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Author : Felix Höhle
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (981 download)
Download or read book Measurement of Spin Correlation in Dileptonic Top Quark Pair Decays with the CMS Experiment written by Felix Höhle and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 117 pages
Book Rating : 4.:/5 (986 download)
Download or read book Measurement of the Spin Correlation in the Top Quark Pair Production Using the Dilepton Events in 1.96-TeV Proton-Antiproton Collisions written by and published by . This book was released on 2012 with total page 117 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Boris Lemmer
Publisher : Springer
ISBN 13 : 3319189328
Total Pages : 246 pages
Book Rating : 4.3/5 (191 download)
Download or read book Spin Correlations in tt Events from pp Collisions written by Boris Lemmer and published by Springer. This book was released on 2015-06-24 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Author :
Publisher :
ISBN 13 :
Total Pages : 249 pages
Book Rating : 4.:/5 (931 download)
Download or read book Measurement of Spin Correlations in Top/Anti-Top Events from Pp Collisions at Sqrt(s) written by and published by . This book was released on 2014 with total page 249 pages. Available in PDF, EPUB and Kindle. Book excerpt: The top quark decays before it hadronises. Before its spin state can be changed in a process of strong interaction, it is directly transferred to the top quark decay products. The top quark spin can be deduced by studying angular distributions of the decay products. The Standard Model predicts the top/anti-top quark (tt) pairs to have correlated spins. The degree is sensitive to the spin and the production mechanisms of the top quark. Measuring the spin correlation allows to test the predictions. New physics e ects can be reflected in deviations from the prediction. In this thesis the spin ...
Download or read book Measurements of Tt{u00AF} Spin Correlations and Top Quark Polarization Using Dilepton Final States in Pp Collisions at S written by and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We presented measurements of the top quark-antiquark (tt¯) spin correlations and the top quark polarization for tt¯ pairs produced in pp collisions at √s=8 TeV. The data correspond to an integrated luminosity of 19.5 fb-1 collected with the CMS detector at the LHC. The measurements are performed using events with two oppositely charged leptons (electrons or muons) and two or more jets, where at least one of the jets is identified as originating from a bottom quark. The spin correlations and polarization are measured from the angular distributions of the two selected leptons, both inclusively and differentially, with respect to the invariant mass, rapidity, and transverse momentum of the tt¯ system. Moreover, the measurements are unfolded to the parton level and found to be in agreement with predictions of the standard model. A search for new physics in the form of anomalous top quark chromo moments is performed. Lastly, no evidence of new physics is observed, and exclusion limits on the real part of the chromo-magnetic dipole moment and the imaginary part of the chromo-electric dipole moment are evaluated.
Author : Boris Lemmer
Publisher :
ISBN 13 : 9783319189338
Total Pages : 0 pages
Book Rating : 4.1/5 (893 download)
Download or read book Spin Correlations in Tt Events from Pp Collisions written by Boris Lemmer and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Spin Measurement in Top Quark Events at the LHC. written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Measurements of polarisation and spin correlations are presented in events with top quarks produced in pp collisions at the LHC. The data correspond to integrated luminosities of $5 fb^{-1}$ at $\sqrt{s}$ = 7 TeV and 20 $fb^{-1}$ at $\sqrt{s}$ = 8 TeV collected with the ATLAS and CMS detectors. The top quark polarization is measured in both single top quark production in the t-channel and $t\bar{t}$ pair-production, from the angular distributions of charged leptons in the rest frame of their parent top quark. The spin correlations are measured in $t\bar{t}$ events using various angular distributions of the decay products. The measurements are made using both template fitting methods and by unfolding the distributions to the parton-level, where differential measurements with respect to the invariant mass, rapidity, and transverse momentum of the $t\bar{t}$ system are also made. The spin correlation measurements are used to search for new physics in the form of a light top squark or an anomalous top quark chromo-magnetic dipole moment. All measurements are found to be in agreement with predictions of the standard model.
Author : Nathan Mirman
Publisher :
ISBN 13 :
Total Pages : 390 pages
Book Rating : 4.:/5 (1 download)
Download or read book Measurement of the Top Quark Mass in the Dileptonic Decay Channel at CMS written by Nathan Mirman and published by . This book was released on 2017 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation presents a measurement of the top quark mass (Mt) in the dileptonic decay channel using data from proton-proton collisions at sqrt(s) = 8 TeV recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 19.7 ± 0.5 fb-1. The analysis is based on three observables whose distributions are sensitive to the value of Mt. The Mbl invariant mass and MT2 'stransverse mass' observables are employed in a simultaneous fit to determine the value of Mt and an overall jet energy scale factor (JSF). In a complementary approach, the MT2-assisted on-shell reconstruction technique is used to construct an Mblv invariant mass observable that is combined with MT2 to measure Mt. The shapes of the observables, along with their evolutions in Mt and JSF, are modeled by a non-parametric Gaussian process regression technique. The sensitivity of the observables to the value of Mt is investigated using a Fisher information density function. The top quark mass is measured to be 172.22 ± 0.18 (stat) ± 0.91 (syst) GeV. This dissertation also presents a missing transverse momentum (MET) significance variable, which is used to estimate the compatibility of the reconstructed MET with a zero nominal value. This variable may be used to discriminate between events containing real MET due to undetected particles and spurious MET due to object misreconstruction, finite detector resolution, or detector noise. The MET significance variable is tuned using data-driven techniques, and its performance is evaluated using the CMS Run 1 and Run 2 datasets. ...
Download or read book Measurement of Spin Correlation in Top-Antitop Quark Events and Search for Top Squark Pair Production in Pp Collisions at S written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a measurement of spin correlation in t¯t production using data collected with the ATLAS detector at the Large Hadron Collider in proton-proton collisions at a center-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 20.3 fb−1. The correlation between the top and antitop quark spins is extracted from dilepton t¯t events by using the difference in the azimuthal angle between the two charged leptons in the laboratory frame. In the helicity basis the measured degree of correlation corresponds to Ahelicity = 0.38±0.04, in agreement with the standard model prediction. A search is performed for pair production of top squarks with masses close to the top quark mass decaying to predominantly right-handed top quarks and a light neutralino, the lightest supersymmetric particle. Lastly, top squarks with masses between the top quark mass and 191 GeV are excluded at the 95% confidence level.
Author : Simon James Head
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (113 download)
Download or read book Spin Correlation in the Dileptonic Decay of Top Quark Pairs at ATLAS. written by Simon James Head and published by . This book was released on 2009 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Susan J. Dittmer
Publisher :
ISBN 13 :
Total Pages : 350 pages
Book Rating : 4.:/5 (16 download)
Download or read book Measurement of Boosted Differential Top Quark Pair Production Cross Section at 13 TeV with the CMS Detector written by Susan J. Dittmer and published by . This book was released on 2017 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes a measurement of the differential top quark pair production cross section for top quarks with high transverse momentum (pt) in proton-proton collisions at a center-of-mass energy of 13 TeV. The measurement is performed using data collected by the CMS experiment during the 2016 data-taking period, corresponding to an integrated luminosity of 35.9 fb-1. The measurement is performed using events where one top quark decays hadronically and is reconstructed as a single large-radius t jet with pt > 400 GeV, while the other top quark decays leptonically to a b jet, an electron or a muon, and a neutrino. Jet substructure techniques are used to identify the large-radius jet as a t jet candidate. The measurement demonstrates that current simulations overpredict the rate of top quark pair production at high pt, providing valuable feedback on the accuracy of current simulation.
Author :
Publisher :
ISBN 13 :
Total Pages : 26 pages
Book Rating : 4.:/5 (16 download)
Download or read book Measurement of Spin Correlations in T-tbar Production Using the Matrix Element Method in the Muon+jets Final State in Pp Collisions at {u221A}(s) written by and published by . This book was released on 2016 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: The consistency of the spin correlation strength in top quark pair production with the standard model (SM) prediction is tested in the muon+jets final state. The events are selected from pp collisions, collected by the CMS detector, at a centre-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 19.7 fb-1. We then compare the data with the expectation for the spin correlation predicted by the SM and with the expectation of no correlation. Furthermore, by using a template fit method, the fraction of events that show SM spin correlations is measured to be 0.72 ±0.08 (stat)+0.15 -0.13 (syst), representing the most precise measurement of this quantity in the lepton+jets final state to date.
Download or read book Measurements of Spin Correlation in Top-antitop Quark Events from Proton-proton Collisions at [math Display written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present measurements of spin correlation in top quark pair production using data collected with the ATLAS detector at the LHC with proton-proton collisions at a center-of-mass energy of 7 TeV, corresponding to an integrated luminosity of 4.6 fb1. Events are selected in final states with two charged leptons and at least two jets and in final states with one charged lepton and at least four jets. Four different observables sensitive to different properties of the top quark pair production mechanism are used to extract the correlation between the top and antitop quark spins. Some of these observables are measured for the first time. The measurements are in good agreement with the Standard Model prediction at next-to-leading-order accuracy.
Download or read book Measurements of Spin Correlation in Top-antitop Quark Events from Proton-proton Collisions at S written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present measurements of spin correlation in top quark pair production using data collected with the ATLAS detector at the LHC with proton-proton collisions at a center-of-mass energy of 7 TeV, corresponding to an integrated luminosity of 4.6 fb−1. Events are selected in final states with two charged leptons and at least two jets and in final states with one charged lepton and at least four jets. Four different observables sensitive to different properties of the top quark pair production mechanism are used to extract the correlation between the top and antitop quark spins. Some of these observables are measured for the first time. The measurements are in good agreement with the Standard Model prediction at next-to-leading-order accuracy.
Author :
Publisher :
ISBN 13 :
Total Pages : 31 pages
Book Rating : 4.:/5 (16 download)
Download or read book Measurement of the Top Quark Pair Production Cross Section in Pp Collisions at Sqrt(s) written by and published by . This book was released on 2012 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt: The top quark pair production cross section is measured in dilepton events with one electron or muon, and one hadronically decaying tau lepton from the decay t anti-t to (l nu(l)) (tau nu(tau)) b anti-b, where l can be either an electron or a muon. The data sample corresponds to an integrated luminosity of 2.0 inverse femtobarns for the electron channel and 2.2 inverse femtobarns for the muon channel, collected by the CMS detector at the LHC. This is the first measurement of the t anti-t cross section explicitly including tau leptons in proton-proton collisions at sqrt(s)=7 TeV. The measured value sigma(t anti-t) = 143 +/- 14 (stat.) +/- 22 (syst.) +/- 3 (lumi.) pb is consistent with the standard model predictions.
Author : Simon Spannagel
Publisher : Springer
ISBN 13 : 331958880X
Total Pages : 286 pages
Book Rating : 4.3/5 (195 download)
Download or read book CMS Pixel Detector Upgrade and Top Quark Pole Mass Determination written by Simon Spannagel and published by Springer. This book was released on 2017-08-01 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis addresses two different topics, both vital for implementing modern high-energy physics experiments: detector development and data analysis. Providing a concise introduction to both the standard model of particle physics and the basic principles of semiconductor tracking detectors, it presents the first measurement of the top quark pole mass from the differential cross-section of tt+J events in the dileptonic tt decay channel. The first part focuses on the development and characterization of silicon pixel detectors. To account for the expected increase in luminosity of the Large Hadron Collider (LHC), the pixel detector of the compact muon solenoid (CMS) experiment is replaced by an upgraded detector with new front-end electronics. It presents comprehensive test beam studies conducted to verify the design and quantify the performance of the new front-end in terms of tracking efficiency and spatial resolution. Furthermore, it proposes a new cluster interpolation method, which utilizes the third central moment of the cluster charge distribution to improve the position resolution. The second part of the thesis introduces an alternative measurement of the top quark mass from the normalized differential production cross-sections of dileptonic top quark pair events with an additional jet. The energy measurement is 8TeV. Using theoretical predictions at next-to-leading order in perturbative Quantum Chromodynamics (QCD), the top quark pole mass is determined using a template fit method.
Author : Christine Angela McLean
Publisher :
ISBN 13 : 9780355969658
Total Pages : pages
Book Rating : 4.9/5 (696 download)
Download or read book Search for High-mass Top Quark Pair Resonances with the CMS Experiment written by Christine Angela McLean and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: I present a search for new massive particles decaying to a pair of top quarks with the CMS detector at the LHC, using 36 fb−1 of proton-proton collision data recorded in 2016, at a center-of-mass energy of 13 TeV. In the high mass ranges accessible by the LHC at these energies, the top quarks are produced with high transverse momenta: the products of hadronically decaying top quarks are reconstructed as a single jet. Specific reconstruction algorithms and selections are employed to address the identification of boosted top quark signatures. The search is performed by measuring the invariant mass distribution of the top-quark pair and testing for deviations from the expected Standard Model background. The results are presented in terms of expected upper limits on the production cross section of several models, including those of Randall-Sundrum Kaluza-Klein gluon and Z′ boson production. The results are then compared with those of previous searches.
