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
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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
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Author : Universitat de València. Facultat de Física
language : en
Publisher:
Release Date : 2014
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 written by Universitat de València. Facultat de Física and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014 with categories.
Cross Section Measurement And Search For New Physics With Top Quark Pair Events Involving A Tau Lepton In Atlas
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Author : Jennifer Lynn Godfrey
language : en
Publisher:
Release Date : 2013
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 has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with Higgs bosons categories.
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.
Measurement Of The Top Pair Production Cross Section In 8 Tev Proton Proton Collisions Using Kinematic Information In The Lepton Plus Jets Final State With Atlas
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Author :
language : en
Publisher:
Release Date : 2015
Measurement Of The Top Pair Production Cross Section In 8 Tev Proton Proton Collisions Using Kinematic Information In The Lepton Plus Jets Final State With Atlas 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.
Measurement Of The Top Quark Pair Production Cross Section In Pp Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2012
Measurement Of The Top Quark Pair Production Cross Section 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 2012 with categories.
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.
First Measurement Of The Cross Section For Top Quark Pair Production In Proton Proton Collisions At Sqrt S
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Author :
language : en
Publisher:
Release Date : 2011
First Measurement Of The Cross Section For Top Quark Pair Production In Proton Proton 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 2011 with categories.
The first measurement of the cross section for top-quark pair production in pp collisions at the LHC at center-of-mass energy sqrt(s)= 7 TeV has been performed using 3.1 {\pm} 0.3 inverse pb of data recorded by the CMS detector. This result utilizes the final state with two isolated, highly energetic charged leptons, large missing transverse energy, and two or more jets. Backgrounds from Drell-Yan and non-W/Z boson production are estimated from data. Eleven events are observed in the data with 2.1 {\pm} 1.0 events expected from background. The measured cross section is 194 {\pm} 72 (stat.) {\pm} 24 (syst.) {\pm} 21 (lumi.) pb, consistent with next-to-leading order predictions.
First Measurement Of The Top Quark Pair Production Cross Section In Proton Proton Collisions At The Center Of Mass Energy Of 7 Tev
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Author : Puneeth D. Kalavase
language : en
Publisher:
Release Date : 2011
First Measurement Of The Top Quark Pair Production Cross Section In Proton Proton Collisions At The Center Of Mass Energy Of 7 Tev written by Puneeth D. Kalavase 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.
The first measurement of the cross section for top-quark pair production in proton-proton collisions at the Large Hadron Collider at center-of-mass energy of 7 TeV has been performed using a data sample corresponding to an integrated luminosity of 3 pb-1 recorded by the CMS detector. This result utilizes the final state with two isolated, highly energetic charged leptons, large missing transverse energy, and two or more jets. Backgrounds from Drell-Yan and non-W/Z boson production are estimated from data. Eleven events are observed in the data with 2.1+/-1.0 events expected from background. The measured cross section is 194+/-72 (statistical) +/-24 (systematic) +/-21 (luminosity) pb. The result is consistent with next-to-leading order theoretical predictions.
Measurement Of The Top Quark Pair Production Cross Section And An In Situ B Tagging Efficiency Calibration With Atlas In Pp Collisions At S
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Author : Bin Guo
language : en
Publisher:
Release Date : 2012
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 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 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.
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.
Measurement Of The Top Pair Production Cross Section In 8 Tev Proton Proton Collisions Using Kinematic Information In The Lepton Jets Final State With Atlas
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Author :
language : en
Publisher:
Release Date : 2015
Measurement Of The Top Pair Production Cross Section In 8 Tev Proton Proton Collisions Using Kinematic Information In The Lepton Jets Final State With Atlas 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.
Top Quark Pair Production
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Author : Anna Christine Henrichs
language : en
Publisher:
Release Date : 2013-10-31
Top Quark Pair Production written by Anna Christine Henrichs and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-10-31 with categories.