Measurement of Differential Cross Sections for Top Quark Pair Production Using the Lepton+jets Final State in Proton-proton Collisions at 13 TeV.

Measurement of Differential Cross Sections for Top Quark Pair Production Using the Lepton+jets Final State in Proton-proton Collisions at 13 TeV.
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Release: 2016
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Differential and double-differential cross sections for the production of top quark pairs in proton-proton collisions at 13 TeV are measured as a function of jet multiplicity and of kinematic variables of the top quarks and the top quark-antiquark system. This analysis is based on data collected by the CMS experiment at the LHC corresponding to an integrated luminosity of 2.3 inverse femtobarns. The measurements are performed in the lepton+jets decay channels with a single muon or electron in the final state. The differential cross sections are presented at particle level, within a phase space close to the experimental acceptance, and at parton level in the full phase space. The results are compared to several standard model predictions.

Top-Quark Pair Production Cross Sections and Calibration of the Top-Quark Monte-Carlo Mass

Top-Quark Pair Production Cross Sections and Calibration of the Top-Quark Monte-Carlo Mass
Author: Jan Kieseler
Publisher: Springer
Total Pages: 172
Release: 2016-06-15
Genre: Science
ISBN: 3319400053

This thesis presents the first experimental calibration of the top-quark Monte-Carlo mass. It also provides the top-quark mass-independent and most precise top-quark pair production cross-section measurement to date. The most precise measurements of the top-quark mass obtain the top-quark mass parameter (Monte-Carlo mass) used in simulations, which are partially based on heuristic models. Its interpretation in terms of mass parameters used in theoretical calculations, e.g. a running or a pole mass, has been a long-standing open problem with far-reaching implications beyond particle physics, even affecting conclusions on the stability of the vacuum state of our universe. In this thesis, this problem is solved experimentally in three steps using data obtained with the compact muon solenoid (CMS) detector. The most precise top-quark pair production cross-section measurements to date are performed. The Monte-Carlo mass is determined and a new method for extracting the top-quark mass from theoretical calculations is presented. Lastly, the top-quark production cross-sections are obtained – for the first time – without residual dependence on the top-quark mass, are interpreted using theoretical calculations to determine the top-quark running- and pole mass with unprecedented precision, and are fully consistently compared with the simultaneously obtained top-quark Monte-Carlo mass.

Measurement of the Integrated and Differential Tt{u00AF} Production Cross Sections for High- PT Top Quarks in Pp Collisions at S

Measurement of the Integrated and Differential Tt{u00AF} Production Cross Sections for High- PT Top Quarks in Pp Collisions at S
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Release: 2016
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The cross section for pair production of top quarks ($tar{t}$) with high transverse momenta is measured in pp collisions, collected with the CMS detector at the LHC with √s=8 TeV in data corresponding to an integrated luminosity of 19.7 fb-1. The measurement is performed using lepton+jets events, where one top quark decays semileptonically, while the second top quark decays to a hadronic final state. The hadronic decay is reconstructed as a single, large-radius jet, and identified as a top quark candidate using jet substructure techniques. The integrated cross section and the differential cross sections as a function of top quark pT and rapidity are measured at particle level within a fiducial region related to the detector-level requirements and at parton level. The particle-level integrated cross section is found to be ?$tar{t}$ = 0.499 ± 0.035(stat+syst) ± 0.095(theo) ± 0.013(lumi) pb for top quark pT > 400 GeV. The parton-level measurement is ?$tar{t}$ = 1.44 ± 0.10(stat+syst) ± 0.29(theo) ± 0.04(lumi) pb. Lastly, the integrated and differential cross section results are compared to predictions from several event generators.

Measurement of the Integrated and Differential T-tbar Production Cross Sections for High-pt Top Quarks in Pp Collisions at $\sqrt{s}$

Measurement of the Integrated and Differential T-tbar Production Cross Sections for High-pt Top Quarks in Pp Collisions at $\sqrt{s}$
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Release: 2016
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The cross section for pair production of top quarks (t-tbar) with high transverse momenta is measured in pp collisions, collected with the CMS detector at the LHC with sqrt(s) = 8 TeV in data corresponding to an integrated luminosity of 19.7 inverse-femtobarns. The measurement is performed using lepton+jets events, where one top quark decays semileptonically, while the second top quark decays to a hadronic final state. The hadronic decay is reconstructed as a single, large-radius jet, and identified as a top quark candidate using jet substructure techniques. The integrated cross section and the differential cross sections as a function of top quark pt and rapidity are measured at particle level within a fiducial region related to the detector-level requirements and at parton level. The particle-level integrated cross section is found to be sigma[t-tbar] = 0.499 +/- 0.035 (stat+syst) +/- 0.095 (theory) +/- 0.013 (lumi) pb for top quark pt> 400 GeV. The parton-level measurement is sigma[t-tbar] = 1.44 +/- 0.10 (stat+syst) +/- 0.29 (theory) +/- 0.04 (lumi) pb. The integrated and differential cross section results are compared to predictions from several event generators.

Top Quark Physics at Hadron Colliders

Top Quark Physics at Hadron Colliders
Author: Arnulf Quadt
Publisher: Springer Science & Business Media
Total Pages: 166
Release: 2007-08-16
Genre: Science
ISBN: 3540710604

This will be a required acquisition text for academic libraries. More than ten years after its discovery, still relatively little is known about the top quark, the heaviest known elementary particle. This extensive survey summarizes and reviews top-quark physics based on the precision measurements at the Fermilab Tevatron Collider, as well as examining in detail the sensitivity of these experiments to new physics. Finally, the author provides an overview of top quark physics at the Large Hadron Collider.

Measurement of the Differential Cross Sections for Top Quark Pair Production as a Function of Kinematic Event Variables in Pp Collisions at $\sqrt{s}$

Measurement of the Differential Cross Sections for Top Quark Pair Production as a Function of Kinematic Event Variables in Pp Collisions at $\sqrt{s}$
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Release: 2016
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Measurements are reported of the normalized differential cross sections for top quark pair production with respect to four kinematic event variables: the missing transverse energy; the scalar sum of the jet transverse momentum (pT); the scalar sum of the pT of all objects in the event; and the pT of leptonically decaying W bosons from top quark decays. The data sample, collected using the CMS detector at the LHC, consists of 5.0 inverse-femtobarns of proton-proton collisions at sqrt(s) = 7 TeV and 19.7 inverse-femtobarns at sqrt(s) = 8 TeV. Top quark pair events containing one electron or muon are selected. The results are presented after correcting for detector effects to allow direct comparison with theoretical predictions. No significant deviations from the predictions of several standard model event simulation generators are observed.

Measurement of the Differential Cross Sections for Top Quark Pair Production as a Function of Kinematic Event Variables in Pp Collisions at S

Measurement of the Differential Cross Sections for Top Quark Pair Production as a Function of Kinematic Event Variables in Pp Collisions at S
Author:
Publisher:
Total Pages:
Release: 2016
Genre:
ISBN:

Measurements are reported of the normalized differential cross sections for top quark pair production with respect to four kinematic event variables: the missing transverse energy; the scalar sum of the jet transverse momentum (pT); the scalar sum of the pT of all objects in the event; and the pT of leptonically decaying W bosons from top quark decays. The data sample, collected using the CMS detector at the LHC, consists of 5.0 fb–1 of proton-proton collisions at √s = 7 TeV and 19.7 fb–1 at √s = 8 TeV. Top quark pair events containing one electron or muon are selected. The results are presented after correcting for detector effects to allow direct comparison with theoretical predictions. In conclusion, no significant deviations from the predictions of several standard model event simulation generators are observed.