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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

2015
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Release : 2015
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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 . This book was released on 2015. 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.

Observation of Top Quark Pairs Produced in Association with a Vector Boson in Pp Collisions at {u221A}(s)

2016
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Release : 2016
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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 . This book was released on 2016. 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.

Measurement of the Top Quark Pair Production Cross Section in P Anti-p Collisions at {u221A}s

2006
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Release : 2006
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Book Synopsis Measurement of the Top Quark Pair Production Cross Section in P Anti-p Collisions at {u221A}s by :

Download or read book Measurement of the Top Quark Pair Production Cross Section in P Anti-p Collisions at {u221A}s written by . This book was released on 2006. Available in PDF, EPUB and Kindle. Book excerpt: The subject of this thesis is the measurement of the rate at which a top-antitop quark pair is produced in pp collisions at a center of mass energy of ps = 1:96 TeV. The data are collected with the D detector, a multi-purpose detector operating at the Fermilab Tevatron collider during Run II. A measurement of the top quark pair (t$\bar{t}$) production cross section ( ?t$\bar{t}$) in p$\bar{p}$ collisions at a center of mass energy of 1.96 TeV is presented. The measurement is based on data recorded by the D0 Detector at the Fermilab Tevatron Collider, and preselected in the e+jets (366 pb-1) and ?+jets (363 pb-1) channels. The cross section is extracted by applying a lifetime-tagging technique to the data, and yields ?t$\bar{t}$ = 6.96$+1.07\atop{-0.98}$(stat + syst) ± 0.45(lumi) pb; for a top quark mass mt =175 GeV, in good agreement with the Standard Model prediction.

Measurement of the Inclusive Top Quark Pair in Association with a Radiated Photon Production Cross Section in the Dilepton Channel for Pp Collisions at 8 TeV.

2017
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Release : 2017
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Book Synopsis Measurement of the Inclusive Top Quark Pair in Association with a Radiated Photon Production Cross Section in the Dilepton Channel for Pp Collisions at 8 TeV. by : Nik Berry

Download or read book Measurement of the Inclusive Top Quark Pair in Association with a Radiated Photon Production Cross Section in the Dilepton Channel for Pp Collisions at 8 TeV. written by Nik Berry. This book was released on 2017. Available in PDF, EPUB and Kindle. Book excerpt:

Measurement of the Top Quark Pair Production Cross Section in Pp Collisions at Sqrt(s)

2012
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Release : 2012
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Book Synopsis Measurement of the Top Quark Pair Production Cross Section in Pp Collisions at Sqrt(s) by :

Download or read book Measurement of the Top Quark Pair Production Cross Section in Pp Collisions at Sqrt(s) written by . This book was released on 2012. Available in PDF, EPUB and Kindle. Book excerpt: The top quark pair production cross section is measured in dilepton events with one electron or muon, and one hadronically decaying tau lepton from the decay t anti-t to (l nu(l)) (tau nu(tau)) b anti-b, where l can be either an electron or a muon. The data sample corresponds to an integrated luminosity of 2.0 inverse femtobarns for the electron channel and 2.2 inverse femtobarns for the muon channel, collected by the CMS detector at the LHC. This is the first measurement of the t anti-t cross section explicitly including tau leptons in proton-proton collisions at sqrt(s)=7 TeV. The measured value sigma(t anti-t) = 143 +/- 14 (stat.) +/- 22 (syst.) +/- 3 (lumi.) pb is consistent with the standard model predictions.

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