Measurement of the tt production cross-section using eµ events with b-tagged jets in pp collisions at √s = 7 and 8 TeV with the ATLAS detector

The inclusive top quark pair (tt) production cross-section σ tt has been measured in proton–proton collisions at √s = 7 TeV and√s = 8 TeV with the ATLAS experiment at the LHC, using tt events with an opposite-charge eμ pair in the final state. The measurement was performed with the 2011 7 TeV datase...

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Autor principal: Aad, G.
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Acceso en línea:http://hdl.handle.net/20.500.12110/paper_14346044_v74_n10_p_Aad
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
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spelling todo:paper_14346044_v74_n10_p_Aad2023-10-03T16:14:56Z Measurement of the tt production cross-section using eµ events with b-tagged jets in pp collisions at √s = 7 and 8 TeV with the ATLAS detector Aad, G. The inclusive top quark pair (tt) production cross-section σ tt has been measured in proton–proton collisions at √s = 7 TeV and√s = 8 TeV with the ATLAS experiment at the LHC, using tt events with an opposite-charge eμ pair in the final state. The measurement was performed with the 2011 7 TeV dataset corresponding to an integrated luminosity of 4.6 fb −1 and the 2012 8 TeV dataset of 20.3 fb −1 . The numbers of events with exactly one and exactly two b-tagged jets were counted and used to simultaneously determine σ tt and the efficiency to reconstruct and b-tag a jet from a top quark decay, thereby minimising the associated systematic uncertainties. The cross-section was measured to be: σ tt = 182.9 ± 3.1 ± 4.2 ± 3.6 ± 3.3 pb (√s = 7 TeV) and σ tt = 242.4 ± 1.7 ± 5.5 ± 7.5 ± 4.2 pb (√s = 8 TeV), where the four uncertainties arise from data statistics, experimental and theoretical systematic effects, knowledge of the integrated luminosity and of the LHC beam energy. The results are consistent with recent theoretical QCD calculations at next-to-next-to-leading order. Fiducial measurements corresponding to the experimental acceptance of the leptons are also reported, together with the ratio of cross-sections measured at the two centre-of-mass energies. The inclusive cross-section results were used to determine the top quark pole mass via the dependence of the theoretically predicted cross-section on m pole t giving a result of m pole t = 172.9 +2.5 −2.6 GeV. By looking for an excess of tt production with respect to the QCD prediction, the results were also used to place limits on the pair-production of supersymmetric top squarks t 1 with masses close to the top quark mass, decaying via t 1 → t χ 0 1 to predominantly right-handed top quarks and a light neutralino χ 0 1 , the lightest supersymmet-ric particle. Top squarks with masses between the top quark mass and 177 GeV are excluded at the 95 % confidence level. © CERN for the benefit of the ATLAS collaboration 2014. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_14346044_v74_n10_p_Aad
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
description The inclusive top quark pair (tt) production cross-section σ tt has been measured in proton–proton collisions at √s = 7 TeV and√s = 8 TeV with the ATLAS experiment at the LHC, using tt events with an opposite-charge eμ pair in the final state. The measurement was performed with the 2011 7 TeV dataset corresponding to an integrated luminosity of 4.6 fb −1 and the 2012 8 TeV dataset of 20.3 fb −1 . The numbers of events with exactly one and exactly two b-tagged jets were counted and used to simultaneously determine σ tt and the efficiency to reconstruct and b-tag a jet from a top quark decay, thereby minimising the associated systematic uncertainties. The cross-section was measured to be: σ tt = 182.9 ± 3.1 ± 4.2 ± 3.6 ± 3.3 pb (√s = 7 TeV) and σ tt = 242.4 ± 1.7 ± 5.5 ± 7.5 ± 4.2 pb (√s = 8 TeV), where the four uncertainties arise from data statistics, experimental and theoretical systematic effects, knowledge of the integrated luminosity and of the LHC beam energy. The results are consistent with recent theoretical QCD calculations at next-to-next-to-leading order. Fiducial measurements corresponding to the experimental acceptance of the leptons are also reported, together with the ratio of cross-sections measured at the two centre-of-mass energies. The inclusive cross-section results were used to determine the top quark pole mass via the dependence of the theoretically predicted cross-section on m pole t giving a result of m pole t = 172.9 +2.5 −2.6 GeV. By looking for an excess of tt production with respect to the QCD prediction, the results were also used to place limits on the pair-production of supersymmetric top squarks t 1 with masses close to the top quark mass, decaying via t 1 → t χ 0 1 to predominantly right-handed top quarks and a light neutralino χ 0 1 , the lightest supersymmet-ric particle. Top squarks with masses between the top quark mass and 177 GeV are excluded at the 95 % confidence level. © CERN for the benefit of the ATLAS collaboration 2014.
format JOUR
author Aad, G.
spellingShingle Aad, G.
Measurement of the tt production cross-section using eµ events with b-tagged jets in pp collisions at √s = 7 and 8 TeV with the ATLAS detector
author_facet Aad, G.
author_sort Aad, G.
title Measurement of the tt production cross-section using eµ events with b-tagged jets in pp collisions at √s = 7 and 8 TeV with the ATLAS detector
title_short Measurement of the tt production cross-section using eµ events with b-tagged jets in pp collisions at √s = 7 and 8 TeV with the ATLAS detector
title_full Measurement of the tt production cross-section using eµ events with b-tagged jets in pp collisions at √s = 7 and 8 TeV with the ATLAS detector
title_fullStr Measurement of the tt production cross-section using eµ events with b-tagged jets in pp collisions at √s = 7 and 8 TeV with the ATLAS detector
title_full_unstemmed Measurement of the tt production cross-section using eµ events with b-tagged jets in pp collisions at √s = 7 and 8 TeV with the ATLAS detector
title_sort measurement of the tt production cross-section using eµ events with b-tagged jets in pp collisions at √s = 7 and 8 tev with the atlas detector
url http://hdl.handle.net/20.500.12110/paper_14346044_v74_n10_p_Aad
work_keys_str_mv AT aadg measurementofthettproductioncrosssectionusingeμeventswithbtaggedjetsinppcollisionsats7and8tevwiththeatlasdetector
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