Measurement of the Production Cross-section of a Single Top Quark in Association with a W Boson at 8 TeV with the ATLAS Experiment

Measurement of the Production Cross-section of a Single Top Quark in Association with a W Boson at 8 TeV with the ATLAS Experiment PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 48

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Book Description
The cross-section for the production of a single top quark in association with a W boson in proton-proton collisions at √s = 8 is measured. The dataset corresponds to an integrated luminosity of 20.3 fb-1, collected by the ATLAS detector in 2012 at the Large Hadron Collider at CERN. Events containing two leptons and one central b-jet are selected. The Wt signal is separated from the backgrounds using boosted decision trees, each of which combines a number of discriminating variables into one classifier. Production of Wt events is observed with a significance of 7.7[sigma]. The cross-section is extracted in a profile likelihood fit to the classifier output distributions. The Wt cross-section, inclusive of decay modes, is measured to be 23.0±1.3(stat.)-3.5+3.2(syst.)±1.1(lumi.) pb. The measured cross-section is used to extract a value for the CKM matrix element.

Measurement of the Production Cross-section of a Single Top Quark in Association with a W Boson at 8 TeV with the ATLAS Experiment

Measurement of the Production Cross-section of a Single Top Quark in Association with a W Boson at 8 TeV with the ATLAS Experiment PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 48

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Book Description
The cross-section for the production of a single top quark in association with a W boson in proton-proton collisions at √s = 8 is measured. The dataset corresponds to an integrated luminosity of 20.3 fb-1, collected by the ATLAS detector in 2012 at the Large Hadron Collider at CERN. Events containing two leptons and one central b-jet are selected. The Wt signal is separated from the backgrounds using boosted decision trees, each of which combines a number of discriminating variables into one classifier. Production of Wt events is observed with a significance of 7.7[sigma]. The cross-section is extracted in a profile likelihood fit to the classifier output distributions. The Wt cross-section, inclusive of decay modes, is measured to be 23.0±1.3(stat.)-3.5+3.2(syst.)±1.1(lumi.) pb. The measured cross-section is used to extract a value for the CKM matrix element.

Top Quark Pair Production

Top Quark Pair Production PDF Author: Anna Christine Henrichs
Publisher:
ISBN: 9783319014883
Category :
Languages : en
Pages : 240

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Book Description


Measurement of the T-channel Single-top-quark Production Cross Section and of the

Measurement of the T-channel Single-top-quark Production Cross Section and of the PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 43

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Book Description
Measurements are presented of the t-channel single-top-quark production cross section in proton-proton collisions at √s = 8 TeV. The results are based on a data sample corresponding to an integrated luminosity of 19.7 fb−1 recorded with the CMS detector at the LHC. The cross section is measured inclusively, as well as separately for top (t) and antitop $ \left(\overline{\mathrm{t}}\right) $, in final states with a muon or an electron. The measured inclusive t-channel cross section is?t-ch. = 83.6 ± 2.3 (stat.) ± 7.4 (syst.) pb. The single t and $ \overline{\mathrm{t}} $ cross sections are measured to be?t-ch.(t) = 53.8 ± 1.5 (stat.) ± 4.4 (syst.) pb and?$_{t-ch.}$ $ \left(\overline{t}\right) $ = 27.6 ± 1.3 (stat.) ± 3.7 (syst.) pb, respectively. The measured ratio of cross sections is Rt-ch. =?t-ch.(t)/?t-ch. $ \left(\overline{\mathrm{t}}\right) $ = 1.95 ± 0.10 (stat.) ± 0.19 (syst.), in agreement with the standard model prediction. The modulus of the Cabibbo-Kobayashi-Maskawa matrix element Vtb is extracted and, in combination with a previous CMS result at √s = 7 TeV, a value.

The Higgs Boson Produced With Top Quarks in Fully Hadronic Signatures

The Higgs Boson Produced With Top Quarks in Fully Hadronic Signatures PDF Author: Daniel Salerno
Publisher: Springer Nature
ISBN: 3030312577
Category : Science
Languages : en
Pages : 207

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Book Description
The work presented in this PhD dissertation is the first search at CMS for Higgs bosons produced in association with top quarks (ttH) in a final state consisting of only jets. The results presented in this book uncover a new class of ttH events that will help us elucidate our understanding of the Yukawa sector interactions between the Higgs boson and the top quark. Despite this being the most common decay signature for ttH, a large contamination of SM backgrounds makes it the most challenging for extracting a signal from data. The PhD thesis presents many sophisticated tools and techniques that were developed in order to overcome these challenges. These tools pave the way for future analyses to investigate other standard model and beyond-standard model physics.

Spin Correlations in tt Events from pp Collisions

Spin Correlations in tt Events from pp Collisions PDF Author: Boris Lemmer
Publisher: Springer
ISBN: 3319189328
Category : Science
Languages : en
Pages : 246

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Book Description
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 New Heavy Charged Bosons and Measurement of High-Mass Drell-Yan Production in Proton—Proton Collisions

Search for New Heavy Charged Bosons and Measurement of High-Mass Drell-Yan Production in Proton—Proton Collisions PDF Author: Markus Zinser
Publisher: Springer
ISBN: 3030006506
Category : Science
Languages : en
Pages : 386

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Book Description
This book presents two analyses, the first of which involves the search for a new heavy charged gauge boson, a so-called W' boson. This new gauge boson is predicted by some theories extending the Standard Model gauge group to solve some of its conceptual problems. Decays of the W' boson in final states with a lepton (l± = e± , μ±) and the corresponding (anti-)neutrino are considered. Data collected by the ATLAS experiment in 2015 at a center of mass energy of √s =13 TeV is used for the analysis. In turn, the second analysis presents a measurement of the double-differential cross section of the process pp->Z/gamma^* + X -> l^+l^- + X, including a gamma gamma induced contribution, at a center of mass energy of sqrt{s} = 8 TeV. The measurement is performed in an invariant mass region of 116 GeV to 1500 GeV as a function of invariant mass and absolute rapidity of the l^+l^-- pair, and as a function of invariant mass and pseudorapidity separation of the l^+l^-- pair. The data analyzed was recorded by the ATLAS experiment in 2012 and corresponds to an integrated luminosity of 20.3/fb. It is expected that the measured cross sections are sensitive to the PDFs at very high values of the Bjorken-x scaling variable, and to the photon structure of the proton.

Measurement of the Production Cross Section of a Top-antitop Quark Pair in Association with a Z Boson at Root from S Equals 13 TeV with the ATLAS Detector

Measurement of the Production Cross Section of a Top-antitop Quark Pair in Association with a Z Boson at Root from S Equals 13 TeV with the ATLAS Detector PDF Author: Florian Christoph Maria Fischer
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Associated Production of W + Charm in 13 TeV Proton-Proton Collisions Measured with CMS and Determination of the Strange Quark Content of the Proton

Associated Production of W + Charm in 13 TeV Proton-Proton Collisions Measured with CMS and Determination of the Strange Quark Content of the Proton PDF Author: Svenja Karen Pflitsch
Publisher: Springer Nature
ISBN: 303052762X
Category : Science
Languages : en
Pages : 148

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Book Description
The associated production of a W boson and a single charm quark (W+c) is the only process in proton-proton collisions that directly probes the strange quark content of the proton. In this thesis, W+charm production is measured in proton-proton collisions at the LHC at 13 TeV, as recorded by the Compact Muon Solenoid (CMS) experiment. The analysis focuses on the identification of W bosons in their leptonic decay to a muon and a neutrino and charm quarks are tagged via the full reconstruction of D*-Mesons. The measured cross sections of W+c production are used, in combination with other relevant CMS results and the most precise HERA DIS data, in a QCD analysis to determine the strange quark content of the proton. The resulting strange quark distribution and suppression, with respect to the other light sea quarks, are in good agreement with those obtained in neutrino scattering experiments and extend their kinematic reach.

Measurement of the Production Cross-section of Single Top Quarks in Association with W Bosons at ATLAS

Measurement of the Production Cross-section of Single Top Quarks in Association with W Bosons at ATLAS PDF Author: Francesco Michelangelo Giorgi
Publisher:
ISBN:
Category :
Languages : en
Pages :

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New Era For Cp Asymmetries: Axions And Rare Decays Of Hadrons And Leptons

New Era For Cp Asymmetries: Axions And Rare Decays Of Hadrons And Leptons PDF Author: Ikaros I Bigi
Publisher: World Scientific
ISBN: 9813233095
Category : Science
Languages : en
Pages : 354

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Book Description
This book is dedicated to Lev Okun, who passed away in November 2015. He was a true pioneer in probing fundamental dynamics.The book has two objectives. First is to showcase Okun's impact for decades since 1963, when he published his remarkable book Weak Interaction of Elementary Particles. Second is to present the current progress of our scientific community in the studies of our Universe. New directions and possible future developments are discussed, often using the past as a guide. The authors mostly focus on CP asymmetries in the transitions of hadrons and leptons, but they also discuss their rare decays, and talk about axions and supersymmetry, and possible connections with dark matter, extra dimensions, baryogenesis and multiverse.This book is suitable for readers who know quantum mechanics and quantum field theories in general.