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Observation Of Top Quark Pairs Produced In Association With A W Or Z Boson In Pp Collisions At The Lhc
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Book Synopsis Observation of Top Quark Pairs Produced in Association with a W Or Z Boson in PP Collisions at the LHC by : Andrew Brinkerhoff
Download or read book Observation of Top Quark Pairs Produced in Association with a W Or Z Boson in PP Collisions at the LHC written by Andrew Brinkerhoff and published by . This book was released on 2015 with total page 209 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Observation of Top Quark Pairs Produced in Association with a Vector Boson in Pp Collisions at {u221A}(s) by :
Download or read book Observation of Top Quark Pairs Produced in Association with a Vector Boson in Pp Collisions at {u221A}(s) written by and published by . This book was released on 2016 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: Measurements of the cross sections for top quark pairs produced in association with a W or Z boson are presented, using 8 TeV pp collision data corresponding to an integrated luminosity of 19.5 fb-1, collected by the CMS experiment at the LHC. We found that final states are selected in which the associated W boson decays to a charged lepton and a neutrino or the Z boson decays to two charged leptons. Signal events are identified by matching reconstructed objects in the detector to specific final state particles from tt-W or tt-Z decays. The tt-W cross section is measured to be 382+117 -102 fb with a significance of 4.8 standard deviations from the background-only hypothesis. The tt-Z cross section is measured to be 242+65 -55 fb with a significance of 6.4 standard deviations from the background-only hypothesis. These measurements are used to set bounds on five anomalous dimension-six operators that would affect the tt-W and tt-Z cross sections.
Book Synopsis Search for the Higgs Boson Produced in Association with Top Quarks with the CMS Detector at the LHC by : Cristina Martin Perez
Download or read book Search for the Higgs Boson Produced in Association with Top Quarks with the CMS Detector at the LHC written by Cristina Martin Perez and published by Springer Nature. This book was released on 2022-02-09 with total page 291 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work, the interaction between the Higgs boson and the top quark is studied with the proton-proton collisions at 13 TeV provided by the LHC at the CMS detector at CERN (Geneva). At the LHC, these particles are produced simultaneously via the associate production of the Higgs boson with one top quark (tH process) or two top quarks (ttH process). Compared to many other possible outcomes of the proton-proton interactions, these processes are very rare, as the top quark and the Higgs boson are the heaviest elementary particles known. Hence, identifying them constitutes a significant experimental challenge. A high particle selection efficiency in the CMS detector is therefore crucial. At the core of this selection stands the Level-1 (L1) trigger system, a system that filters collision events to retain only those with potential interest for physics analysis. The selection of hadronically decaying τ leptons, expected from the Higgs boson decays, is especially demanding due to the large background arising from the QCD interactions. The first part of this thesis presents the optimization of the L1 τ algorithm in Run 2 (2016-2018) and Run 3 (2022-2024) of the LHC. It includes the development of a novel trigger concept for the High-Luminosity LHC, foreseen to start in 2027 and to deliver 5 times the current instantaneous luminosity. To this end, sophisticated algorithms based on machine learning approaches are used, facilitated by the increasingly modern technology and powerful computation of the trigger system. The second part of the work presents the search of the tH and ttH processes with the subsequent decays of the Higgs boson to pairs of τ lepton, W bosons or Z bosons, making use of the data recorded during Run 2. The presence of multiple particles in the final state, along with the low cross section of the processes, makes the search an ideal use case for multivariant discriminants that enhance the selectivity of the signals and reject the overwhelming background contributions. The discriminants presented are built using state-of-the-art machine learning techniques, able to capture the correlations amongst the processes involved, as well as the so-called Matrix Element Method (MEM), which combines the theoretical description of the processes with the detector resolution effects. The level of sophistication of the methods used, along with the unprecedented amount of collision data analyzed, result in the most stringent measurements of the tH and ttH cross sections up to date.
Book Synopsis Top Quark Physics at Hadron Colliders by : Arnulf Quadt
Download or read book Top Quark Physics at Hadron Colliders written by Arnulf Quadt and published by Springer Science & Business Media. This book was released on 2007-08-16 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Author :Anna Christine Henrichs Publisher :Springer Science & Business Media ISBN 13 :3319014870 Total Pages :231 pages Book Rating :4.3/5 (19 download)
Book Synopsis Top Quark Pair Production by : Anna Christine Henrichs
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.
Book Synopsis Measurement of Top Quark-antiquark Pair Production in Association with a W Or Z Boson in Pp Collisions at $\sqrt{s} by :
Download or read book Measurement of Top Quark-antiquark Pair Production in Association with a W Or Z Boson in Pp Collisions at $\sqrt{s} written by and published by . This book was released on 2014 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: A measurement of the cross section for the production of top quark-antiquark pairs (${\mathrm {t}}\overline{{\mathrm {t}}}$) in association with a vector boson V (W or Z) in proton-proton collisions at $\sqrt{s} = 8$ $\, \text {TeV}$ is presented. The results are based on a dataset corresponding to an integrated luminosity of 19.5 fb$^{-1}$ recorded with the CMS detector at the LHC. The measurement is performed in three leptonic (e and $\mu$) channels: a same-sign dilepton analysis targeting ${\mathrm {t}}\overline{{\mathrm {t}}} \mathrm {W} $ events, and trilepton and four-lepton analyses designed for ${\mathrm {t}}\overline{{\mathrm {t}}} {\mathrm {Z}} $ events. In the same-sign dilepton channel, the ${\mathrm {t}}\overline{{\mathrm {t}}} \mathrm {W} $ cross section is measured as $\sigma _{{\mathrm {t}}\overline{{\mathrm {t}}} \mathrm {W}} = 170 ^{+90-80}\, \text {(stat)} \pm 70\, \text {(syst)} \, \text {fb} $, corresponding to a significance of 1.6 standard deviations over the background-only hypothesis. Combining the trilepton and four-lepton channels, a direct measurement of the ${\mathrm {t}}\overline{{\mathrm {t}}} {\mathrm {Z}} $ cross section, $\sigma _{{\mathrm {t}}\overline{{\mathrm {t}}} {\mathrm {Z}}} = 200 ^{+80-70}\, \text {(stat)} ^{+40-30}\, \text {(syst)} \mathrm{fb}^{-1} $, is obtained with a significance of 3.1 standard deviations. The measured cross sections are compatible with standard model predictions within their experimental uncertainties. The inclusive ${\mathrm {t}}\overline{{\mathrm {t}}} {\mathrm {V}} $ process is observed with a significance of 3.7 standard deviations from the combination of all three leptonic channels.
Book Synopsis Top Quark, Heavy Flavor Physics And Symmetry Breaking, The - Proceedings Of The Xxiii International Meeting On Fundamental Physics by : Teresa Rodrigo
Download or read book Top Quark, Heavy Flavor Physics And Symmetry Breaking, The - Proceedings Of The Xxiii International Meeting On Fundamental Physics written by Teresa Rodrigo and published by World Scientific. This book was released on 1996-03-31 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt: This meeting discussed the experimental results and theoretical aspects in the field of high energy physics, with special reference to the top quark observation, heavy flavor physics and symmetry-breaking mechanisms. The major topics are developed in a series of course lectures.
Book Synopsis Higgs Boson Decays into a Pair of Bottom Quarks by : Cecilia Tosciri
Download or read book Higgs Boson Decays into a Pair of Bottom Quarks written by Cecilia Tosciri and published by Springer Nature. This book was released on 2021-10-22 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt: The discovery in 2012 of the Higgs boson at the Large Hadron Collider (LHC) represents a milestone for the Standard Model (SM) of particle physics. Most of the SM Higgs production and decay rates have been measured at the LHC with increased precision. However, despite its experimental success, the SM is known to be only an effective manifestation of a more fundamental description of nature. The scientific research at the LHC is strongly focused on extending the SM by searching, directly or indirectly, for indications of New Physics. The extensive physics program requires increasingly advanced computational and algorithmic techniques. In the last decades, Machine Learning (ML) methods have made a prominent appearance in the field of particle physics, and promise to address many challenges faced by the LHC. This thesis presents the analysis that led to the observation of the SM Higgs boson decay into pairs of bottom quarks. The analysis exploits the production of a Higgs boson associated with a vector boson whose signatures enable efficient triggering and powerful background reduction. The main strategy to maximise the signal sensitivity is based on a multivariate approach. The analysis is performed on a dataset corresponding to a luminosity of 79.8/fb collected by the ATLAS experiment during Run-2 at a centre-of-mass energy of 13 TeV. An excess of events over the expected background is found with an observed (expected) significance of 4.9 (4.3) standard deviation. A combination with results from other \Hbb searches provides an observed (expected) significance of 5.4 (5.5). The corresponding ratio between the signal yield and the SM expectation is 1.01 +- 0.12 (stat.)+ 0.16-0.15(syst.). The 'observation' analysis was further extended to provide a finer interpretation of the V H(H → bb) signal measurement. The cross sections for the VH production times the H → bb branching ratio have been measured in exclusive regions of phase space. These measurements are used to search for possible deviations from the SM with an effective field theory approach, based on anomalous couplings of the Higgs boson. The results of the cross-section measurements, as well as the constraining of the operators that affect the couplings of the Higgs boson to the vector boson and the bottom quarks, have been documented and discussed in this thesis. This thesis also describes a novel technique for the fast simulation of the forward calorimeter response, based on similarity search methods. Such techniques constitute a branch of ML and include clustering and indexing methods that enable quick and efficient searches for vectors similar to each other. The new simulation approach provides optimal results in terms of detector resolution response and reduces the computational requirements of a standard particles simulation.
Book Synopsis Observation of Single Top Quark with Associated Z Boson Production at the Large Hadron Collider Using the ATLAS Detector by : Dylan Frizzell
Download or read book Observation of Single Top Quark with Associated Z Boson Production at the Large Hadron Collider Using the ATLAS Detector written by Dylan Frizzell and published by . This book was released on 2019 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Search for Higgs Boson Pair Production in the bb̅ τ+ τ- Decay Channel by : Luca Cadamuro
Download or read book Search for Higgs Boson Pair Production in the bb̅ τ+ τ- Decay Channel written by Luca Cadamuro and published by Springer. This book was released on 2018-12-06 with total page 273 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents innovative contributions to the CMS experiment in the new trigger system for the restart of the LHC collisions in Run II, as well as original analysis methods and important results that led to official publications of the Collaboration. The author's novel reconstruction algorithms, deployed on the Field-Programmable Gate Arrays of the new CMS trigger architecture, have brought a gain of over a factor 2 in efficiency for the identification of tau leptons, with a very significant impact on important H boson measurements, such as its decays to tau lepton pairs and the search for H boson pair production. He also describes a novel analysis of HH → bb tautau, a high priority physics topic in a difficult channel. The original strategy, optimisation of event categories, and the control of the background have made the result one of the most sensitive concerning the self-coupling of the Higgs boson among all possible channels at the LHC.
Book Synopsis Observation of Top-quark Pair Production in Association with a Photon and Measurement of the Tt{u00AF}? Production Cross Section in pp Collisions at {u221A}s by :
Download or read book Observation of Top-quark Pair Production in Association with a Photon and Measurement of the Tt{u00AF}? Production Cross Section in pp Collisions at {u221A}s written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A search is performed for top-quark pairs (tt¯) produced together with a photon (?) with transverse energy greater than 20 GeV using a sample of tt¯ candidate events in final states with jets, missing transverse momentum, and one isolated electron or muon. The data set used corresponds to an integrated luminosity of 4.59 fb−1 of proton-proton collisions at a center-of-mass energy of 7 TeV recorded by the ATLAS detector at the CERN Large Hadron Collider. In total, 140 and 222 tt¯? candidate events are observed in the electron and muon channels, to be compared to the expectation of 79 ± 26 and 120 ± 39 non-tt¯? background events, respectively. The production of tt¯? events is observed with a significance of 5.3 standard deviations away from the null hypothesis. The tt¯? production cross section times the branching ratio (BR) of the single-lepton decay channel is measured in a fiducial kinematic region within the ATLAS acceptance. The measured value is ?fidtt¯? × BR = 63 ± 8(stat)+17–13(syst) ± 1(lumi) fb per lepton flavor, in good agreement with the leading-order theoretical calculation normalized to the next-to-leading-order theoretical prediction of 48 ± 10 fb.
Book Synopsis A Study of Top Quark Pair Using CMS Data by : Muhammad Gul
Download or read book A Study of Top Quark Pair Using CMS Data written by Muhammad Gul and published by LAP Lambert Academic Publishing. This book was released on 2013 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Large Hadron (LHC) is the highest-energy particle collider ever made. It was built by the European Organization for Nuclear Research (CERN) from 1998 to 2008, in collaboration with around 100 countries. The LHC lies in a tunnel 27 km in circumference and 100 m underground on Franco-Swiss border near Geneva, Switzerland. The Compact Muon Solenoid (CMS) is one of the general-purpose experiment at the LHC. It has recently discovered the Higgs Boson, the only missing piece of Standard Model (SM). LHC is also a Top Quark factory. Top Quark is the heaviest of all known elementary particles and has very short life time. It couples strongly to Higgs Boson and sensitive to New Physics. Therefore the study of Top Quark properties is very important. In this work different parameters of Top Quark, such as Mass, Transverse momentum, Energy etc, are studied.
Book Synopsis Associated Production of W + Charm in 13 TeV Proton-Proton Collisions Measured with CMS and Determination of the Strange Quark Content of the Proton by : Svenja Karen Pflitsch
Download or read book Associated Production of W + Charm in 13 TeV Proton-Proton Collisions Measured with CMS and Determination of the Strange Quark Content of the Proton written by Svenja Karen Pflitsch and published by Springer Nature. This book was released on 2020-08-18 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Search for W' Boson with Boosted and Hadronic Top-quark Final State in Pp Collisions at 8́(s by : Kuan-Yu Lin
Download or read book Search for W' Boson with Boosted and Hadronic Top-quark Final State in Pp Collisions at 8́(s written by Kuan-Yu Lin and published by . This book was released on 2021 with total page 181 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Single Top Quark Production and Decay in Hadron Collision at Next-to-leading Order by : Qinghong Cao
Download or read book Single Top Quark Production and Decay in Hadron Collision at Next-to-leading Order written by Qinghong Cao and published by . This book was released on 2005 with total page 466 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Search for Top-squark Pairs Decaying Into Higgs Or Z Bosons in Pp Collisions at {u221A}s by :
Download or read book Search for Top-squark Pairs Decaying Into Higgs Or Z Bosons in Pp Collisions at {u221A}s written by and published by . This book was released on 2014 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our search for supersymmetry through the direct pair production of top squarks, with Higgs (H) or Z bosons in the decay chain, is performed using a data sample of proton–proton collisions at √s= 8TeV collected in 2012 with the CMS detector at the LHC. The sample corresponds to an integrated luminosity of 19.5 fb-1. The search is performed using a selection of events containing leptons and bottom-quark jets. No evidence for a significant excess of events over the standard model background prediction is observed. The results are interpreted in the context of simplified supersymmetric models with pair production of a heavier top-squark mass eigenstate t̃/sup2 source decaying to a lighter top-squark mass eigenstate t̃/sup2 via either t̃/sup2 → Ht̃/sup1 or tsup̃/sup2 →Ztsup̃/sup1, followed in both cases by tsup̃/sup1→ t?sup0̃1, where ?sup0̃1 source is an undetected, stable, lightest supersymmetric particle. The interpretation is performed in the region where the mass difference between the tsup̃/sup1 and ?sup0̃1 states is approximately equal to the top-quark mass (mt1-msup?01≃mt), which is not probed by searches for direct tsup̃/sup1 squark pair production. This analysis excludes top squarks with mass mt1 575 GeVand msubt2
Book Synopsis Associated Production of a Top Quark and a Z Boson in Pp Collisions at √s by : Irina Antonela Cioară
Download or read book Associated Production of a Top Quark and a Z Boson in Pp Collisions at √s written by Irina Antonela Cioară and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
