Search for Wt-channel Single Top Quark Production in 7 TeV Proton-proton Collisions Using the ATLAS Detector

Search for Wt-channel Single Top Quark Production in 7 TeV Proton-proton Collisions Using the ATLAS Detector PDF Author: Dominique Tardif
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ISBN:
Category :
Languages : en
Pages :

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Search for Wt-channel Single Top Quark Production in 7 TeV Proton-proton Collisions Using the ATLAS Detector

Search for Wt-channel Single Top Quark Production in 7 TeV Proton-proton Collisions Using the ATLAS Detector PDF Author: Dominique Tardif
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Top Quark Pair Production

Top Quark Pair Production PDF Author: Anna Christine Henrichs
Publisher: Springer Science & Business Media
ISBN: 3319014870
Category : Science
Languages : en
Pages : 231

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Book Description
Before any kind of new physics discovery could be made at the LHC, a precise understanding and measurement of the Standard Model of particle physics' processes was necessary. The book provides an introduction to top quark production in the context of the Standard Model and presents two such precise measurements of the production of top quark pairs in proton-proton collisions at a center-of-mass energy of 7 TeV that were observed with the ATLAS Experiment at the LHC. The presented measurements focus on events with one charged lepton, missing transverse energy and jets. Using novel and advanced analysis techniques as well as a good understanding of the detector, they constitute the most precise measurements of the quantity at that time.

Search for S Channel Single Top Quark Production in Pp Collisions at $\sqrt{s}$

Search for S Channel Single Top Quark Production in Pp Collisions at $\sqrt{s}$ PDF Author:
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Category :
Languages : en
Pages :

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A search is presented for single top quark production in the s channel in proton-proton collisions with the CMS detector at the CERN LHC in decay modes of the top quark containing a muon or an electron in the final state. The signal is extracted through a maximum-likelihood fit to the distribution of a multivariate discriminant defined using boosted decision trees to separate the expected signal contribution from background processes. Data collected at centre-of-mass energies of 7 and 8 TeV yield cross sections of 7.1 +/- 8.1 pb and 13.4 +/- 7.3 pb, respectively, and a best fit value of 2.0 +/- 0.9 for the combined ratio of the measured and expected values. The signal significance is 2.5 standard deviations, and the upper limit on the rate relative to the standard model expectation is 4.7 at 95% confidence level.

Measurements of Differential T-channel Single Top-quark Production Cross-sections in Proton–proton Collisions at a Centre-of-mass Energy of 8 TeV with the ATLAS Detector

Measurements of Differential T-channel Single Top-quark Production Cross-sections in Proton–proton Collisions at a Centre-of-mass Energy of 8 TeV with the ATLAS Detector PDF Author: Pienpen Seema-Mergelmeyer
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Search for Single Top-quark Production Via Flavour-changing Neutral Currents at 8 TeV with the ATLAS Detector

Search for Single Top-quark Production Via Flavour-changing Neutral Currents at 8 TeV with the ATLAS Detector PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 30

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Book Description
A search for single top-quark production via flavour-changing neutral current processes from gluon plus up- or charm-quark initial states in proton-proton collisions at the LHC is presented. Data collected with the ATLAS detector in 2012 at a centre-of-mass energy of 8 TeV and corresponding to an integrated luminosity of 20.3 fb-1 are used. Furthermore, candidate events for a top quark decaying into a lepton, a neutrino and a jet are selected and classified into signal- and background-like candidates using a neural network.

Electroweak Physics at the Large Hadron Collider with the ATLAS Detector

Electroweak Physics at the Large Hadron Collider with the ATLAS Detector PDF Author: Elodie Resseguie
Publisher: Springer Nature
ISBN: 3030570169
Category : Science
Languages : en
Pages : 336

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Book Description
This thesis discusses searches for electroweakly produced supersymmetric partners of the gauge and the Higgs bosons (gauginos and higgsinos) decaying to multiple leptons, using pp collisions at sqrt(s) = 13 TeV. The thesis presents an in-depth study of multiple searches, as well as the first 13 TeV cross section measurement for the dominant background in these searches, WZ production. Two searches were performed using 36.1/fb of data: the gaugino search, which makes use of a novel kinematic variable, and the higgsino search, which produced the first higgsino limits at the LHC. A search using 139/fb of data makes use of a new technique developed in this thesis to cross check an excess of data above the background expectation in a search using a Recursive Jigsaw Reconstruction technique. None of the searches showed a significant excess of data, and limits were expanded with respect to previous results. These searches will benefit from the addition of luminosity during HL-LHC; however, the current detector will not be able to withstand the increase in radiation. Electronics for the detector upgrade are tested and irradiated to ensure their performance.

Search for Quark Compositeness in 7 TeV Proton-proton Collisions with the ATLAS Detector at the Large Hadron Collider

Search for Quark Compositeness in 7 TeV Proton-proton Collisions with the ATLAS Detector at the Large Hadron Collider PDF Author: Frank Berghaus
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description
Quarks and leptons are assumed to be fundamental particles in the Standard Model of particle physics. The Large Hadron Collider provided 7 TeV proton-proton collisions in 2010. These collisions permit the search for quark substructure at a smaller length scale than was previously possible. This thesis is an investigation of the angular distribution of high dijet mass events in 36 pb^{-1} of data recorded by the ATLAS detector. Further contributions to technical aspects of the analysis are described in the appendices. This analysis excludes quark substructure at?

Measurement of the Top Quark Pair Production Cross Section in Proton-proton Collisions at Center -o-mass-energies of 7 TeV in Final States with a [tau] Lepton with the ATLAS Detector

Measurement of the Top Quark Pair Production Cross Section in Proton-proton Collisions at Center -o-mass-energies of 7 TeV in Final States with a [tau] Lepton with the ATLAS Detector PDF Author: Universitat de València. Facultat de Física
Publisher:
ISBN:
Category :
Languages : en
Pages : 184

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Search for W' Boson with Boosted and Hadronic Top-quark Final State in Pp Collisions at 8́(s

Search for W' Boson with Boosted and Hadronic Top-quark Final State in Pp Collisions at 8́(s PDF Author: Kuan-Yu Lin
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 181

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Book Description
With the LHC proton-proton collision data at an energy of 13 TeV recorded by the ATLAS detector, this analysis searches for the production of a new particle W' with a yet-to-be-probed mass in the top quark plus bottom quark decay channel. The boosted and hadronically decaying top-quark is reconstructed as a large-radius jet and identified using jet substructures. A secondary-vertex finding algorithm identifies small-radius jets originating from a bottom quark. After the identification stage, the main background events come from the Quantum Chromodynamical production of multi-jet, which is estimated by a data-driven approach. The statistical data analysis searches for a resonant peak in the invariant mass distribution of the system with a jet associated with the top quark and another with the bottom quark. The consistency between data and the background prediction is found in the invariant mass range between 1 TeV to 7 TeV, and an upper limit at the 95% confidence level is set on the production cross-section times branching ratio for a W' boson with right-handed chirality decaying to a top quark and a bottom quark. A lower limit on the W' mass is set at 4.4 TeV accordingly.

Measurement of the Top Quark Pair Production Cross Section and an In-situ B-tagging Efficiency Calibration with ATLAS in Proton-proton Collisions at Center of Mass Energy

Measurement of the Top Quark Pair Production Cross Section and an In-situ B-tagging Efficiency Calibration with ATLAS in Proton-proton Collisions at Center of Mass Energy PDF Author: Bin Guo
Publisher:
ISBN: 9780494782064
Category :
Languages : en
Pages : 234

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Book Description
We present a measurement of the top anti-top quark (tt ̄ ) production cross section in the dilepton final states from proton-proton collisions at a center of mass energy at 7 TeV at the LHC. A b-tagging algorithm based on tracks displaced from the event interaction vertex is applied to identify bottom quark jets from top quark decay and reject background events. Given the relatively pure sample of bottom quark jets in tt ̄ dilepton final states, a new technique to measure in-situ the b-tagging efficiency is introduced that uses the distribution of the number of observed b-tagged jets. We present results with data collected at the ATLAS detector in 2010 with an integrated luminosity of 35 pb -1. The measured tt ̄ cross section is 176+22-21stat. +20-20 (syst.) +/- 6 (lum.) pb in the dilepton channel. We will also discuss the future prospects of this measurement.