Measurement of the $W \rightarrow e\nu$ and $Z/\gamma^* \rightarrow ee$ Production Cross-Sections in Proton-Proton Collisions at $\sqrt{s}=7$ TeV with the ATLAS Experiment

In this thesis measurements of the inclusive $W$ and $Z/\gamma^*$ boson production cross-sections in proton-proton collisions at a centre-of-mass energy of $7$ TeV are presented. The measurements are performed using the decays of $W \rightarrow e\nu$ and $Z/\gamma^* \rightarrow ee$. They are based on a dataset corresponding to an integrated luminosity of $36$ $\mathrm{pb^{-1}}$ recorded by the ATLAS experiment in 2010. The $W$ boson cross-section is measured differentially in the electron pseudorapidity and separately for positive and negative charge. The $Z/\gamma^*$ boson production cross-section is measured differentially as a function of the boson rapidity. In addition, the cross-sections are integrated over the fiducial kinematic range and extrapolated to the full range. Ratios of the integrated cross-sections are reported and the $W/Z$ cross-section ratio is used to extract the total width of the $W$ boson. The measured total cross-sections are $\sigma_{\rm tot} \times BR(W \rightarrow e\nu) = 10.26 \pm 0.03 \mathrm{(stat)} \pm 0.19 \mathrm{(syst)} \pm 0.35 \mathrm{(lumi)} \pm 0.16 \mathrm{(acc)}$ nb and $\sigma_{\rm tot} \times BR(Z/\gamma^* \rightarrow ee) = 0.952 \pm 0.010 \mathrm{(stat)} \pm 0.026 \mathrm{(syst)} \pm 0.032 \mathrm{(lumi)} \pm 0.019 \mathrm{(acc)}$ nb. Theoretical predictions based on calculations at next-to-next-to-leading order in the strong coupling constant are found to agree with the measurements. The predictions are sensitive to the parton distribution functions (PDFs). Therefore, the measurements can be used to constrain those PDFs in order to improve the predictions for other processes probed at the Large Hadron Collider (LHC).