Global ETD Search

1	Search for Vector-Like Quarks using Trilepton and Same-Sign Dilepton Events in 20.3 fb⁻¹ of Proton-Proton Collisions at √S = 8 TeV with the ATLAS Detector O'Grady, Fionnbarr Timothy January 2015 (has links) A search is presented for vector-like quarks using 20.3 fb⁻¹ of proton-proton collisions at a center-of-mass energy of √S = 8 TeV collected with the ATLAS detector in 2012 at the CERN Large Hadron Collider. Vector-like quarks are predicted to exist in many theories beyond the Standard Model of particle physics that attempt to resolve the hierarchy problem. Events are selected containing jets including at least one b-jet, sizable missing transverse momentum, large scalar sum of the jet and lepton transverse momenta, and either three leptons or two leptons with the same electric charge. Standard Model processes rarely produce this final state and production of vector-like quarks would lead to an enhanced rate of such events. The data are interpreted in the context of a variety of models including pair production of vector-like quarks T and B, which have the same electric charge as the corresponding Standard Model quarks and can appear in either SU(2) weak isospin singlets, doublets or triplets. In addition single and pair production of the vector-like quark T₅/₃ which appears in an SU(2) weak isospin doublet or triplet and has electric charge 5/3, is considered. A moderate excess of data above the SM background expectation is observed with a significance of less than two standard deviations. The data are used to set limits at 95% Confidence Level (CL) on the new heavy quark mass for the various VLQ models considered using the CL_S method. The vector-like quarks T and B in the singlet model are excluded at 95% CL below a mass of 0.59 TeV and 0.62 TeV respectively. The T₅/₃ is excluded at 95% CL below a mass of 0.74 TeV when only pair production is considered and below 0.75 TeV when both pair and single production are considered. dilepton Fionnbarr O'Grady vector-like VLQ ATLAS Physics
2	A Preliminary Investigation of an Online Version of the Valued Living Questionnaire Chamberlain, Amanda B 01 September 2020 (has links) Acceptance and commitment therapy (ACT) is an empirically supported cognitive behavioral therapy. The ACT model is designed around a set of six core processes utilized to increase psychological flexibility. Engagement with values, one of the six core processes, is associated with several indicators of well-being. However, recent reviews of ACT values measures from experts in the field raised concerns that current instruments do not adequately assess the values process. The current study examined the structure and psychometric properties of a new values measure, titled the Valued Living Questionnaire—Online version (VLQ-O), that was developed from considerations raised in these reviews. The results of an EFA indicated that the VLQ-O produced a three-factor structure comprised of Values Flexibility, Values Inflexibility, and Values Obligations. The Activity and Preferred Activity scores did not load consistently onto any discernable factor. The subscales of the VLQ-O produced poor internal consistency. The scores for Activity and Values Flexibility subscales correlated positively with measures of well-being and negatively with measures of psychological distress. Additionally, these subscales were significantly positively related to MPFI Flexibility and VQ Progress and well as negatively related to MPFI Inflexibility and VQ Obstruction. Values Inflexibility and Values Obligation correlated positively with measures of psychological distress and negatively with measures of well-being. The Values Obligation subscale did not correlate with social desirability. Multiple subscales of the VLQ-O demonstrated significant correlations with multiple subscales of the BFI. Additionally, the VLQ-O established predictive validity for measures of psychological distress and well-being. Further, it established improvements in predictive validity for flourishing and psychological distress when compared to the Valuing Questionnaire (VQ). Overall, the findings from this study provide some supportive preliminary evidence for the validity of the VLQ-O. Acceptance and Commitment Therapy ACT Valued Living Questionnaire Values VLQ
3	Le quark top comme sonde pour la recherche de nouvelle physique au LHC, avec le détecteur ATLAS / The top quark as a probe for searching new physics at the LHC using the ATLAS detector Kukla, Romain 17 June 2016 (has links) Les travaux présentés dans cette thèse ciblent la recherche de nouvelle physique au-delà du Modèle Standard dans le cadre des modèles composites, lesquels font intervenir des secteurs fortement couplés à l'échelle du TeV comprenant des particules exotiques. Leur existence peut être testée auprès du collisionneur proton-proton LHC situé au CERN, grâce au détecteur ATLAS. La production d'un quark lourd, comme le T5/3, prédit dans ces modèles, peut être déduite d'une section efficace anormalement élevée d'une signature spécifique. Certains états finaux, comme celui étudié dans cette thèse impliquant 2 leptons de même signe, étant très rares, possèdent une excellente sensibilité. Les recherches des processus de création du T5/3 au LHC en utilisant les données d'ATLAS à 8 et 13 TeV sont présentées. Un léger excès a été observé à 8 TeV. Des résultats préliminaires de l'analyse à 13 TeV sont présentés et ne montrent pas d'excès. Les limites inférieures en masse sur cette particule hypothétique sont de 745 GeV à 8 TeV et de 990 GeV à 13 TeV. Les modèles composites prévoient aussi l'existence de bosons lourds comme par exemple un Z' topophile qui ne se couplerait qu'aux quarks top et dont la production en association d'une paire tt donnerait un état final similaire aux événements à 4 quarks top. Une étude phénoménologique sur le potentiel de découverte de ces processus exotiques (Z' et théorie effective) ou standard (tttt) à 13 et 14 TeV est effectuée et donne les luminosités minimales nécessaires pour pouvoir observer des déviations au Modèle Standard. Une étude instrumentale d'une nouvelle carte de déclenchement de niveau 1 du calorimètre électromagnétique est aussi décrite en prévision de la phase d'Upgrade du détecteur. / The work of this thesis focuses on the search for new physics beyond the Standard Model in the compositeness framework, which postulates strongly coupled sectors at the TeV-scale consisting of exotic particles. Their existence can be tested at the CERN proton-proton collider, the LHC, using the ATLAS detector. The production of an heavy quark, such as the T5/3 predicted in those models, can be inferred from an enhancement of the cross-section of a given signature. Some final states, such as the one studied in this thesis involving 2 same-sign leptons, are very rare and have an excellent sensitivity. Searches for T5/3 production at the LHC using 8 and 13 TeV ATLAS data are presented. A small excess is seen at 8 TeV. Preliminary results of the 13 TeV analysis are presented and do not show any excess. The inferior limits put on the T5/3 mass is 745 GeV at 8 TeV and 990 GeV at 13 TeV. Composite models include also heavy bosons such as top-philic Z' coupled only to the top quark whose production in association to a top quark pair gives a final state similar to those from 4 tops events. A phenomenological study on the discovery potential of those exotic (Z' and effective theory) or standard (tttt) processes at 13 and 14 TeV is done and gives the minimal luminosities needed to observe deviations from the Standard Model. An instrumental study for the conception of the new LTDB card, part of the electromagnetic calorimeter's level 1 trigger system is described in the context of the ATLAS upgrade program. LHC ATLAS Quark top Exotique Modèles composites T5/3 2 leptons de même signe BSM VLQ LHC ATLAS Top quark Exotic Compositeness T5/3 2 same-sign leptons BSM VLQ
4	Recherche de quarks vectoriels produits par l'échange de gluons lourds dans le cadre de modèles de Higgs composite avec le détecteur ATLAS Dallaire, Frédérick 04 1900 (has links) No description available. LHC ATLAS Higgs composite Problème de hiérarchie Quarks vectoriels VLQ Gluon lourd Production simple 8 TeV Composite Higgs Mass hierarchy problem Vector-like quarks Heavy gluon Single production
5	Exotic Decays of a Vector-liketop Partner at the LHC Skwarcan-Bidakowski, Alexander January 2019 (has links) An evaluation of how sensitive some ATLAS searches for new physics are to a new beyond standard model (BSM) vector-like quark (VLQ) and a pseudo Nambu-Goldstone boson (pNGB) scalar. This was done by simulating a signal containing these new particles and making a recast of it onto existing verified ATLAS searches for new physics at center-of-mass (CM) energy of 13 TeV (Run 2) at the Large Hadron Collider (LHC). Signals for recasting were tailored such that their final states would be appropriate in relation to each respective ATLAS search in order to use the same selection criteria as applied in the existing searches. The results are summarized in the form of significances (Z) for each masspoint of the new top-partner and S particle. Significances did not show any expectiation of excluding any masspoint in the examined mass range for the recasts at 95% CL. This suggests that a dedicated search for these particles in the considered masspoints would be required. Particle physics Vector-like quarks VLQ Composite Higgs model CHM Top-partner pseudo Nambu-Goldstone boson pNGB NGB ATLAS LHC CMS Significance Recast CheckMate CM MadGraph Pythia Delphes Detector Analysis Hierarchy Problem Exotic Decay QFT Quantum Field Theory fermions bosons Jets photons leptons 13 TeV Missing Transverse Energy momentum hypothetical selection criteria Standard model Signal background event Higgs Mechanism Simulation Confidence limit Other Physics Topics Annan fysik Accelerator Physics and Instrumentation Acceleratorfysik och instrumentering Subatomic Physics Subatomär fysik

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