum and jet rapidity information the variables $\tau_1$ and $\sum_i \tau_i$ are defined. These observables can be used as jet vetoes and their cross sections are theoretically well-controlled. The observed spectra are statistically limited but broadly in line with the theoretical expectations.