| abstract |
This paper first gives an overview of the field of high energy particle physics (HEP). An
outline of the Standard Model of Elementary Particles (SM) is followed by a short introduction
to particle accelerators and colliders. We then present some important information about the
facility used in this work: the Large Hadron Collider and the ATLAS detector at CERN in
Switzerland. We then describe anomalous quartic gauge couplings (AQGC's), which are used to
investigate physics beyond the Standard Model in this paper. It then presents the statistical
methods used to conduct experiments and make discoveries in HEP, as well as the probabilistic
simulation technique used to compare theory to experiment.
Next, the original research is presented. First, we find the cross section for the WWγ
decay mode, a measure of how likely a given particle collision is to produce these three particles
together. The cross section was found to be 0.2655 ± 0.00098 picobarns at leading order, and
0.34864 ± 0.0022 picobarns with the next-to-leading order correction. A calculation of the
acceptance, the amount of signal that makes it into the final dataset, is conducted using an
established Monte Carlo simulation program, MadGraph5, along with code written specifically
for this project, run using another commonly used software, Rivet. Using the truth information
produced by the software for simulated signal events, we calculate how much of the signal is
accidentally thrown away by layers of selection cuts which are intended to cut out likely
background events. We find that roughly 15% (0.1496 ± 0.0000058 (stat) ± 0.00179 (sys)) of the
signal remains at the end of the selection cuts. This information will be used to make the results
reproducible by an analysis that does not utilize the same selection cuts or detector.
Finally, an investigation of beyond-SM physics is performed using the Eboli Model with
MadGraph5. The Eboli model contains 18 parameters that would change the strength of
AQGC's. We simulate the results of experiments in which these anomalous, beyond-SM
couplings exist using only one parameter, labeled T1. We simulate the cross section for the
process at several different strengths and use the expected sensitivity of our experimental data to
set a 95% confidence limit on the possible strength of the model parameters. The limit is found
to be 16.7 TeV-4. The limit is contingent upon confirmation that that the experimental cross
section for the WWγ decay mode analysis (still forthcoming) will agree with the SM. This
investigation can be used to inform new theories of beyond-SM physics and acts as an outline of
the process for setting a limit on each of the 14 parameters of the Eboli Model to which the
WWγ analysis is sensitive. That study will be published with the official discovery of the WWγ
decay mode by Professor Abbott's research group at the University of Oklahoma, within the
ATLAS Collaboration, when that work is completed.
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