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W boson helicity measurement in tt̄ di-electron channel with the CMS detector at the LHC and the CMS outer tracker upgrade for the HL-LHC

This thesis presents a measurement of the W boson helicity fractions in the tt̄ di-electron final state. The top pair events are produced in proton-proton collisions at a center-of-mass energy of 8 TeV, collected by the CMS experiment at the Large Hadron Collider (LHC), corresponding to an integrate...

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Detalles Bibliográficos
Autor principal: Behnamian, Hadi
Lenguaje:eng
Publicado: 2018
Materias:
Acceso en línea:http://cds.cern.ch/record/2319267
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author Behnamian, Hadi
author_facet Behnamian, Hadi
author_sort Behnamian, Hadi
collection CERN
description This thesis presents a measurement of the W boson helicity fractions in the tt̄ di-electron final state. The top pair events are produced in proton-proton collisions at a center-of-mass energy of 8 TeV, collected by the CMS experiment at the Large Hadron Collider (LHC), corresponding to an integrated luminosity of 19.7 fb −1 . Only events with two energetic opposite-sign electrons, at least two b-tagged jets and large missing transverse energy in the final state, are considered as di-electron tt̄ signal. The tt̄ event is fully reconstructed using the Analytical Matrix Weighting Technique (AMWT). The helicity fractions of the W boson are estimated from the cos θl∗ distribution using an event-by-event re-weighting technique. Within the quoted statistic and systematic uncertainties, the results are in good agreement with the Standard Model prediction at the 95% confidence level. The results are also consistent with other W boson polarization measurements in the CMS and the ATLAS experiments. While the W boson helicity fraction measurements are the main topic of this thesis, some important features of new silicon strip sensors for the CMS outer tracker upgrade are also investigated in this study.
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institution Organización Europea para la Investigación Nuclear
language eng
publishDate 2018
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spelling cern-23192672019-09-30T06:29:59Zhttp://cds.cern.ch/record/2319267engBehnamian, HadiW boson helicity measurement in tt̄ di-electron channel with the CMS detector at the LHC and the CMS outer tracker upgrade for the HL-LHCParticle Physics - ExperimentDetectors and Experimental TechniquesThis thesis presents a measurement of the W boson helicity fractions in the tt̄ di-electron final state. The top pair events are produced in proton-proton collisions at a center-of-mass energy of 8 TeV, collected by the CMS experiment at the Large Hadron Collider (LHC), corresponding to an integrated luminosity of 19.7 fb −1 . Only events with two energetic opposite-sign electrons, at least two b-tagged jets and large missing transverse energy in the final state, are considered as di-electron tt̄ signal. The tt̄ event is fully reconstructed using the Analytical Matrix Weighting Technique (AMWT). The helicity fractions of the W boson are estimated from the cos θl∗ distribution using an event-by-event re-weighting technique. Within the quoted statistic and systematic uncertainties, the results are in good agreement with the Standard Model prediction at the 95% confidence level. The results are also consistent with other W boson polarization measurements in the CMS and the ATLAS experiments. While the W boson helicity fraction measurements are the main topic of this thesis, some important features of new silicon strip sensors for the CMS outer tracker upgrade are also investigated in this study.CERN-THESIS-2016-375oai:cds.cern.ch:23192672018-05-22T11:10:56Z
spellingShingle Particle Physics - Experiment
Detectors and Experimental Techniques
Behnamian, Hadi
W boson helicity measurement in tt̄ di-electron channel with the CMS detector at the LHC and the CMS outer tracker upgrade for the HL-LHC
title W boson helicity measurement in tt̄ di-electron channel with the CMS detector at the LHC and the CMS outer tracker upgrade for the HL-LHC
title_full W boson helicity measurement in tt̄ di-electron channel with the CMS detector at the LHC and the CMS outer tracker upgrade for the HL-LHC
title_fullStr W boson helicity measurement in tt̄ di-electron channel with the CMS detector at the LHC and the CMS outer tracker upgrade for the HL-LHC
title_full_unstemmed W boson helicity measurement in tt̄ di-electron channel with the CMS detector at the LHC and the CMS outer tracker upgrade for the HL-LHC
title_short W boson helicity measurement in tt̄ di-electron channel with the CMS detector at the LHC and the CMS outer tracker upgrade for the HL-LHC
title_sort w boson helicity measurement in tt̄ di-electron channel with the cms detector at the lhc and the cms outer tracker upgrade for the hl-lhc
topic Particle Physics - Experiment
Detectors and Experimental Techniques
url http://cds.cern.ch/record/2319267
work_keys_str_mv AT behnamianhadi wbosonhelicitymeasurementinttdielectronchannelwiththecmsdetectoratthelhcandthecmsoutertrackerupgradeforthehllhc