232 research outputs found

    Living in God's time: African-American faith and politics in post-emancipation North Carolina

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    This dissertation argues that black southerners' theology guided their collective action from emancipation to the beginning of the Jim Crow era. Black theology in this time produced both conservative and radical political agendas and set the terms for political debates within African-American communities. This project makes their rich, diverse, and at times confusing religious thought intelligible to the twenty-first-century reader and demonstrates the weight of those theological ideas on the ground in particular places and particular times. The branch of their theology that located them within a divine plan for the race--their eschatology--gave black political leaders more hope and confidence than a mere secular reading of their circumstances could justify. The dissertation focuses on one southern state, North Carolina, to reveal the importance of black theology to local and statewide political issues: emancipation and Reconstruction, migration and black land ownership, temperance and prohibition, and disfranchisement and segregation

    Search for long-lived heavy neutrinos in the decays of B mesons produced in proton-proton collisions at s\sqrt{s} = 13 TeV

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    International audienceA search for long-lived heavy neutrinos (N) in the decays of \PB mesons produced in proton-proton collisions at s\sqrt{s} = 13 TeV is presented. The data sample corresponds to an integrated luminosity of 41.6 fb1^{-1} collected in 2018 by the CMS experiment at the CERN LHC, using a dedicated data stream that enhances the number of recorded events containing B mesons. The search probes heavy neutrinos with masses in the range 1 <\ltmNm_\mathrm{N}<\lt 3 GeV and decay lengths in the range 102^{-2}<\ltcτc\tau<\lt 104^{4} mm, where τN\tau_\mathrm{N} is the N proper mean lifetime. Signal events are defined by the signature B \toB\ell_\mathrm{B}NX; N \to±π\ell^{\pm} \pi^{\mp}, where the leptons B\ell_\mathrm{B} and \ell can be either a muon or an electron, provided that at least one of them is a muon. The hadronic recoil system, X, is treated inclusively and is not reconstructed. No significant excess of events over the standard model background is observed in any of the ±π\ell^{\pm}\pi^{\mp} invariant mass distributions. Limits at 95% confidence level on the sum of the squares of the mixing amplitudes between heavy and light neutrinos, VN2\vert V_\mathrm{N}\vert^2, and on cτc\tau are obtained in different mixing scenarios for both Majorana and Dirac-like N particles. The most stringent upper limit VN2\vert V_\mathrm{N}\vert^2 <\lt 2.0×\times105^{-5} is obtained at mNm_\mathrm{N} = 1.95 GeV for the Majorana case where N mixes exclusively with muon neutrinos. The limits on VN2\vert V_\mathrm{N}\vert^2 for masses 1 <\lt mNm_\mathrm{N} <\lt 1.7 GeV are the most stringent from a collider experiment to date

    Search for baryon number violation in top quark production and decay using proton-proton collisions at s= \sqrt{s} = 13 TeV

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    A search is presented for baryon number violating interactions in top quark production and decay. The analysis uses data from proton-proton collisions at a center-of-mass energy of 13 TeV, collected with the CMS detector at the LHC with an integrated luminosity of 138 fb1 ^{-1} . Candidate events are selected by requiring two oppositely-charged leptons (electrons or muons) and exactly one jet identified as originating from a bottom quark. Multivariate discriminants are used to separate the signal from the background. No significant deviation from the standard model prediction is observed. Upper limits are placed on the strength of baryon number violating couplings. For the first time the production of single top quarks via baryon number violating interactions is studied. This allows the search to set the most stringent constraints to date on the branching fraction of the top quark decay to a lepton, an up-type quark (u or c), and a down-type quark (d, s, or b). The results improve the previous bounds by three to six orders of magnitude based on the fermion flavor combination of the baryon number violating interactions.A search is presented for baryon number violating interactions in top quark production and decay. The analysis uses data from proton-proton collisions at a center-of-mass energy of 13 TeV, collected with the CMS detector at the LHC with an integrated luminosity of 138 fb1^{-1}. Candidate events are selected by requiring two oppositely-charged leptons (electrons or muons) and exactly one jet identified as originating from a bottom quark. Multivariate discriminants are used to separate the signal from the background. No significant deviation from the standard model prediction is observed. Upper limits are placed on the strength of baryon number violating couplings. For the first time the production of single top quarks via baryon number violating interactions is studied. This allows the search to set the most stringent constraints to date on the branching fraction of the top quark decay to a lepton, an up-type quark (u or c), and a down-type quark (d, s, or b). The results improve the previous bounds by three to six orders of magnitude based on the fermion flavor combination of the baryon number violating interactions

    Observation of the Ξb\Xi^-_\mathrm{b}\toψ\psi(2S)Ξ\Xi^- decay and studies of the Ξb0\Xi_\mathrm{b}^{\ast{}0} baryon in proton-proton collisions at s\sqrt{s} = 13 TeV

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    International audienceThe first observation of the decay Ξb\Xi^-_\mathrm{b}\toψ\psi(2S)Ξ\Xi^- and measurement of the branching ratio of Ξb\Xi^-_\mathrm{b}\toψ\psi(2S)Ξ\Xi^- to Ξb\Xi^-_\mathrm{b}\to J/ψ\psiΞ\Xi^- are presented. The J/ψ\psi and ψ\psi(2S) mesons are reconstructed using their dimuon decay modes. The results are based on proton-proton colliding beam data from the LHC collected by the CMS experiment at s\sqrt{s} = 13 TeV in 2016-2018, corresponding to an integrated luminosity of 140 fb1^{-1}. The branching fraction ratio is measured to be B\mathcal{B}(Ξb\Xi^-_\mathrm{b}\toψ\psi(2S)Ξ\Xi^-)/B\mathcal{B}(Ξb\Xi^-_\mathrm{b}\to J/ψ\psiΞ\Xi^-) = 0.840.19+0.21^{+0.21}_{-0.19} (stat) ±\pm 0.10 (syst) ±\pm 0.02 (B\mathcal{B}), where the last uncertainty comes from the uncertainties in the branching fractions of the charmonium states. New measurements of the Ξb0\Xi_\mathrm{b}^{\ast{}0} baryon mass and natural width are also presented, using the Ξbπ+\Xi_\mathrm{b}^-\pi^+ final state, where the Ξb\Xi^-_\mathrm{b} baryon is reconstructed through the decays J/ψΞ\psi \Xi^-, ψ\psi(2S)Ξ\Xi^-, J/ψΛ\psi \LambdaK^-, and J/ψΣ0\psi \Sigma^0K^-. Finally, the fraction of the Ξb\Xi^-_\mathrm{b} baryons produced from Ξb0\Xi_\mathrm{b}^{\ast{}0} decays is determined

    Search for the decay of the Higgs boson to a pair of light pseudoscalar bosons in the final state with four bottom quarks in proton-proton collisions at s\sqrt{s} = 13 TeV

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    International audienceA search is presented for the decay of the 125 GeV Higgs boson (H) to a pair of new light pseudoscalar bosons (a), followed by the prompt decay of each a boson to a bottom quark-antiquark pair, H \to aa \tobbˉbbˉ\mathrm{b\bar{b}b\bar{b}}. The analysis is performed using a data sample of proton-proton collisions collected with the CMS detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb1^{-1}. To reduce the background from standard model processes, the search requires the Higgs boson to be produced in association with a leptonically decaying W or Z boson. The analysis probes the production of new light bosons in a 15 <\ltmam_\mathrm{a}<\lt 60 GeV mass range. Assuming the standard model predictions for the Higgs boson production cross sections for pp \to WH and ZH, model independent upper limits at 95% confidence level are derived for the branching fraction B\mathcal{B}(H \to aa \to bbˉbbˉ\mathrm{b\bar{b}b\bar{b}}). The combined WH and ZH observed upper limit on the branching fraction ranges from 1.10 for ma=m_\mathrm{a} = 20 GeV to 0.36 for ma=m_\mathrm{a} = 60 GeV, complementing other measurements in the μμττ\mu\mu\tau\tau, ττττ\tau\tau\tau\tau and bb\ell\ell (=\ell= μ\mu,τ\tau) channels

    Observation of the Ξb\Xi^-_\mathrm{b}\toψ\psi(2S)Ξ\Xi^- decay and studies of the Ξb0\Xi_\mathrm{b}^{\ast{}0} baryon in proton-proton collisions at s\sqrt{s} = 13 TeV

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    The first observation of the decay Ξb\Xi^-_\mathrm{b}\toψ\psi(2S)Ξ\Xi^- and measurement of the branching ratio of Ξb\Xi^-_\mathrm{b}\toψ\psi(2S)Ξ\Xi^- to Ξb\Xi^-_\mathrm{b}\to J/ψ\psiΞ\Xi^- are presented. The J/ψ\psi and ψ\psi(2S) mesons are reconstructed using their dimuon decay modes. The results are based on proton-proton colliding beam data from the LHC collected by the CMS experiment at s\sqrt{s} = 13 TeV in 2016-2018, corresponding to an integrated luminosity of 140 fb1^{-1}. The branching fraction ratio is measured to be B\mathcal{B}(Ξb\Xi^-_\mathrm{b}\toψ\psi(2S)Ξ\Xi^-)/B\mathcal{B}(Ξb\Xi^-_\mathrm{b}\to J/ψ\psiΞ\Xi^-) = 0.840.19+0.21^{+0.21}_{-0.19} (stat) ±\pm 0.10 (syst) ±\pm 0.02 (B\mathcal{B}), where the last uncertainty comes from the uncertainties in the branching fractions of the charmonium states. New measurements of the Ξb0\Xi_\mathrm{b}^{\ast{}0} baryon mass and natural width are also presented, using the Ξbπ+\Xi_\mathrm{b}^-\pi^+ final state, where the Ξb\Xi^-_\mathrm{b} baryon is reconstructed through the decays J/ψΞ\psi \Xi^-, ψ\psi(2S)Ξ\Xi^-, J/ψΛ\psi \LambdaK^-, and J/ψΣ0\psi \Sigma^0K^-. Finally, the fraction of the Ξb\Xi^-_\mathrm{b} baryons produced from Ξb0\Xi_\mathrm{b}^{\ast{}0} decays is determined

    Review of top quark mass measurements in CMS

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    International audienceThe top quark mass is one of the most intriguing parameters of the standard model (SM). Its value indicates a Yukawa coupling close to unity, and the resulting strong ties to the Higgs physics make the top quark mass a crucial ingredient for understanding essential aspects of the electroweak sector of the SM. While it is such an important parameter of the SM, its measurement and interpretation in terms of the Lagrangian parameter are challenging. The CMS Collaboration has performed multiple measurements of the top quark mass, addressing these challenges from different angles: highly precise `direct' measurements, using the top quark decay products, as well as `indirect' measurements aiming at accurate interpretations in terms of the Lagrangian parameter. Recent mass measurements using Lorentz-boosted top quarks are particularly promising, opening a new avenue of measurements based on top quark decay products contained in a single particle jet, with superior prospects for accurate theoretical interpretations. Moreover, dedicated studies of the dominant uncertainties in the modelling of the signal processes have been performed. This review offers the first comprehensive overview of these measurements performed by the CMS Collaboration using the data collected at centre-of-mass energies of 7, 8, and 13 TeV

    Observation of the Ξb\Xi^-_\mathrm{b}\toψ\psi(2S)Ξ\Xi^- decay and studies of the Ξb0\Xi_\mathrm{b}^{\ast{}0} baryon in proton-proton collisions at s\sqrt{s} = 13 TeV

    No full text
    International audienceThe first observation of the decay Ξb\Xi^-_\mathrm{b}\toψ\psi(2S)Ξ\Xi^- and measurement of the branching ratio of Ξb\Xi^-_\mathrm{b}\toψ\psi(2S)Ξ\Xi^- to Ξb\Xi^-_\mathrm{b}\to J/ψ\psiΞ\Xi^- are presented. The J/ψ\psi and ψ\psi(2S) mesons are reconstructed using their dimuon decay modes. The results are based on proton-proton colliding beam data from the LHC collected by the CMS experiment at s\sqrt{s} = 13 TeV in 2016-2018, corresponding to an integrated luminosity of 140 fb1^{-1}. The branching fraction ratio is measured to be B\mathcal{B}(Ξb\Xi^-_\mathrm{b}\toψ\psi(2S)Ξ\Xi^-)/B\mathcal{B}(Ξb\Xi^-_\mathrm{b}\to J/ψ\psiΞ\Xi^-) = 0.840.19+0.21^{+0.21}_{-0.19} (stat) ±\pm 0.10 (syst) ±\pm 0.02 (B\mathcal{B}), where the last uncertainty comes from the uncertainties in the branching fractions of the charmonium states. New measurements of the Ξb0\Xi_\mathrm{b}^{\ast{}0} baryon mass and natural width are also presented, using the Ξbπ+\Xi_\mathrm{b}^-\pi^+ final state, where the Ξb\Xi^-_\mathrm{b} baryon is reconstructed through the decays J/ψΞ\psi \Xi^-, ψ\psi(2S)Ξ\Xi^-, J/ψΛ\psi \LambdaK^-, and J/ψΣ0\psi \Sigma^0K^-. Finally, the fraction of the Ξb\Xi^-_\mathrm{b} baryons produced from Ξb0\Xi_\mathrm{b}^{\ast{}0} decays is determined

    Review of top quark mass measurements in CMS

    No full text
    International audienceThe top quark mass is one of the most intriguing parameters of the standard model (SM). Its value indicates a Yukawa coupling close to unity, and the resulting strong ties to the Higgs physics make the top quark mass a crucial ingredient for understanding essential aspects of the electroweak sector of the SM. While it is such an important parameter of the SM, its measurement and interpretation in terms of the Lagrangian parameter are challenging. The CMS Collaboration has performed multiple measurements of the top quark mass, addressing these challenges from different angles: highly precise `direct' measurements, using the top quark decay products, as well as `indirect' measurements aiming at accurate interpretations in terms of the Lagrangian parameter. Recent mass measurements using Lorentz-boosted top quarks are particularly promising, opening a new avenue of measurements based on top quark decay products contained in a single particle jet, with superior prospects for accurate theoretical interpretations. Moreover, dedicated studies of the dominant uncertainties in the modelling of the signal processes have been performed. This review offers the first comprehensive overview of these measurements performed by the CMS Collaboration using the data collected at centre-of-mass energies of 7, 8, and 13 TeV

    Search for long-lived particles using displaced vertices and missing transverse momentum in proton-proton collisions at s\sqrt{s} = 13 TeV

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    A search for the production of long-lived particles in proton-proton collisions at a center-of-mass energy of 13 TeV at the CERN LHC is presented. The search is based on data collected by the CMS experiment in 2016-2018, corresponding to a total integrated luminosity of 137 fb1^{-1}. This search is designed to be sensitive to long-lived particles with mean proper decay lengths between 0.1 and 1000 μ\mum, whose decay products produce a final state with at least one displaced vertex and missing transverse momentum. A machine learning algorithm, which improves the background rejection power by more than an order of magnitude, is applied to improve the sensitivity. The observation is consistent with the standard model background prediction, and the results are used to constrain split supersymmetry (SUSY) and gauge-mediated SUSY breaking models with different gluino mean proper decay lengths and masses. This search is the first CMS search that shows sensitivity to hadronically decaying long-lived particles from signals with mass differences between the gluino and neutralino below 100 GeV. It sets the most stringent limits to date for split-SUSY models and gauge-mediated SUSY breaking models with gluino proper decay length less than 6 μ\mum
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