Download or read book Top Quark Pair Production written by Anna Christine Henrichs and published by Springer Science & Business Media. This book was released on 2013-10-04 with total page 231 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Measurements of Top Quark Pair Production Cross sections with the ATLAS Experiment written by Abigail O'Rourke and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Precision Measurements of the Top Quark Pair Production Cross Section in the Single Lepton Channel with the ATLAS Experiment written by Anna Christine Henrichs and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurement of the Top Quark Pair Production Cross Section with the ATLAS Experiment at s written by Volker Vorwerk and published by . This book was released on 2011 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Simultaneous Measurement of the Top Quark Pair Production Cross section and Rb in the ATLAS Experiment written by Jordi Nadal Serrano and published by . This book was released on 2012* with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurements of Differential Cross sections in Top quark Pair Events with a High Transverse Momentum Top Quark and Limits on Beyond the Standard Model Contributions to Top quark Pair Production with the ATLAS Detector at square Root s written by [Study Group] ATLAS Collaboration CERN and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Top Quark Pair Production Cross Sections and Calibration of the Top Quark Monte Carlo Mass written by Jan Kieseler and published by Springer. This book was released on 2016-06-15 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Cross section Measurements of Top quark Pair Production in Association with a Hard Photon at 13 TeV with the ATLAS Detector written by Knut Zoch and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: 25 years after the top quark's discovery, the Large Hadron Collider at CERN produces proton-proton collision data on unprecedented scales at unprecedented energies - and has heralded an era of top-quark precision measurements. The production of a top-quark pair in association with a photon ($t bar{t} gamma$) gives access to the electromagnetic top-photon coupling, one of the fundamental properties of the top quark. Various extensions of the Standard Model predict modifications of the coupling strength or structure, and deviations from the Standard Model prediction of the $t bar{t} gamma$ pr...
Download or read book Measurement of the Top Quark Pair Production Cross Section with ATLAS Detector written by Babak Abi and published by . This book was released on 2012 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Novel Approach to Precision Measurements of the Top Quark antiquark Pair Production Cross Section with the ATLAS Experiment written by Clemens Gregor Lange and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurements of the Top Quark Pair Production Cross Section and Branching Ratio to a W boson and Bottom Quark Using the Semi leptonic and Dilepton Final States with the ATLAS Detector at the LHC written by Robert E. Calkins and published by . This book was released on 2012 with total page 241 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract : In the Standard Model, the top quark plays a unique role as the heaviest known fundamental particle and as a quark that decays before it is able to hadronize. Top quarks are expected to decay to a W-boson and a b-quark nearly 100% of the time. If the branching ratio of t → Wb is lower than one, the distribution of the number of b-tagged jets will shift to lower multiplicities. A simultaneous likelihood fit to the number of b-tagged jets distributions in the lepton+jets and dilepton channels is performed on 4.7 fb−1 of data collected by the ATLAS detector to extract both the branching ratio and the tt ̄ cross section. The branching ratio of t → Wb, R, is measured to be 1.06±0.11, which is consistent with the Standard Model value. This is the first measurement of the t → Wb branching ratio performed with the ATLAS detector using both the lepton+jets and dilepton channels at the LHC. The tt ̄ cross section is measured to be [special characters omitted] pb, which agrees with NNLO predictions.
Download or read book Cross Section Measurement and Search for New Physics with Top Quark Pair Events Involving a Tau Lepton in ATLAS written by Jennifer Lynn Godfrey and published by . This book was released on 2013 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt: In 2011, the ATLAS detector recorded an integrated luminosity of over 5 fb−1 of proton-proton collisions delivered by the LHC at a centre-of-mass square root of s = 7 TeV. The first of two analyses is a test of the standard model and the world's most precise measurement of the top quark pair production cross section for final states which include a hadronically decaying tau lepton. The second analysis uses the same dataset to search for a charged Higgs boson, also resulting in the world's best limits for the search channel. In the cross section measurement, 2.1 fb−1 of ATLAS proton-proton collision data is used to measure the top quark pair production cross section in events containing an isolated electron or muon and a tau lepton decaying hadronically. After initial event requirements, the leading background comes from top quark pairs with jets faking tau leptons. A fit to a tau lepton identification variable is used to determine the signal yield. The measured cross section, [sigma][subscript{tt̄}] 186±13(stat.)±2019(syst.)±7(lumi.)pb, is in good agreement with the standard model prediction. Several extensions to the standard model predict the existence of at least one charged Higgs boson, H[superscript ±]. According to these extensions, the top quark can decay into a bottom quark and a light charged Higgs boson in addition to the standard model decay to a bottom quark and aW boson. In the second analysis, event yield ratios between different final states are measured using 4.6 fb−1 of ATLAS data. This is compared to simulation to search for a violation of lepton universality. This ratio-based method reduces the impact of systematic uncertainties in the analysis. No significant deviations from the standard model predictions are observed. With the assumption that the charged Higgs boson branching ratio to a tau lepton and a neutrino is 100%, upper limits in the range 3.2%-4.4% can be placed on the top quark to charged Higgs branching ratio for 90 less than or equal to m[subscript {H[superscript ±]}] less than or equal to 140 GeV. After combination with results from a search for charged Higgs bosons in tt̄ decays using the thad+jets final state, upper limits on this branching ratio can be set in the range 0.8%-3.4%, for 90 less than or equal to m[subscript {H[superscript ±]}] less than or equal to 140 GeV.
Download or read book Measurement of the Top Quark Pair Production Cross Section and an In situ B tagging Efficiency Calibration with ATLAS in Pp Collisions at s written by Bin Guo and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present a measurement of the top anti-top quark (ttbar)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 ttbar 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 ttbar cross section is 176 +22/-21 (stat.) ± 20 (syst.) ± 6 (lum.) pb in the dilepton channel. We will also discuss the future prospects of this measurement.
Download or read book Measurement of the Top Quark Pair Production Cross Section With ATLAS in Pp Collisions at sqrt s written by and published by . This book was released on 2013 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurement of the Production Cross section of a Single Top Quark in Association with a W Boson at 8 TeV with the ATLAS Experiment written by and published by . This book was released on 2016 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Differentiating Top quark Photon Coupling Inclusive and Differential Cross section Measurements of Top quark Pair Production in Association with a Photon in the Single Lepton Channel in Pp Collisions Data at s 8TeV with the ATLAS Experiment written by Naim Bora Atlay and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book ATLAS Measurements of the Higgs Boson Coupling to the Top Quark in the Higgs to Diphoton Decay Channel written by Jennet Elizabeth Dickinson and published by Springer Nature. This book was released on 2021-11-16 with total page 233 pages. Available in PDF, EPUB and Kindle. Book excerpt: During Run 2 of the Large Hadron Collider, the ATLAS experiment recorded proton-proton collision events at 13 TeV, the highest energy ever achieved in a collider. Analysis of this dataset has provided new opportunities for precision measurements of the Higgs boson, including its interaction with the top quark. The Higgs-top coupling can be directly probed through the production of a Higgs boson in association with a top-antitop quark pair (ttH). The Higgs to diphoton decay channel is among the most sensitive for ttH measurements due to the excellent diphoton mass resolution of the ATLAS detector and the clean signature of this decay. Event selection criteria were developed using novel Machine Learning techniques to target ttH events, yielding a precise measurement of the ttH cross section in the diphoton channel and a 6.3 $\sigma$ observation of the ttH process in combination with other decay channels, as well as stringent limits on CP violation in the Higgs-top coupling.
