Measurement Of Differential Cross Sections In The Ttbar L Jets Channel
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Measurement Of Differential Cross Sections In The Ttbar L Jets Channel
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Author :
language : en
Publisher:
Release Date : 2009
Measurement Of Differential Cross Sections In The Ttbar L Jets Channel written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with categories.
The analysis presented in this thesis focuses on kinematic distributions in the t{bar t} system and studies in detail selected differential cross sections of top quarks as well as the reconstructed t{bar t} pair, namely the top quark transverse momentum and the t{bar t} system mass. The structure of the thesis is organized as follows: first the Standard Model of the particle physics is briefly introduced in Chapter 1, with relevant aspects of electroweak and strong interactions discussed. The physics of the top quark and its properties are then outlined in Chapter 2, together with the motivation for measuring the transverse top quark momentum and other kinematic-related variables of the t{bar t} system. The concepts of present-day high energy physics collider experiments and the explicit example of Fermilab Tevatron collider and the D0 detector in Chapters 3 and 4 are followed by the description of basic detector-level objects, i.e. tracks, leptons and jets, in Chapter 5; their identification and calibration following in next chapter with the emphasis on the jet energy scale in Chapter 6 and jet identification at the D0. The analysis itself is outlined in Chapter 7 and is structured so that first the data and simulation samples and the basic preselection are described in Chapter 8 and 9, followed by the kinematic reconstruction part in Chapter 10. Chapter 11 on background normalization and Chapter 12 with raw reconstructed spectra results (at the detector-smeared level) are followed by the purity-based background subtraction method and examples of signal-level corrected spectra in Chapter 13. Next, the procedure of correcting measured spectra for detector effects (unfolding) is described in Chapters 14-15, including migration matrix studies, acceptance correction determination as well as the regularized unfolding procedure itself. Final differential cross sections are presented in Chapter 16 with the main results in Figures 16.19-16.20. Summary and discussion close the main analysis part in Chapter 17, supplemented by appendices on the wealthy of analysis control plots of the t{bar t} → l + jets channel, selected D0 event displays and finally the list of publications and references. Preliminary results of this analysis have been documented in D0 internal notes [UnfoldTop], [p17Top], [p14Top]; as well as presented at conferences [APS08], [APS05]. The author has also been a co-author of more than 135 D0 collaboration publications since 2005. The author has taken part in the jet energy scale calibration efforts performing final closure tests and deriving a correction to jet energy offset due to the suppression of the calorimeter signal. The author has also co-performed the [phi]-intercalibration of the hadronic calorimeter and co-supervised the electromagnetic [phi]-intercalibration; recently has also been involved in maintaining the jet identification efficiencies measurement as a JetID convener. During the years in Fermilab, many events have taken place in the course of the analysis in persuasion, including more than 170 shifts served for the D0 detector with or without the beam, 168 talks presented with mixed results and reactions; and tens of thousands of code lines in C (and sometimes perhaps even really C++) written while terabytes of data were processed, analyzed, and sometimes also lost. It has been a long but profoundly enriching chapter of my life.
Spin Correlations In Tt Events From Pp Collisions
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Author : Boris Lemmer
language : en
Publisher: Springer
Release Date : 2015-06-24
Spin Correlations In Tt Events From Pp Collisions written by Boris Lemmer and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015-06-24 with Science categories.
This thesis introduces readers to the Standard Model, the top quark and its properties, before explaining the concept of spin correlation measurement. The first measurement of top quark spin correlations at the LHC in the lepton+jets decay channel is presented. As the heaviest elementary particle, the top quark plays an essential role in the Standard Model of elementary particle physics. In the case of top quarks being produced in pairs at hadron colliders, the Standard Model predicts their spins to be correlated. The degree of correlation depends on both the production mechanism and properties of the top quark. Any deviation from the Standard Model prediction can be an indicator for new physics phenomena. The thesis employs an advanced top quark reconstruction algorithm including dedicated identification of the up- and down-type quarks from the W boson decay.
Search For Flavor Changing Neutral Current Top Quark Decays T Hq With H Bb In Pp Collisions At S 8 Tev With The Atlas Detector
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Author : Shota Tsiskaridze
language : en
Publisher: Springer
Release Date : 2017-08-02
Search For Flavor Changing Neutral Current Top Quark Decays T Hq With H Bb In Pp Collisions At S 8 Tev With The Atlas Detector written by Shota Tsiskaridze and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017-08-02 with Science categories.
This PhD thesis focuses on the search for flavor-changing neutral currents in the decay of a top quark to an up-type quark (q = u, c) and the Standard Model Higgs boson, where the Higgs boson decays to bb. Further, the thesis presents the combination of this search for top quark pair events with other ATLAS searches – in the course of which the most restrictive bounds to date on tqH interactions were obtained. Following on from the discovery of the Higgs boson, it is particularly important to measure the Yukawa couplings of the Standard Model fermions; these parameters may provide crucial insights to help solve the flavor puzzle and may help reveal the presence of new physics before it is directly observed in experiments.
Measurement Of The Ttbar Production Cross Section In The All Jets Final State In Pp Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2015
Measurement Of The Ttbar Production Cross Section In The All Jets Final State In Pp Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
The cross section for tt production in the all-jets final state is measured in pp collisions at a centre-of-mass energy of 8 TeV at the LHC with the CMS detector, in data corresponding to an integrated luminosity of 18.4 fb-1. The inclusive cross section is found to be 275.6 ±6.1 (stat) ± 37.8 (syst) ± 7.2 (lumi) pb. The normalized differential cross sections are measured as a function of the top quark transverse momenta, pT, and compared to predictions from quantum chromodynamics. The results are reported at detector, parton, and particle levels. In all cases, the measured top quark pT spectra are significantly softer than theoretical predictions.
Measurement Of Differential Cross Sections In The T Bar T U2192 L Jets Channel At U221a S
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Author :
language : en
Publisher:
Release Date : 2009
Measurement Of Differential Cross Sections In The T Bar T U2192 L Jets Channel At U221a S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with categories.
The analysis presented in this thesis focuses on kinematic distributions in the t$ar{t}$ system and studies in detail selected differential cross sections of top quarks as well as the reconstructed t$ar{t}$ pair, namely the top quark transverse momentum and the t$ar{t}$ system mass. The structure of the thesis is organized as follows: first the Standard Model of the particle physics is briefly introduced in Chapter 1, with relevant aspects of electroweak and strong interactions discussed. The physics of the top quark and its properties are then outlined in Chapter 2, together with the motivation for measuring the transverse top quark momentum and other kinematic-related variables of the t$ar{t}$ system. The concepts of present-day high energy physics collider experiments and the explicit example of Fermilab Tevatron collider and the D0 detector in Chapters 3 and 4 are followed by the description of basic detector-level objects, id est tracks, leptons and jets, in Chapter 5; their identification and calibration following in next chapter with the emphasis on the jet energy scale in Chapter 6 and jet identification at the D0. The analysis itself is outlined in Chapter 7 and is structured so that first the data and simulation samples and the basic preselection are described in Chapter 8 and 9, followed by the kinematic reconstruction part in Chapter 10. Chapter 11 on background normalization and Chapter 12 with raw reconstructed spectra results (at the detector-smeared level) are followed by the purity-based background subtraction method and examples of signal-level corrected spectra in Chapter 13. Next, the procedure of correcting measured spectra for detector effects (unfolding) is described in Chapters 14-15, including migration matrix studies, acceptance correction determination as well as the regularized unfolding procedure itself. Final differential cross sections are presented in Chapter 16 with the main results in Figures 16.19-16.20. Summary and discussion close the main analysis part in Chapter 17, supplemented by appendices on the wealthy of analysis control plots of the t$ar{t}$ → l + jets channel, selected D0 event displays and finally the list of publications and references. Preliminary results of this analysis have been documented in D0 internal notes [UnfoldTop], [p17Top], [p14Top]; as well as presented at conferences [APS08], [APS05]. The author has also been a co-author of more than 135 D0 collaboration publications since 2005. The author has taken part in the jet energy scale calibration efforts performing final closure tests and deriving a correction to jet energy offset due to the suppression of the calorimeter signal. The author has also co-performed the ?-intercalibration of the hadronic calorimeter and co-supervised the electromagnetic ?-intercalibration; recently has also been involved in maintaining the jet identification efficiencies measurement as a JetID convener. During the years in Fermilab, many events have taken place in the course of the analysis in persuasion, including more than 170 shifts served for the D0 detector with or without the beam, 168 talks presented with mixed results and reactions; and tens of thousands of code lines in C (and sometimes perhaps even really C++) written while terabytes of data were processed, analyzed, and sometimes also lost. It has been a long but profoundly enriching chapter of my life.
Measurement Of Ttbar Cross Sections In The Muon Jets Final State In Pp Collisions At 13 Tev
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Author : Andre Schmalfeld
language : en
Publisher:
Release Date : 2016
Measurement Of Ttbar Cross Sections In The Muon Jets Final State In Pp Collisions At 13 Tev written by Andre Schmalfeld and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
Top Pair Differential Cross Section Measurement In The Muon Jets Channel At Square Root
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Author : Tessa Pearson
language : en
Publisher:
Release Date : 2013
Top Pair Differential Cross Section Measurement In The Muon Jets Channel At Square Root written by Tessa Pearson and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
Measurement Of The W Jets Differential Cross Sections In P Bar P Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2016
Measurement Of The W Jets Differential Cross Sections In P Bar P Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
In this thesis the measurements of differential cross sections for the production of the $W$-boson in association with jets in $p\bar{p}$ collisions at $\sqrt{s} = 1.96$ TeV are presented. The measurements are based on 9.0 fb$^{-1}$ of CDF Run II data (i.e., the full dataset). Only events in which the W-boson decays leptonically (i.e., W 2!ev and W 2![mu]v)and at least one jet is present are considered. The lepton candidates are required to have a transverse energy $E^{\ell}_T> 25$GeV and pseudorapidity in the range l.
Measurement Of The Ttbar Production Cross Section In Ppbar Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2010
Measurement Of The Ttbar Production Cross Section In Ppbar Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010 with categories.
We present a measurement of the top quark pair production cross section in p{bar p} collisions at √s = 1.96 TeV using a data sample corresponding to 1.7 fb−1 of integrated luminosity collected with the Collider Detector at Fermilab. We reconstruct t{bar t} events in the lepton+jets channel, consisting of e[nu]+jets and [mu][nu]+jets final states. The dominant background is the production of W bosons in association with multiple jets. To suppress this background, we identify electrons from the semileptonic decay of heavy-flavor jets ('soft electron tags'). From a sample of 2196 candidate events, we obtain 120 tagged events with a background expectation of 51 ± 3 events, corresponding to a cross section of [sigma]{sub t{bar t}} = 7.8 ± 2.4 (stat) ± 1.6 (syst) ± 0.5 (lumi) pb. We assume a top-quark mass of 175 GeV/c2. This is the first measurement of the t{bar t} cross section with soft electron tags in Run II of the Tevatron.
Measurement Of Differential Cross Sections For The Production Of Top Quark Pairs And Of Additional Jets In Lepton Jets Events From Pp Collisions At S
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Author : CMS Collaboration
language : en
Publisher:
Release Date : 2018
Measurement Of Differential Cross Sections For The Production Of Top Quark Pairs And Of Additional Jets In Lepton Jets Events From Pp Collisions At S written by CMS Collaboration and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with categories.