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Title: High jet multiplicity physics at the Large Hadron Collider
Author: Crispin Ortuzar, Mireia
ISNI:       0000 0004 5365 9511
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2015
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The Large Hadron Collider at CERN completed its first data-taking phase in 2013, after three years of remarkable performance. The high-energy proton-proton collisions recorded by the ATLAS experiment provide a gateway to the world of subatomic particles. This thesis presents two analyses of the full 8 TeV dataset taken by ATLAS, inspired by two of the major physics goals of the experiment. The first analysis is a search for new phenomena that could explain the nature of Dark Matter and solve the hierarchy problem. In particular, the search is optimised to look for heavy supersymmetric particles decaying to large numbers (7 to ≥10) of jets. The events are further classified according to the number of jets identified as originating from a b quark. No evidence is found for physics beyond the Standard Model, so the results are interpreted in terms of exclusion limits on various simplified supersymmetry-inspired models where gluinos are pair produced, as well as a mSUGRA/CMSSM model. The main background to the search is due to multi-jet production via the strong force. This motivates the second analysis presented in this thesis, which is a measurement of the cross section of four-jet events. The measurement is performed differentially in a series of variables which describe the kinematics and spatial configuration of the events. The results are compared to existing theoretical predictions.
Supervisor: Barr, Alan J. Sponsor: Caja Madrid Foundation ; British Spanish Society ; Balliol College ; Telefonica S.A.
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Particle physics ; Physics ; supersymmetry ; jets