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Title: Searches for non-resonant new physics in the high energy dielectron spectrum with ATLAS at the LHC
Author: Duguid, Liam
ISNI:       0000 0004 8497 9219
Awarding Body: Royal Holloway, University of London
Current Institution: Royal Holloway, University of London
Date of Award: 2014
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Presented is a search in the high mass dielectron spectrum for beyond the Standard Modelphysics exhibiting a non resonant behaviour. New physics processes such as four fermioncontact interactions and the ADD model with large extra dimensions, are searched forwith the ATLAS detector using proton-proton collisions from the Large Hadron Colliderat CERN. Results from two data sets are presented, the main results presented come froma data set with √s = 8 TeV and an integrated luminosity of 20.3 fb −1, these results arecompared to a data set with √s = 7 TeV and an integrated luminosity of 4.9 fb −1 completedprior. The main analysis was a search in the dielectron invariant mass distribution as wellas the angular variable cos θ∗, while the 7 TeV analysis searched in the dielectron invariantmass. No significant signal is found in either data set and so lower limits are set on the scaleof new physics for several formalisms of each model. For the 7 TeV analysis limits on thescale of new contact interactions (Λ) are set for the bench mark formalism of LL contactinteractions of Λ > 12.7 TeV and Λ > 9.63 TeV for the model for constructive and destructive interference with the Drell-Yan background respectively. In the same analysis limitsare set on the ADD model scale of new physics (MS) of MS > 3.0 TeV on the benchmarkformalism GRW.The 8 TeV analysis sets higher limits on the LL formalism of Λ > 21.55 TeV and Λ> 19.61 TeV for constructive and destructive interference. Limits are also set on otherformalisms with the highest limits set on the LR formalism of Λ > 26.25 TeV and Λ >23.77 TeV for constructive and destructive interference. Limits are set on the ADD GRWformalism of Ms > 4.79 TeV with limits on other formalisms also presented. At the timeof writing these are the highest public limits set on either theoretical models.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available