Search for the Standard Model Higgs boson produced in association with top quarks and decaying into bb in pp collisions at √s = 8 TeV with the ATLAS detector

The ATLAS Collaboration

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    Abstract

    A search for the Standard Model Higgs boson produced in association with a top-quark pair, $$t\bar{t}H$$tt¯H, is presented. The analysis uses 20.3 fb<sup>−1</sup> of pp collision data at $$\sqrt{s}=8{{\,\mathrm TeV}}$$s=8TeV, collected with the ATLAS detector at the Large Hadron Collider during 2012. The search is designed for the $$H \rightarrow b\bar{b}$$H→bb¯ decay mode and uses events containing one or two electrons or muons. In order to improve the sensitivity of the search, events are categorised according to their jet and b-tagged jet multiplicities. A neural network is used to discriminate between signal and background events, the latter being dominated by $$t\bar{t}$$tt¯+jets production. In the single-lepton channel, variables calculated using a matrix element method are included as inputs to the neural network to improve discrimination of the irreducible $$t\bar{t}{+}b\bar{b}$$tt¯+bb¯ background. No significant excess of events above the background expectation is found and an observed (expected) limit of 3.4 (2.2) times the Standard Model cross section is obtained at 95 % confidence level. The ratio of the measured $${t\bar{t}H}$$tt¯H signal cross section to the Standard Model expectation is found to be $$\mu = 1.5 \pm 1.1$$μ=1.5±1.1 assuming a Higgs boson mass of 125$${{\,\mathrm GeV\,}}$$GeV.

    Original languageEnglish
    Article number349
    JournalEuropean Physical Journal C
    Volume75
    Issue number7
    DOIs
    Publication statusPublished - 2015 Jul 30

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    Bosons
    Higgs bosons
    quarks
    Detectors
    collisions
    detectors
    Neural networks
    Colliding beam accelerators
    cross sections
    discrimination
    leptons
    muons
    confidence
    Electrons
    sensitivity
    decay
    matrices
    electrons

    ASJC Scopus subject areas

    • Physics and Astronomy (miscellaneous)
    • Engineering (miscellaneous)

    Cite this

    @article{e05cd15cad994bb085572a60136ff596,
    title = "Search for the Standard Model Higgs boson produced in association with top quarks and decaying into bb in pp collisions at √s = 8 TeV with the ATLAS detector",
    abstract = "A search for the Standard Model Higgs boson produced in association with a top-quark pair, $$t\bar{t}H$$tt¯H, is presented. The analysis uses 20.3 fb−1 of pp collision data at $$\sqrt{s}=8{{\,\mathrm TeV}}$$s=8TeV, collected with the ATLAS detector at the Large Hadron Collider during 2012. The search is designed for the $$H \rightarrow b\bar{b}$$H→bb¯ decay mode and uses events containing one or two electrons or muons. In order to improve the sensitivity of the search, events are categorised according to their jet and b-tagged jet multiplicities. A neural network is used to discriminate between signal and background events, the latter being dominated by $$t\bar{t}$$tt¯+jets production. In the single-lepton channel, variables calculated using a matrix element method are included as inputs to the neural network to improve discrimination of the irreducible $$t\bar{t}{+}b\bar{b}$$tt¯+bb¯ background. No significant excess of events above the background expectation is found and an observed (expected) limit of 3.4 (2.2) times the Standard Model cross section is obtained at 95 {\%} confidence level. The ratio of the measured $${t\bar{t}H}$$tt¯H signal cross section to the Standard Model expectation is found to be $$\mu = 1.5 \pm 1.1$$μ=1.5±1.1 assuming a Higgs boson mass of 125$${{\,\mathrm GeV\,}}$$GeV.",
    author = "{The ATLAS Collaboration} and G. Aad and B. Abbott and J. Abdallah and O. Abdinov and R. Aben 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 Affolder, {A. A.} 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 T. Alexopoulos and M. Alhroob and G. Alimonti and L. Alio and J. Alison and Alkire, {S. P.} and Allbrooke, {B. M M} and Allport, {P. P.} and A. Aloisio and A. Alonso and F. Alonso and P. Iengo and Masahiro Morinaga and Kohei Yorita",
    year = "2015",
    month = "7",
    day = "30",
    doi = "10.1140/epjc/s10052-015-3543-1",
    language = "English",
    volume = "75",
    journal = "European Physical Journal C",
    issn = "1434-6044",
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    TY - JOUR

    T1 - Search for the Standard Model Higgs boson produced in association with top quarks and decaying into bb in pp collisions at √s = 8 TeV with the ATLAS detector

    AU - The ATLAS Collaboration

    AU - Aad, G.

    AU - Abbott, B.

    AU - Abdallah, J.

    AU - Abdinov, O.

    AU - Aben, R.

    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 - Affolder, A. A.

    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 - Alexopoulos, T.

    AU - Alhroob, M.

    AU - Alimonti, G.

    AU - Alio, L.

    AU - Alison, J.

    AU - Alkire, S. P.

    AU - Allbrooke, B. M M

    AU - Allport, P. P.

    AU - Aloisio, A.

    AU - Alonso, A.

    AU - Alonso, F.

    AU - Iengo, P.

    AU - Morinaga, Masahiro

    AU - Yorita, Kohei

    PY - 2015/7/30

    Y1 - 2015/7/30

    N2 - A search for the Standard Model Higgs boson produced in association with a top-quark pair, $$t\bar{t}H$$tt¯H, is presented. The analysis uses 20.3 fb−1 of pp collision data at $$\sqrt{s}=8{{\,\mathrm TeV}}$$s=8TeV, collected with the ATLAS detector at the Large Hadron Collider during 2012. The search is designed for the $$H \rightarrow b\bar{b}$$H→bb¯ decay mode and uses events containing one or two electrons or muons. In order to improve the sensitivity of the search, events are categorised according to their jet and b-tagged jet multiplicities. A neural network is used to discriminate between signal and background events, the latter being dominated by $$t\bar{t}$$tt¯+jets production. In the single-lepton channel, variables calculated using a matrix element method are included as inputs to the neural network to improve discrimination of the irreducible $$t\bar{t}{+}b\bar{b}$$tt¯+bb¯ background. No significant excess of events above the background expectation is found and an observed (expected) limit of 3.4 (2.2) times the Standard Model cross section is obtained at 95 % confidence level. The ratio of the measured $${t\bar{t}H}$$tt¯H signal cross section to the Standard Model expectation is found to be $$\mu = 1.5 \pm 1.1$$μ=1.5±1.1 assuming a Higgs boson mass of 125$${{\,\mathrm GeV\,}}$$GeV.

    AB - A search for the Standard Model Higgs boson produced in association with a top-quark pair, $$t\bar{t}H$$tt¯H, is presented. The analysis uses 20.3 fb−1 of pp collision data at $$\sqrt{s}=8{{\,\mathrm TeV}}$$s=8TeV, collected with the ATLAS detector at the Large Hadron Collider during 2012. The search is designed for the $$H \rightarrow b\bar{b}$$H→bb¯ decay mode and uses events containing one or two electrons or muons. In order to improve the sensitivity of the search, events are categorised according to their jet and b-tagged jet multiplicities. A neural network is used to discriminate between signal and background events, the latter being dominated by $$t\bar{t}$$tt¯+jets production. In the single-lepton channel, variables calculated using a matrix element method are included as inputs to the neural network to improve discrimination of the irreducible $$t\bar{t}{+}b\bar{b}$$tt¯+bb¯ background. No significant excess of events above the background expectation is found and an observed (expected) limit of 3.4 (2.2) times the Standard Model cross section is obtained at 95 % confidence level. The ratio of the measured $${t\bar{t}H}$$tt¯H signal cross section to the Standard Model expectation is found to be $$\mu = 1.5 \pm 1.1$$μ=1.5±1.1 assuming a Higgs boson mass of 125$${{\,\mathrm GeV\,}}$$GeV.

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    U2 - 10.1140/epjc/s10052-015-3543-1

    DO - 10.1140/epjc/s10052-015-3543-1

    M3 - Article

    VL - 75

    JO - European Physical Journal C

    JF - European Physical Journal C

    SN - 1434-6044

    IS - 7

    M1 - 349

    ER -