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 ATLAS collaboration

doi:10.1140/epjc/s10052-014-3109-7

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 ATLAS collaboration

Department of Physics

Research output: Contribution to journal › Article › peer-review

168 Scopus citations

Abstract

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 t₁ with masses close to the top quark mass, decaying via t₁ → t χ⁰₁ to predominantly right-handed top quarks and a light neutralino χ⁰₁, the lightest supersymmet-ric particle. Top squarks with masses between the top quark mass and 177 GeV are excluded at the 95 % confidence level.

Original language	English (US)
Article number	3109
Journal	European Physical Journal C
Volume	74
Issue number	10
DOIs	https://doi.org/10.1140/epjc/s10052-014-3109-7
State	Published - Oct 21 2014

ASJC Scopus subject areas

Engineering (miscellaneous)
Physics and Astronomy (miscellaneous)

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10.1140/epjc/s10052-014-3109-7

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@article{92d778f86bfb4489bbb8d9df28cf2fed,

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",

abstract = "The inclusive top quark pair (tt) production cross-section σtt 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 σtt 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: σtt = 182.9 ± 3.1 ± 4.2 ± 3.6 ± 3.3 pb (√s = 7 TeV) and σtt = 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 mpolet giving a result of mpolet = 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 t1 with masses close to the top quark mass, decaying via t1 → t χ01 to predominantly right-handed top quarks and a light neutralino χ01, the lightest supersymmet-ric particle. Top squarks with masses between the top quark mass and 177 GeV are excluded at the 95 % confidence level.",

author = "{The ATLAS collaboration} and G. Aad and B. Abbott and J. Abdallah and {Abdel Khalek}, S. and O. Abdinov and R. Aben and B. Abi and M. Abolins and Abouzeid, {O. S.} and H. Abramowicz and H. Abreu and R. Abreu and Y. Abulaiti and Acharya, {B. S.} and L. Adamczyk and Adams, {D. L.} and J. Adelman and S. Adomeit and T. Adye and T. Agatonovic-Jovin and Aguilar-Saavedra, {J. A.} and M. Agustoni and Ahlen, {S. P.} and F. Ahmadov and G. Aielli and H. Akerstedt and {\AA}kesson, {T. P.A.} and G. Akimoto and Akimov, {A. V.} and Alberghi, {G. L.} and J. Albert and S. Albrand and {Alconada Verzini}, {M. J.} and M. Aleksa and Aleksandrov, {I. N.} and C. Alexa and G. Alexander and G. Alexandre and T. Alexopoulos and M. Alhroob and G. Alimonti and L. Alio and J. Alison and Allbrooke, {B. M.M.} and Allison, {L. J.} and Allport, {P. P.} and J. Almond and A. Aloisio and A. Alonso and Rudolph, {M. S.}",

note = "Publisher Copyright: {\textcopyright} CERN for the benefit of the ATLAS collaboration 2014.",

year = "2014",

month = oct,

day = "21",

doi = "10.1140/epjc/s10052-014-3109-7",

language = "English (US)",

volume = "74",

journal = "European Physical Journal C",

issn = "1434-6044",

publisher = "Springer New York",

number = "10",

}

TY - JOUR

T1 - 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

AU - The ATLAS collaboration

AU - Aad, G.

AU - Abbott, B.

AU - Abdallah, J.

AU - Abdel Khalek, S.

AU - Abdinov, O.

AU - Aben, R.

AU - Abi, B.

AU - Abolins, M.

AU - Abouzeid, O. S.

AU - Abramowicz, H.

AU - Abreu, H.

AU - Abreu, R.

AU - Abulaiti, Y.

AU - Acharya, B. S.

AU - Adamczyk, L.

AU - Adams, D. L.

AU - Adelman, J.

AU - Adomeit, S.

AU - Adye, T.

AU - Agatonovic-Jovin, T.

AU - Aguilar-Saavedra, J. A.

AU - Agustoni, M.

AU - Ahlen, S. P.

AU - Ahmadov, F.

AU - Aielli, G.

AU - Akerstedt, H.

AU - Åkesson, T. P.A.

AU - Akimoto, G.

AU - Akimov, A. V.

AU - Alberghi, G. L.

AU - Albert, J.

AU - Albrand, S.

AU - Alconada Verzini, M. J.

AU - Aleksa, M.

AU - Aleksandrov, I. N.

AU - Alexa, C.

AU - Alexander, G.

AU - Alexandre, G.

AU - Alexopoulos, T.

AU - Alhroob, M.

AU - Alimonti, G.

AU - Alio, L.

AU - Alison, J.

AU - Allbrooke, B. M.M.

AU - Allison, L. J.

AU - Allport, P. P.

AU - Almond, J.

AU - Aloisio, A.

AU - Alonso, A.

AU - Rudolph, M. S.

PY - 2014/10/21

Y1 - 2014/10/21

N2 - The inclusive top quark pair (tt) production cross-section σtt 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 σtt 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: σtt = 182.9 ± 3.1 ± 4.2 ± 3.6 ± 3.3 pb (√s = 7 TeV) and σtt = 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 mpolet giving a result of mpolet = 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 t1 with masses close to the top quark mass, decaying via t1 → t χ01 to predominantly right-handed top quarks and a light neutralino χ01, the lightest supersymmet-ric particle. Top squarks with masses between the top quark mass and 177 GeV are excluded at the 95 % confidence level.

AB - The inclusive top quark pair (tt) production cross-section σtt 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 σtt 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: σtt = 182.9 ± 3.1 ± 4.2 ± 3.6 ± 3.3 pb (√s = 7 TeV) and σtt = 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 mpolet giving a result of mpolet = 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 t1 with masses close to the top quark mass, decaying via t1 → t χ01 to predominantly right-handed top quarks and a light neutralino χ01, the lightest supersymmet-ric particle. Top squarks with masses between the top quark mass and 177 GeV are excluded at the 95 % confidence level.

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SN - 1434-6044

VL - 74

JO - European Physical Journal C

JF - European Physical Journal C

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ER -

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

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