1,447 research outputs found

    Multiplicity dependence of σψ(2S)/σJ/ψ\sigma_{\psi(2S)}/\sigma_{J/\psi} in pppp collisions at s=13\sqrt{s}=13 TeV

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    International audienceThe ratio of production cross-sections of ψ(2S)\psi(2S) over J/ψJ/\psi mesons as a function of charged-particle multiplicity in proton-proton collisions at a centre-of-mass energy s=13\sqrt{s}=13 TeV is measured with a data sample collected by the LHCb detector, corresponding to an integrated luminosity of 658 pb1^{-1}. The ratio is measured for both prompt and non-prompt ψ(2S)\psi(2S) and J/ψJ/\psi mesons. When there is an overlap between the rapidity ranges over which multiplicity and charmonia production are measured, a multiplicity-dependent modification of the ratio is observed for prompt mesons. No significant multiplicity dependence is found when the ranges do not overlap. For non-prompt production, the ψ(2S)toJ/ψ\psi(2S)-to-J/\psi production ratio is roughly independent of multiplicity irrespective of the rapidity range over which the multiplicity is measured. The results are compared to predictions of the co-mover model and agree well except in the low multiplicity region. The ratio of production cross-sections of ψ(2S)\psi(2S) over J/ψJ/\psi mesons are cross-checked with other measurements in di-lepton channels and found to be compatible

    Search for Bc+π+μ+μB_c^+\to\pi^+\mu^+\mu^- decays and measurement of the branching fraction ratio B(Bc+ψ(2S)π+)/B(Bc+J/ψπ+){\cal B}(B_c^+\to\psi(2S)\pi^+)/{\cal B}(B_c^+\to J/\psi \pi^+)

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    International audienceThe first search for nonresonant Bc+π+μ+μB_c^+\to\pi^+\mu^+\mu^- decays is reported. The analysis uses proton-proton collision data collected with the LHCb detector between 2011 and 2018, corresponding to an integrated luminosity of 9 fb1^{-1}. No evidence for an excess of signal events over background is observed and an upper limit is set on the branching fraction ratio B(Bc+π+μ+μ)/B(Bc+J/ψπ+)<2.1×104{\cal B}(B_c^+\to\pi^+\mu^+\mu^-)/{\cal B}(B_c^+\to J/\psi \pi^+) < 2.1\times 10^{-4} at 90%90\% confidence level. Additionally, an updated measurement of the ratio of the Bc+ψ(2S)π+B_c^+\to\psi(2S)\pi^+ and Bc+J/ψπ+B_c^+\to J/\psi \pi^+ branching fractions is reported. The ratio B(Bc+ψ(2S)π+)/B(Bc+J/ψπ+){\cal B}(B_c^+\to\psi(2S)\pi^+)/{\cal B}(B_c^+\to J/\psi \pi^+) is measured to be 0.254±0.018±0.003±0.0050.254\pm 0.018 \pm 0.003 \pm 0.005, where the first uncertainty is statistical, the second systematic, and the third is due to the uncertainties on the branching fractions of the leptonic J/ψJ/\psi and ψ(2S)\psi(2S) decays. This measurement is the most precise to date and is consistent with previous LHCb results

    Patients aged 90 years and above with Acute Coronary Syndrome in the Cardiac Intensive Care Unit: Management and Outcomes.

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    Limited data exist regarding outcomes after coronary angiography (CAG) and percutaneous coronary intervention (PCI) in patients aged ≥90 years admitted to the cardiac intensive care unit (CICU) with acute coronary syndrome (ACS). We studied sequential CICU patients ≥90 years admitted with ACS from 2007-2018. Three therapeutic approaches were defined: 1) No CAG; 2) CAG without PCI (CAG/No PCI); and 3) CAG with PCI (CAG/PCI). In-hospital mortality was evaluated using multivariable logistic regression. All-cause 1-year mortality was evaluated using Kaplan-Meier and multivariable Cox proportional-hazards analysis. The study included 239 patients with a median age of 92 (range 90-100) years (57% females; 45% STEMI; 8% cardiac arrest; 16% shock). The No CAG group had higher Day 1 Sequential Organ Failure Assessment score, more comorbidities, worse kidney function, and fewer STEMI. In-hospital mortality was 20.8% overall and did not differ between the No CAG (n = 103; 21.4%), CAG/No PCI (n = 47; 21.3%) and CAG/PCI (n = 90; 20.0%) groups, before or after adjustment. Overall 1-year mortality was 52.5% and did not differ between groups before or after adjustment. Median survival was 6.9 months overall and 41.2% of hospital survivors died within 1 year of CICU admission. CICU patients aged ≥90 with ACS have a substantial burden of illness with high in-hospital and 1-year mortality that was not lower in those who underwent CAG or PCI. These results suggest that careful patient selection for invasive coronary procedures is essential in this vulnerable population

    Momentum scale calibration of the LHCb spectrometer