Search For Anomalous Single Top Quark Production In Association With A Photon In Pp Collisions At U221a S
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Search For Anomalous Single Top Quark Production In Association With A Photon In Pp Collisions At U221a S
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Author :
language : en
Publisher:
Release Date : 2016
Search For Anomalous Single Top Quark Production In Association With A Photon In Pp Collisions At U221a S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
We found the results of a search for flavor changing neutral currents (FCNC) through single top quark production in association with a photon is presented. The study is based on proton-proton collisions at a center-of-mass energy of 8 TeV using data collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 19.8 fb-1. The search for t? events where t → Wb andW → ?n is conducted in final states with a muon, a photon, at least one hadronic jet with at most one being consistent with originating from a bottom quark, and missing transverse momentum. Furthermore, there was no evidence of single top quark production in association with a photon through a FCNC is observed. Upper limits at the 95% confidence level are set on the tug and tcg anomalous couplings and translated into upper limits on the branching fraction of the FCNC top quark decays: B(t → u?) 1.3 x 10sup-4/sup and B(t →c?) 1.7 x 10
Search For Anomalous Wtb Couplings In Single Top Quark Production In Pp Collisions At U221a S
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Author :
language : en
Publisher:
Release Date : 2012
Search For Anomalous Wtb Couplings In Single Top Quark Production In Pp Collisions At U221a S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with categories.
We present new direct constraints on a general Wtb interaction using data corresponding to an integrated luminosity of 5.4 fb-1 collected by the D0 detector at the Tevatron pp collider. The standard model provides a purely left-handed vector coupling at the Wtb vertex, while the most general, lowest dimension Lagrangian allows right-handed vector and left- or right-handed tensor couplings as well. We obtain precise limits on these anomalous couplings by comparing the data to the expectations from different assumptions on the Wtb coupling.
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
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Author :
language : en
Publisher:
Release Date : 2015
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 has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.
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.
Search For S Channel Single Top Quark Production In Pp Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2016
Search For S Channel Single Top Quark Production In Pp Collisions At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
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.
Evidence For Single Top Quark Production In The S Channel In Proton U2013 Proton Collisions At U221a S
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Author :
language : en
Publisher:
Release Date : 2016
Evidence For Single Top Quark Production In The S Channel In Proton U2013 Proton Collisions At U221a S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
This Letter presents evidence for single top-quark production in the s-channel using proton–proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS detector at the CERN Large Hadron Collider. The analysis is performed on events containing one isolated electron or muon, large missing transverse momentum and exactly two b-tagged jets in the final state. The analysed data set corresponds to an integrated luminosity of 20.3 fb-1. The signal is extracted using a maximum-likelihood fit of a discriminant which is based on the matrix element method and optimized in order to separate single-top-quark s-channel events from the main background contributions, which are top-quark pair production and W boson production in association with heavy-flavour jets. The measurement leads to an observed signal significance of 3.2 standard deviations and a measured cross-section of ?s = 4.8 ± 0.8(stat.)-1.3+1.6(syst.) pb, which is consistent with the Standard Model expectation. As a result, the expected significance for the analysis is 3.9 standard deviations.
Search For S Channel Single Top Quark Production In Pp Collisions At S
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Author :
language : en
Publisher:
Release Date : 2016
Search For S Channel Single Top Quark Production In Pp Collisions At S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
Observation Of Top Quark Pairs Produced In Association With A Vector Boson In Pp Collisions At U221a S
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Author :
language : en
Publisher:
Release Date : 2016
Observation Of Top Quark Pairs Produced In Association With A Vector Boson In Pp Collisions At U221a S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
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.
Cp Violating Anomalous Top Quark Coupling In P Bar P Collision At Sqrt S
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Author :
language : en
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Release Date : 2011
Cp Violating Anomalous Top Quark Coupling In P Bar P Collision At Sqrt S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
We conduct the first study of the T-odd correlations in tt events produced in p$\bar{p}$ collision at the Fermilab Tevatron collider that can be used to search for CP violation. We select events which have lepton+jets final states to identify t$\bar{t}$ events and measure counting asymmetries of several physics observables. Based on the result, we search the top quark anomalous couplings at the production vertex at the Tevatron. In addition, Geant4 development, photon identification, the discrimination of a single photon and a photon doublet from ?0 decay are discussed in this thesis.
Search For Anomalous Wtb Couplings And Flavour Changing Neutral Currents In T Channel Single Top Quark Production In Pp Collisions At S
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Author :
language : en
Publisher:
Release Date : 2016
Search For Anomalous Wtb Couplings And Flavour Changing Neutral Currents In T Channel Single Top Quark Production In Pp Collisions At S written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
Seeing A Single Top Quark
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Author : Harish Potti
language : en
Publisher:
Release Date : 2020
Seeing A Single Top Quark written by Harish Potti and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.
The top quark is the heaviest known elementary particle. With a coupling to the Higgs boson close to unity, the top quark plays a special role in electroweak symmetry breaking as well as in physics beyond the Standard Model. An accurate measurement of its properties can provide key information for understanding the physics at the TeV scale. In this dissertation, two measurements of the top quark properties are presented. The first part of this dissertation presents the first-ever ATLAS search for the associated production of a single top quark and a photon. This analysis is performed with 139 fb−1 of pp collision data collected by the ATLAS detector at the LHC at [square root symbol] s = 13 TeV. Only final states with exactly one lepton and at least one photon are considered in this analysis. In the second part, results from the combination of ATLAS searches for flavor changing neutral currents (FCNC) in t->Hq decays are presented. Four FCNC analyses, probing different Higgs decay modes, performed with 36.1 fb−1 of proton-proton collision data collected by the ATLAS detector in 2015-2016 are considered in the combination. They search for top-quark pair events in which one top quark decays into Wb and the other top quark decay into Hq