Conclusions

Abstract

This thesis presented fiducial and differential cross section measurements of the Higgs boson at $\sqrt{s}=8$ TeV with the ATLAS detector, and fiducial and total cross section measurements of WZ diboson production at $\sqrt{s}=13$ TeV. The electron likelihood method of identification, first introduced in Run 1 and adapted for use in Run 2, is described in detail. Electron efficiency measurements of identification criteria are described as well, featuring methods developed in Run 1 and employed during Run 2 data taking.

This thesis presented fiducial and differential cross section measurements of the Higgs boson at $\sqrt{s}=8$ TeV with the ATLAS detector, and fiducial and total cross section measurements of WZ diboson production at $\sqrt{s}=13$ TeV. The electron likelihood method of identification, first introduced in Run 1 and adapted for use in Run 2, is described in detail. Electron efficiency measurements of identification criteria are described as well, featuring methods developed in Run 1 and employed during Run 2 data taking.

The Higgs fiducial cross section and decay to four leptons (e or $\mu$) at 8 TeV was measured to be $\sigma _\text {fid}=2.11$ $^{+0.53}_{-0.47}$ (stat) $\pm 0.08$ (syst) fb, and can be compared to the theoretical prediction [1] of a Higgs with mass 125.4 GeV of $1.30\pm 0.13$ fb. Unfolded differential distributions of kinematic observables show no statistically significant deviation from the SM predictions according to a number of state-of-the-art generators.

The $WZ$ fiducial cross section and decay to a leptonic channel in 13 TeV $p$–$p$ collisions is measured to be $\sigma _\text {fid}=63.2\pm 3.2$ (stat) $\pm 2.6$ (syst) $\pm 1.5$ (lumi) fb. When extrapolated to the total phase space, the total cross section is $\sigma _\text {tot}=50.6\pm 2.6$ (stat) $\pm 2.0$ (syst) $\pm 0.9$ (syst) $\pm 1.2$ (lumi) pb, in good agreement with the recent NNLO calculation [2] predicting $48.2^{+1.1}_{-1.0}$ pb.