A Monte Carlo simulation is performed of Higgs decays in the H → ZZ → 4l channel at ATLAS. Decay parameters are varied in order to model Higgs decays of differing CP states. A full analysis is performed, including trigger and background studies. Using various angular distributions as observables it is found that ATLAS should be able to exclude an anomalous CP odd coupling at 50 fb−1 and an anomalous CP even coupling at 100 fb−1. The CP violating case studied could not be excluded. / Graduate

LHC proton-proton collisions at a centre of mass energy of $\sqrt{s} = 7 TeV were observed in 2011. From a 1.68 fb$^{-1}$ sample of the data collected using the ATLAS detector, electron-positron pairs originating from the Drell-Yan process were selected using a cut based analysis. After the selection process, an estimate of the background was determined followed by the selection efficiency, detector resolution, reconstruction efficiency, and kinematic acceptance. Using these, the Drell-Yan differential cross section was calculated as a function of invariant mass between 26 and 66 GeV/c$^2$. This measurement has a precision between 12.4\% and 8.01\% from the lower invariant mass bins to the higher ones. The Drell-Yan cross section in proton-proton collisions depends on empirical quantities known as parton distribution functions which parametrize the structure of the proton. The measurement outlined in this thesis observes a region in parton distribution function phase space previously untouched by experiments. / Graduate

Quarks and leptons are assumed to be fundamental particles in the Standard Model of particle physics. The Large Hadron Collider provided 7 TeV proton-proton collisions in 2010. These collisions permit the search for quark substructure at a smaller length scale than was previously possible. This thesis is an investigation of the angular distribution of high dijet mass events in 36 pb^{−1} of data recorded by the ATLAS detector. Further contributions to technical aspects of the analysis are described in the appendices. This analysis excludes quark substructure at Λ < 5.3 TeV, corresponding to 3.7 × 10^{−5} fm, at 95% confidence level. / Graduate / 0798 / frank@uvic.ca

Using a measure of the jet energy resolution that relies on momentum balance in direct photon events, a correction to the modelled detector resolution is developed. The correction is produced by iteratively unfolding the model from the measured data. Jets in the model are then smeared using this correction, and the result is compared to the data using a χ2 test. This method is shown to be effective at improving the agreement between the data and the model, even when the model initially shows poor agreement to the data. / Graduate / 0798 / bmoir@ualberta.net

A search for diphoton events with large missing transverse energy is conducted using 3.1 pb^{-1} of integrated luminosity of proton-proton collisions at center of mass energy \sqrt{s}=7 TeV. The data were collected with the ATLAS detector at the CERN Large Hadron Collider during the period from March 30, 2010 until August 30, 2010. No excess of such events is observed above the Standard Model background prediction. This result is interpreted in the context of a gravity mediated One Universal Extra Dimension model with \Lambda R=20, N=6 and M_{D}=5 TeV, where \Lambda is the cutoff scale, N is the number of large extra dimensions and M_{D} is the Planck scale in the higher dimensional theory. The compactification radius of the Universal Extra Dimension, R, is excluded for values of 1/R < 728 GeV at 95\% CL, providing the most stringent limit on this model at the time of publication.

A search for diphoton events with large missing transverse energy is conducted using 3.1 pb^{-1} of integrated luminosity of proton-proton collisions at center of mass energy \sqrt{s}=7 TeV. The data were collected with the ATLAS detector at the CERN Large Hadron Collider during the period from March 30, 2010 until August 30, 2010. No excess of such events is observed above the Standard Model background prediction. This result is interpreted in the context of a gravity mediated One Universal Extra Dimension model with \Lambda R=20, N=6 and M_{D}=5 TeV, where \Lambda is the cutoff scale, N is the number of large extra dimensions and M_{D} is the Planck scale in the higher dimensional theory. The compactification radius of the Universal Extra Dimension, R, is excluded for values of 1/R < 728 GeV at 95\% CL, providing the most stringent limit on this model at the time of publication.

Zugl.: Siegen, Univ., Diss., 2008

Thesis (M.A.)--Carleton University, 1992. / Also available in electronic format on the Internet.

Universiẗat, Diss., 2000--Heidelberg.

Universiẗat, Diss., 2002--München.