Measurement of the transverse momentum spectrum of $W$ bosons produced at $\sqrt{s}$ = 7 TeV using the ATLAS detector

W boson production at the Large Hadron Collider provides a fertile ground for testing predictions of the Standard Model. This thesis presents a measurement of the transverse momentum spectrum of W bosons produced via proton-proton collisions at p s = 7 TeV using the ATLAS detector. The results are found to be in good agreement with predictions made by Pythia Monte Carlo tuned to match the W and Z transverse momentum spectra observed in proton-antiproton collisions at p s = 1:96 TeV at the Tevatron. 125k W ! and 105k W ! e candidates were selected from data recorded in late 2010, totaling 30 pb1 in the muon channel and 33 pb1 in the electron channel. Background subtraction was performed using data driven techniques to estimate the background from multijet events, and Monte Carlo to estimate the background from W ! , Z ! ``, and top backgrounds. A data driven approach was used to estimate the calorimeter response to hadronic activity from the recoil of the W boson. Z ! `` (` = e; ) decays were selected in data, and deviations between the leptonic and hadronic transverse momenta were used to correct W signal Monte Carlo. The corrected response matrix was used to unfold the observed W transverse momentum spectrum to the truth level using an iterative technique called Bayesian unfolding. The unfolded spectrum was then corrected for selection efficiency and normalized to produce a shape suitable for tuning Monte Carlos.