10 research outputs found

    Search for pair production of vector-like T and B quarks in single-lepton final states using boosted jet substructure in proton-proton collisions at root s=13 TeV

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    Abductive Partial Order Planning with Dependent Fluents

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    Search for R-parity violating supersymmetry in pp collisions at root s=13 TeV using bjets in a final state with a single lepton, many jets, and high sum of large-radius jet masses

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    Results are reported from a search for physics beyond the standard model in proton-proton collisions at a center-of-mass energy of root s=13TeV. The search uses a signature of a single lepton, large jet and bottom quark jet multiplicities, and high sum of large-radius jet masses, without any requirement on the missing transverse momentum in an event. The data sample corresponds to an integrated luminosity of 35.9 fb(-1) recorded by the CMS experiment at the LHC. No significant excess beyond the prediction from standard model processes is observed. The results are interpreted in terms of upper limits on the production cross section for R-parity violating supersymmetric extensions of the standard model using a benchmark model of gluino pair production, in which each gluino decays promptly via (g) over tilde -> tbs. Gluinos with a mass below 1610 GeV are excluded at 95% confidence level. (c) 2018 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP(3).Peer reviewe

    The global COVID-19 student survey:first wave results

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    University students have been particularly a!ected by the COVID-19 pandemic. We present results from the first wave of the Global COVID-19 Student Survey, which was administered at 28 universities in the United States, Spain, Australia, Sweden, Austria, Italy, and Mexico between April and October 2020. The survey addresses contemporaneous outcomes and future expectations regarding three fundamental aspects of students’ lives in the pandemic: the labor market, education, and health. We document the differential responses of students as a function of their country of residence, parental income, gender, and for the US their race

    Search for pair production of vector-like T and B quarks in single-lepton final states using boosted jet substructure in proton-proton collisions at root s=13 TeV

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    A search for pair production of massive vector-like T and B quarks in proton-proton collisions at root s = 13 TeV is presented. The data set was collected in 2015 by the CMS experiment at the LHC and corresponds to an integrated luminosity of up to 2.6 fb(-1). The T and B quarks are assumed to decay through three possible channels into a heavy boson (either a W, Z or Higgs boson) and a third generation quark. This search is performed in final states with one charged lepton and several jets, exploiting techniques to identify W or Higgs bosons decaying hadronically with large transverse momenta. No excess over the predicted standard model background is observed. Upper limits at 95% confidence level on the T quark pair production cross section are set that exclude T quark masses below 860 GeV in the singlet, and below 830 GeV in the doublet branching fraction scenario. For other branching fraction combinations with B (T -> tH) + B(T -> bW) >= 0.4, lower limits on the T quark range from 790 to 940 GeV. Limits are also set on pair production of singlet vector-like B quarks, which can be excluded up to a mass of 730 GeV. The techniques showcased here for understanding highly-boosted final states are important as the sensitivity to new particles is extended to higher masses

    Search for R-parity violating supersymmetry in pp collisions at root s=13 TeV using bjets in a final state with a single lepton, many jets, and high sum of large-radius jet masses

    No full text

    Search for R-parity violating supersymmetry in pp collisions at root s=13 TeV using bjets in a final state with a single lepton, many jets, and high sum of large-radius jet masses

    No full text
    Results are reported from a search for physics beyond the standard model in proton-proton collisions at a center-of-mass energy of root s=13TeV. The search uses a signature of a single lepton, large jet and bottom quark jet multiplicities, and high sum of large-radius jet masses, without any requirement on the missing transverse momentum in an event. The data sample corresponds to an integrated luminosity of 35.9 fb(-1) recorded by the CMS experiment at the LHC. No significant excess beyond the prediction from standard model processes is observed. The results are interpreted in terms of upper limits on the production cross section for R-parity violating supersymmetric extensions of the standard model using a benchmark model of gluino pair production, in which each gluino decays promptly via (g) over tilde -> tbs. Gluinos with a mass below 1610 GeV are excluded at 95% confidence level. (c) 2018 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP(3)

    Measurement of the ratio B(t -> Wb)/B(t -> Wq) in pp collisions at root s=8 TeV

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    The ratio of the top-quark branching fractions R=B(t→Wb)/B(t→Wq), where the denominator includes the sum over all down-type quarks (q = b, s, d), is measured in the tt- dilepton final state with proton-proton collision data at s=8 TeV from an integrated luminosity of 19.7 fb-1, collected with the CMS detector. In order to quantify the purity of the signal sample, the cross section is measured by fitting the observed jet multiplicity, thereby constraining the signal and background contributions. By counting the number of b jets per event, an unconstrained value of R=1.014±0.003(stat.)±0.032(syst.) is measured, in a good agreement with current precision measurements in electroweak and flavour sectors. A lower limit R>0.955 at the 95% confidence level is obtained after requiring R≤1, and a lower limit on the Cabibbo-Kobayashi-Maskawa matrix element |Vtb| > 0.975 is set at 95% confidence level. The result is combined with a previous CMS measurement of the t-channel single-top-quark cross section to determine the top-quark total decay width, Γt=1.36±0.02(stat.)-0.11+0.14(syst.) GeV. © 2014 Elsevier B.V
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