This thesis presents details of the search for the Standard Model Higgs boson, in the low mass region (100 ≤ MH < 150 GeV), with the ATLAS detector at CERN. In this range, a Higgs boson may be produced in association with a W or Z-boson and decay predominantly to two b-quarks (H → b¯b). Specifically events having large Higgs boson transverse momentum (pT > 200 GeV) and large recoiling W- boson transverse momentum (pT > 200 GeV) are considered as a means to reduce the contribution from background processes. In this high pT (boosted) regime, novel jet-substructure techniques are applied to the reconstructed jets resulting from the Higgs boson decay. In order to use these jet-substructure techniques, b-tagging efficiency scale factors in the jet-substructure regime have also been derived for the first time. Details of their derivation are presented for many b- tagging algorithms, with 14.3 fb¯¹ of ATLAS proton-proton collision data in 2012 at √s = 8 TeV. These, and their associated systematic uncertainties, are then applied to the Higgs boson search. No significant measurement of Higgs boson production was made, based on 20.4 fb¯¹ of ATLAS proton-proton collision data in 2012 at √s = 8 TeV. For a Higgs boson mass of 125 GeV, an exclusion limit of 6.12 x σSM was found at the 95% confidence level, and a signal strength of 0:93 ± 2:63 was measured, consistent with both background-only and signal (Standard Model Higgs boson) plus background hypotheses.

Class of 2015 Abstract / Objectives: The aim of this study was to develop a computational process capable of hypothesizing potential chemotherapeutic agents for the treatment of skin cutaneous melanoma given an annotated chemotherapy molecular target database and patient-specific genetic tumor profiles. Methods: Aberrational profiles for a total of 246 melanoma patients indexed by the Cancer Genome Atlas (TCGA) for whom complete somatic mutational, mRNA expression, and protein expression data was available were queried against an annotated targeted therapy database using Visual Basic for Applications and Python in conjunction with Microsoft Excel. Identities of positively and negatively associated therapy-profile matches were collected and ranked. Results: Subjects included in the analysis were predominantly Caucasian (93%), non-Hispanic (95.9%), female (59%), and characterized as having stage III clinical disease (37.4%). The most frequently occurring positive and negative therapy associations were determined to be 17-AAG (tanespimycin; 42.3%) and sorafenib (41.9%), respectively. Mean total therapy hypotheses per patient did not differ significantly with regard to either positive or negative associations (p=0.1951 and 0.4739 by one-way ANOVA, respectively) when stratified by clinical melanoma stage. Conclusions: The developed process does not appear to offer discernably different therapy hypotheses amongst clinical stages of cutaneous melanoma based upon genetic data alone. The therapy-matching algorithm may be useful in quickly retrieving potential therapy hypotheses based upon the genetic characteristics of one or many subjects specified by the user.

Le gisement aurifère de Tamlalt-Menhouhou se situe sur la bordure sud de la boutonnière paléozoïque de Tamlalt (Haut-Atlas oriental), jouxtant la limite entre la chaîne du Haut-Atlas et la chaîne de l'Anti-Atlas. Les minéralisations sont encaissées dans des formations volcano-sédimentaires de l'Ediacarien (âge U/Pb : 569 ± 8 Ma). Deux minéralisations aurifères ont pu être identifiées : (i) une minéralisation aurifère primaire de type "Iron Oxide Copper Gold deposit" (IOCG) associée à un altération sodique (± calcique) caractérisée par un enrichissement en Au, Cu, Fe, Co, Ni, Mo, As, Sb, ± Bi, et (ii) une minéralisation aurifère secondaire de type "Shear zone related gold deposit" associée aux altérations argilleuses et phylliteuses localisées le long des décro-chevauchements. L'étude détaillée à la microsonde ionique effectuée sur les zircons hydrothermaux génétiquement associés au phénomène d'albitisation permet d'obtenir un âge Ordovicien supérieur (449 ± 8 Ma) pour la minéralisation aurifère primaire. Cet âge est confirmé par la datation 40Ar/39Ar sur deux mono-grains de muscovites et souligne le potentiel des zircons à enregistrer des évènements hydrothermaux, et leur intérêt en métallogénie. La minéralisation aurifère secondaire est datée au Stéphano-autunien (293 ± 7 Ma) par géochronologie 40Ar/39Ar sur des phengites associées à l'altération argilleuse et phylliteuse et aux veines de quartz aurifères. Cet âge souligne l'importance de cette orogenèse pour la remobilisation de pré-concentrations métallifères. / The Tamlalt-Menhouhou gold deposit is located on the southern edge of the Neoprotérozoic-Palaeozoic Tamlalt inlier (Eastern High-Atlas), just north of the limit between the High-Atlas belt and the Anti-Atlas belt. Mineralizations are enclosed in Ediacaran volcano-sedimentary formations (U/Pb age: 569 ± 8 Ma). Two different gold mineralizations were identified: (i) a primary gold mineralization of the type “Iron Oxide Copper Gold deposit” (IOCG) characterized by a strong sodic (± calcic) alteration and (ii) a secondary gold mineralization corresponding to a “Shear zone related gold deposit” and related to a strong argillic and phyllic alteration localized along the shear faults. A detailed ion microprobe study of hydrothermal zircons genetically associated with albitization provide a Late Ordovician age (449 ± 8 Ma) for primary gold mineralization. This age is confirmed by 40Ar/39Ar dating of two muscovite mono-grains, and underscores the potential of zircons to record hydrothermal events, and the interest of these phases for metallogeny. A Late Variscan age (293 ± 7 Ma) is defined by 40Ar/39Ar analysis of phengites from the phyllic alteration synchronous with auriferous quartz vein development, and which is assumed to represent the age of gold mineralization. This age demonstrates the consequences of the Variscan orogeny for the re-mobilization of metalliferous pre-concentrations.

In its first three years of operation, the Large Hadron Collider at CERN has already proved its worth as a discovery machine and reinvigorated the prospects for discovering new dynamics beyond the Standard Model. This thesis presents a range of experimental methods devised for discovery of supersymmetry, one of the most important extensions of the Standard Model being tested at the LHC. The first chapter discusses the concepts behind a set of transverse mass-bound variables, and explores connections between these variables and others in the literature. Not only are these variables important tools for mass measurement, should sparticles be seen at the LHC, they are also critical components of experimental searches. Accordingly, their performance has been compared in both mass measurement and search contexts, and the results are reported here. This is followed by the details of a search for hadronically-decaying squarks and gluinos, carried out on 4.7 fb−1 of data collected at 7 TeV in 2011 by the ATLAS detector. The search strategy is described, focusing on the implementation of a background estimation method using photon events to determine the background contamination due to invisible Z boson decays. The results of the search are then presented. Stringent limits are set on the production of squarks and gluinos in a variety of model scenarios.

This thesis presents measurements of the the spin correlation strength in top anti-top quark pair production at the LHC using the ATLAS detector. The data used corresponds to 4.6 fb−1 of integrated luminosity taken during 2011 at the LHC at a center of mass energy of 7 TeV. The spin correlation is studied utilising different observables with different sensitivities to the production mechanism, in particular to gluon-gluon fusion in the like or unlike helicity state, quark anti- quark annihilation in the unlike helicity state, or a combination of the three. In addition cuts are made on the invariant mass of the ttbar system to enhance or suppress contributions from different initial state production mechanisms. The analysis presented is a precision test of both ttbar production and decay in the SM. These measurements are compared to the most current theoretical predictions. No deviation from the SM expectation was observed. In a subset of the data, corresponding to an integrated luminosity of 2.1 fb−1, the hypothesis of zero spin correlation is excluded at 5.1 standard deviations.

3D silicon pixel detectors are a novel technology where the electrodes penetrate the sili- con bulk perpendicularly to the wafer surface. As a consequence the collection distance is decoupled from the wafer thickness resulting in a radiation hard pixel detector by design. Between 2010 and 2012, 3D silicon pixel detectors have undergone an intensive programme of beam test experiments. As a result, 3D silicon has successfully qualified for the ATLAS upgrade project, the Insertable B-Layer (IBL), which will be installed in the long-shutdown in 2013-14. This thesis presents selected results from these beam test studies with 3D sensors bonded to both current ATLAS readout cards (FE-I3) and newly developed readout cards for the IBL (FE-I4). 3D devices were studied using 4 GeV positrons at DESY and 120 GeV pions at the SPS at CERN. Measurements presented include tracking efficiency (of the whole sensor, the pixel and the area around the electrodes), studies of the active edge pixels of SINTEF devices and cluster size distributions as a function of incident angle for IBL 3D design sensors. A simulation of 3D silicon sensors in an antiproton beam test for the AEgIS experiment, with comparison to experimental results and a previous simulation, are also presented.

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Data collected at the LHC are analyzed by the ATLAS collaboration for evidence of dark matter. In this thesis, a fast simulation of the ATLAS detector response using the Delphes software is assessed for dark matter models with a leptonically decaying Z boson and a pair of dark matter particles in the final state. Limits for the Two Higgs Doublet plus pseudoscalar dark matter model are obtained using simplified systematics, and found to be nearly indistinguishable to limits obtained using the more complex standard ATLAS analysis. / Graduate

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