Master thesis defense by Christian Bierlich – University of Copenhagen

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Master thesis defense by Christian Bierlich

Limits on triple gauge boson couplings. Limits on the TGCs of the WWZ vertex using 827.8 inverse femtobarns of data, recorded with the ATLAS detector at the LHC at a center-of-mass energy of 7 TeV.

The Standard Model of Particle Physics is currently being put through a thorough test at the Large Hadron Collider, where protons are being smashed together at unprecedented energies to unveil the laws regarding the most minuscule constituents of matter. In this study the self-couplings of the electroweak gauge bosons (TGCs) introduced to preserve local SU(2)_L x U(1)_Y symmetry is estimated using data from the ATLAS detector.
This study looks specifically at the TGCs of the WWZ vertex, which in the Standard Model numbers to two, with values fixed by the Higgs mechanism. By including an extra TGC, the TGC estimation provides a model independent search for New Physics, by determining the deviation from the gauge structure of the Standard Model.
The TGC estimation procedure is evaluated through a Monte Carlo study. It is concluded that a procedure based on Matrix Element Reweighting, providing confidence intervals using a Neyman Construction is the most suitable for estimating TGCs. The estimation using these techniques is performed using 2011 ATLAS data, and results compatible with the Standard Model are reported.