Analysis of top anti-top decays in the lepton plus jets channel at the ATLAS experiment

dc.creatorCimmarusti, Andrés
dc.date2008-08-07
dc.date2008-08-07T09:00:00Z
dc.date2008-08-07T09:00:00Z
dc.date2006-11-24
dc.date2008-08-07T09:00:00Z
dc.date.accessioned2022-11-16T23:53:19Z
dc.date.available2022-11-16T23:53:19Z
dc.identifierT016300005136/0
dc.identifierhttp://www.saber.ula.ve/handle/123456789/14687
dc.identifier.urihttps://repositorioslatinoamericanos.uchile.cl/handle/2250/5207971
dc.descriptionAnálisis del sismo del Táchira del 31 de mayo de 1994 y sus réplicas (Mata S., Sara M.) Resumen Particle physics includes all the experimental research aimed at advancing in the understanding of quarks (the components of protons and neutrons) and leptons (such as electrons), as well as their mutual interactions. The study of the properties of the top quark, the heaviest of the six known quarks, in particular its mass, is of uttermost importance as it may give clues on the origin of the mass di®erence between the particles and indicate the existence of physics beyond the Standard Model of particle physics. At the start of the Large Hadron Collider at Cern in 2007, the top quark will be produced with large statistics. The Atlas experiment will have the possibility to study its properties in great detail. The top quark is an unstable particle that decays almost instantaneously and exclusively into a b quark and a W boson, which in turn form jets of stable particles. The precision in the measurement of top quark properties will be limited by the knowledge of some of the detector performances, such as the precision to which the particle energies are measured, or the e±ciency with which we can identify some of these particles. The preparation of physics analyses requires the best knowledge of detectors and physics simulation. I have worked during my internship at the LPNHE Paris on the preparation of two physics analyses on simulated data. A first study has been performed, corresponding to the commisioning phase of the detector with the first data. It has been shown that in Atlas the top quark can be easily reconstructed, even using a very simple selection and without fulfilling requirements such as flavour tagging or jet energy reconstruction. A second analysis has been performed after the detector and the data were understood. The background due to jets misidentified in the detector as electrons has been studied and found to be negligible. The mass reconstruction performance has been studied for different selections of the final state of the top quark decay. The statistical uncertainty on it will become negligible after a few weeks of data taking compared to the uncertainties related to the jet energy reconstruction. These analyses are a first step for the LPNHE group in their development of physics analyses for the top quark mass measurement.
dc.descriptionUniversidad de Los Andes
dc.description1. Abstract
dc.description2. The Standard Model
dc.description2.1 Particle Organization
dc.description2.2 Unanswered questions
dc.description2.3 Top quark physics
dc.description2.3.1 Top quark production in colliders
dc.description2.3.2 Characteristics of tt events
dc.description2.3.3 Reducible backgrounds
dc.description3. The ATLAS experiment
dc.description3.1 The LHC at CERN
dc.description3.2 The ATLAS detector
dc.description3.2.1 Coordinate system
dc.description3.2.2 Tracking system or Inner Detector
dc.description3.2.3 Calorimetry
dc.description3.2.4 Muon spectrometer
dc.description3.2.5 Magnet system
dc.description3.2.6 Trigger system
dc.description3.3 Data flow
dc.description3.3.1 Physics generation
dc.description3.3.2 Detector response simulation
dc.description3.3.3 Event selection and reconstruction
dc.description3.4 Data sample
dc.description4. Particle identification
dc.description4.1 Jet reconstruction
dc.description4.1.1 Algorithm
dc.description4.1.2 Jet definition
dc.description4.1.3 Jet energy precalibration
dc.description4.2 Electron reconstruction
dc.description4.3 Muon reconstruction
dc.description4.4 Missing ET
dc.description5. Fighting against reducible background: electron / jet separation
dc.description5.1 Selection criteria
dc.description5.1.1 Trigger selection
dc.description5.1.2 Offline Analysis
dc.description5.2 Electron identification performance
dc.description5.3 Jet rejection
dc.description6. Top events selection without calibration and b-tagging
dc.description6.1 Selection of events
dc.description6.1.1 Preselection
dc.description6.1.2 Final selection
dc.description6.1.3 Selection of the light jets
dc.description6.2 Top mass measurement
dc.description7. Analysis using b-tagging information
dc.description7.1 Selection of events
dc.description7.1.1 Preselection
dc.description7.1.2 Final selection
dc.descriptionB.2.1. Localizaciones
dc.descriptionB.2.2. Eventos de Referencia
dc.descriptionB.2.3. Relocalizaciones
dc.description7.2 Hadronic W reconstruction
dc.description7.2.1 In situ jet energy calibration
dc.description7.2.2 W mass reconstruction
dc.description7.3 Top reconstruction
dc.description7.3.1 Choice of the b-jet associated to the hadronic W
dc.description7.3.2 Top mass measurement
dc.description7.3.3 Systematic errors
dc.description8. Conclusion
dc.description52
dc.descriptionCIENCIAS-0011
dc.descriptionFísico
dc.descriptionNivel monográfico
dc.format17193645
dc.formatapplication/pdf
dc.formattext/html
dc.languagees
dc.publisherSABER ULA
dc.rightsinfo:eu-repo/semantics/openAccess
dc.rightshttp://creativecommons.org/licenses/by-nc-sa/3.0/ve/
dc.subjectFísica
dc.subjectDepartamento de Física
dc.subjectFacultad de Ciencias.
dc.subjectInglés
dc.subjectNetwork
dc.subjectTesis
dc.titleHigh energy Latinamerican-European network fellowship
dc.titleAnalysis of top anti-top decays in the lepton plus jets channel at the ATLAS experiment
dc.typeinfo:eu-repo/semantics/bachelorThesis


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