94 research outputs found

    Why Are Outcomes Different for Registry Patients Enrolled Prospectively and Retrospectively? Insights from the Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF).

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    Background: Retrospective and prospective observational studies are designed to reflect real-world evidence on clinical practice, but can yield conflicting results. The GARFIELD-AF Registry includes both methods of enrolment and allows analysis of differences in patient characteristics and outcomes that may result. Methods and Results: Patients with atrial fibrillation (AF) and ≥1 risk factor for stroke at diagnosis of AF were recruited either retrospectively (n = 5069) or prospectively (n = 5501) from 19 countries and then followed prospectively. The retrospectively enrolled cohort comprised patients with established AF (for a least 6, and up to 24 months before enrolment), who were identified retrospectively (and baseline and partial follow-up data were collected from the emedical records) and then followed prospectively between 0-18 months (such that the total time of follow-up was 24 months; data collection Dec-2009 and Oct-2010). In the prospectively enrolled cohort, patients with newly diagnosed AF (≤6 weeks after diagnosis) were recruited between Mar-2010 and Oct-2011 and were followed for 24 months after enrolment. Differences between the cohorts were observed in clinical characteristics, including type of AF, stroke prevention strategies, and event rates. More patients in the retrospectively identified cohort received vitamin K antagonists (62.1% vs. 53.2%) and fewer received non-vitamin K oral anticoagulants (1.8% vs . 4.2%). All-cause mortality rates per 100 person-years during the prospective follow-up (starting the first study visit up to 1 year) were significantly lower in the retrospective than prospectively identified cohort (3.04 [95% CI 2.51 to 3.67] vs . 4.05 [95% CI 3.53 to 4.63]; p = 0.016). Conclusions: Interpretations of data from registries that aim to evaluate the characteristics and outcomes of patients with AF must take account of differences in registry design and the impact of recall bias and survivorship bias that is incurred with retrospective enrolment. Clinical Trial Registration: - URL: http://www.clinicaltrials.gov . Unique identifier for GARFIELD-AF (NCT01090362)

    Measurements of the azimuthal anisotropy of prompt and nonprompt charmonia in PbPb collisions at <tex>\sqrt{s_{NN}}$</tex>=5.02 TeV

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    Abstract: The second-order (v(2)) and third-order (v(3)) Fourier coefficients describing the azimuthal anisotropy of prompt and nonprompt (from b-hadron decays) J/psi, as well as prompt psi(2S) mesons are measured in lead-lead collisions at a center-of-mass energy per nucleon pair of root s(NN) = 5.02TeV. The analysis uses a data set corresponding to an integrated luminosity of 1.61 nb(-1) recorded with the CMS detector. The J/psi and psi(2S) mesons are reconstructed using their dimuon decay channel. The v(2) and v(3) coefficients are extracted using the scalar product method and studied as functions of meson transverse momentum and collision centrality. The measured v(2) values for prompt J/psi mesons are found to be larger than those for nonprompt J/psi mesons. The prompt J/psi v(2) values at high pT are found to be underpredicted by a model incorporating only parton energy loss effects in a quark-gluon plasma medium. Prompt and nonprompt J/psi meson v(3) and prompt psi(2S) v(2) and v(3) values are also reported for the first time, providing new information about heavy quark interactions in the hot and dense medium created in heavy ion collisions

    Search for Z\u2032 bosons decaying to pairs of heavy Majorana neutrinos in proton-proton collisions at 1as=13 TeV

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    Abstract: A search for the production of pairs of heavy Majorana neutrinos (N-& ell;) from the decays of Z ' bosons is performed using the CMS detector at the LHC. The data were collected in proton-proton collisions at a center-of-mass energy of root s = 13 TeV, with an integrated luminosity of 138 fb(-1). The signature for the search is an excess in the invariant mass distribution of the final-state objects, two same-flavor leptons (e or mu) and at least two jets. No significant excess of events beyond the expected background is observed. Upper limits at 95% confidence level are set on the product of the Z ' production cross section and its branching fraction to a pair of N-& ell;, as functions of N-& ell; and Z ' boson masses (m(N & ell;) and m(Z '), respectively) for m(Z ') from 0.4 to 4.6 TeV and m(N & ell;) from 0.1 TeV to m(Z ')/2. In the theoretical framework of a left-right symmetric model, exclusion bounds in the m(N & ell;)-m(Z ') plane are presented in both the electron and muon channels. The observed upper limit on m(Z ') reaches up to 4.42 TeV. These are the most restrictive limits to date on the mass of N as a function of the Z ' boson mass

    Measurement of the B-s(0) \u2192 mu(+)mu(-) decay properties and search for the B-0 \u2192 mu(+)mu(-) decay in proton-proton collisions at 1as=13 TeV

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    Search for a high-mass dimuon resonance produced in association with b quark jets at 1as=13 TeV

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    Abstract: A search for high-mass dimuon resonance production in association with one or more b quark jets is presented. The study uses proton-proton collision data collected with the CMS detector at the LHC corresponding to an integrated luminosity of 138 fb(-1) at a center-of-mass energy of 13 TeV. Model-independent limits are derived on the number of signal events with exactly one or more than one b quark jet. Results are also interpreted in a lepton-flavor-universal model with Z boson couplings to a bb quark pair (g(b)), an sb quark pair (g(b)delta(bs)), and any same-flavor charged lepton (g(l)) or neutrino pair (g(nu)), with |g(nu)| = |g(l)|. For a Z ' boson with a mass mZ ' = 350 GeV (2 TeV) and |delta(bs)| sll measurements. In this scenario, most of the allowed parameter space is excluded for a Z ' boson with 350 < mZ ' < 500 GeV, while the constraints are less stringent for higher mZ ' hypotheses. This is the first dedicated search at the LHC for a high-mass dimuon resonance produced in association with multiple b quark jets, and the constraints obtained on models with this signature are the most stringent to date

    Evidence for four-top quark production in proton-proton collisions at s=13TeV

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    The production of four top quarks (tt¯tt¯) is studied with LHC proton-proton collision data samples collected by the CMS experiment at a center-of-mass energy of 13 TeV, and corresponding to integrated luminosities of up to 138 fb−1. Events that have no leptons (all-hadronic), one lepton, or two opposite-sign leptons (where lepton refers only to prompt electrons or prompt muons) are considered. This is the first tt¯tt¯ measurement that includes the all-hadronic final state. The observed significance of the tt¯tt¯ signal in these final states of 3.9 standard deviations (1.5 expected) provides evidence for tt¯tt¯ production, with a measured cross section of 36 +12−11 fb. Combined with earlier CMS results in other final states, the signal significance is 4.0 standard deviations (3.2 expected). The combination returns an observed cross section of 17 ± 4 (stat) ± 3 (syst) fb, which is consistent with the standard model prediction

    Measurements of inclusive and differential cross sections for the Higgs boson production and decay to four-leptons in proton-proton collisions at 1as=13 TeV

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    Abstract: Measurements of the inclusive and differential fiducial cross sections for the Higgs boson production in the H -> ZZ -> 4 l ( l = e, mu) decay channel are presented. The results are obtained from the analysis of proton-proton collision data recorded by the CMS experiment at the CERN LHC at a center-of-mass energy of 13TeV, corresponding to an integrated luminosity of 138 fb(-1). The measured inclusive fiducial cross section is 2.73 +/- 0.26 fb, in agreement with the standard model expectation of 2.86 +/- 0.1 fb. Differential cross sections are measured as a function of several kinematic observables sensitive to the Higgs boson production and decay to four leptons. A set of double-differential measurements is also performed, yielding a comprehensive characterization of the four leptons final state. Constraints on the Higgs boson trilinear coupling and on the bottom and charm quark coupling modifiers are derived from its transverse momentum distribution. All results are consistent with theoretical predictions from the standard model

    Measurement of the B0s & RARR; p. plus p.- decay properties and search for the B0 & RARR; p. plus p.- decay in proton-proton collisions at & RADIC;s=13 TeV

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    Evidence for four-top quark production in proton-proton collisions at s=13TeV

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    Search for new physics in multijet events with at least one photon and large missing transverse momentum in proton-proton collisions at 13 TeV

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    Abstract: A search for new physics in final states consisting of at least one photon, multiple jets, and large missing transverse momentum is presented, using proton-proton collision events at a center-of-mass energy of 13 TeV. The data correspond to an integrated luminosity of 137 fb(-1), recorded by the CMS experiment at the CERN LHC from 2016 to 2018. The events are divided into mutually exclusive bins characterized by the missing transverse momentum, the number of jets, the number of b-tagged jets, and jets consistent with the presence of hadronically decaying W, Z, or Higgs bosons. The observed data are found to be consistent with the prediction from standard model processes. The results are interpreted in the context of simplified models of pair production of supersymmetric particles via strong and electroweak interactions. Depending on the details of the signal models, gluinos and squarks of masses up to 2.35 and 1.43 TeV, respectively, and electroweakinos of masses up to 1.23 TeV are excluded at 95% confidence level
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