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Title: A search for new physics in the γγ channel with the ATLAS experiment at √s = 7 TeV
Author: Waller, Peter
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2013
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In this thesis, the diphoton invariant mass distribution mγγ is measured using data collected with the ATLAS detector at the LHC during 2011. The inte- grated luminosity collected suitable for data analysis during this time was L = 4.9 fb^−1 ± 1.3%. The properties of the mγγ distribution are studied by observing the data in a control region 140 GeV < mγγ < 400 GeV. A statistical procedure is used to search the mγγ distribution for the presence of a statistically significant excess of events in a generalised manner. The p-value for this search is 0.734 ± 0.004, which is consistent with the null hypothesis. The 95% Bayesian limit on the cross-section times branching ratio of the Randall Sun- drum graviton decaying to diphotons σ × Br G → γγ in the data, along with the expected limit, is determined as a function of mass with a coupling param- eter of k/Mpl = 0.1. The exclusion limits are recast to other values of k/Mpl by scaling the cross-section limit according to its theoretical dependence of the cross-section on k/Mpl . The parameters of the Randall Sundrum model are bounded by the analysis with approximately mG > 1 TeV for k/Mpl = 0.01 and mG > 2 TeV for k/Mpl = 0.1.
Supervisor: Maxfield, S. J. M.; Hayward, H. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QC Physics