72 research outputs found

    Congenital malaria in Urabá, Colombia

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    <p>Abstract</p> <p>Background</p> <p>Congenital malaria has been considered a rare event; however, recent reports have shown frequencies ranging from 3% to 54.2% among newborns of mothers who had suffered malaria during pregnancy. There are only a few references concerning the epidemiological impact of this entity in Latin-America and Colombia.</p> <p>Objective</p> <p>The aim of the study was to measure the prevalence of congenital malaria in an endemic Colombian region and to determine some of its characteristics.</p> <p>Methods</p> <p>A prospective, descriptive study was carried out in the mothers who suffered malaria during pregnancy and their newborns. Neonates were clinically evaluated at birth and screened for <it>Plasmodium spp</it>. infection by thick smear from the umbilical cord and peripheral blood, and followed-up weekly during the first 21 days of postnatal life through clinical examinations and thick smears.</p> <p>Results</p> <p>116 newborns were included in the study and 80 umbilical cord samples were obtained. Five cases of congenital infection were identified (four caused by <it>P. vivax </it>and one by <it>P. falciparum</it>), two in umbilical cord blood and three in newborn peripheral blood. One case was diagnosed at birth and the others during follow-up. Prevalence of congenital infection was 4.3%. One of the infected newborns was severely ill, while the others were asymptomatic and apparently healthy. The mothers of the newborns with congenital malaria had been diagnosed with malaria in the last trimester of pregnancy or during delivery, and also presented placental infection.</p> <p>Conclusions</p> <p>Congenital malaria may be a frequent event in newborns of mothers who have suffered malaria during pregnancy in Colombia. An association was found between congenital malaria and the diagnosis of malaria in the mother during the last trimester of pregnancy or during delivery, and the presence of placental infection.</p

    Observation of B(s)0→J/ψpp¯ decays and precision measurements of the B(s)0 masses

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    The first observation of the decays B 0 ( s ) → J / ψ p ¯ p is reported, using proton-proton collision data corresponding to an integrated luminosity of 5.2     fb − 1 , collected with the LHCb detector. These decays are suppressed due to limited available phase space, as well as due to Okubo-Zweig-Iizuka or Cabibbo suppression. The measured branching fractions are B ( B 0 → J / ψ p ¯ p ) = [ 4.51 ± 0.40 ( stat ) ± 0.44 ( syst ) ] × 10 − 7 , B ( B 0 s → J / ψ p ¯ p ) = [ 3.58 ± 0.19 ( stat ) ± 0.39 ( syst ) ] × 10 − 6 . For the B 0 s meson, the result is much higher than the expected value of O ( 10 − 9 ) . The small available phase space in these decays also allows for the most precise single measurement of both the B 0 mass as 5279.74 ± 0.30 ( stat ) ± 0.10 ( syst )     MeV and the B 0 s mass as 5366.85 ± 0.19 ( stat ) ± 0.13 ( syst )     MeV

    Observation of the decay Λ <sub>b</sub> <sup>0</sup>  → ψ(2S)pπ<sup>−</sup>

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    International audienceThe Cabibbo-suppressed decay Λb0_{b}^{0}  → ψ(2S)pπ^{−} is observed for the first time using a data sample collected by the LHCb experiment in proton-proton collisions corresponding to 1.0, 2.0 and 1.9 fb1^{−1} of integrated luminosity at centre-of-mass energies of 7, 8 and 13 TeV, respectively. The ψ(2S) mesons are reconstructed in the μ+^{+}μ^{−} final state. The branching fraction with respect to that of the Λb0_{b}^{0}  → ψ(2S)pK^{−} decay mode is measured to b

    Measurement of the B_{s}^{0}→μ^{+}μ^{-} Branching Fraction and Effective Lifetime and Search for B^{0}→μ^{+}μ^{-} Decays.

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    A search for the rare decays B_{s}^{0}→μ^{+}μ^{-} and B^{0}→μ^{+}μ^{-} is performed at the LHCb experiment using data collected in pp collisions corresponding to a total integrated luminosity of 4.4  fb^{-1}. An excess of B_{s}^{0}→μ^{+}μ^{-} decays is observed with a significance of 7.8 standard deviations, representing the first observation of this decay in a single experiment. The branching fraction is measured to be B(B_{s}^{0}→μ^{+}μ^{-})=(3.0±0.6_{-0.2}^{+0.3})×10^{-9}, where the first uncertainty is statistical and the second systematic. The first measurement of the B_{s}^{0}→μ^{+}μ^{-} effective lifetime, τ(B_{s}^{0}→μ^{+}μ^{-})=2.04±0.44±0.05  ps, is reported. No significant excess of B^{0}→μ^{+}μ^{-} decays is found, and a 95% confidence level upper limit, B(B^{0}→μ^{+}μ^{-})<3.4×10^{-10}, is determined. All results are in agreement with the standard model expectations

    Search for CP violation in Λb0→pK− and Λb0→pπ− decays

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    A search for CP violation in Λb0→pK− and Λb0→pπ− decays is presented using a sample of pp collisions collected with the LHCb detector and corresponding to an integrated luminosity of 3.0fb−1. The CP -violating asymmetries are measured to be ACPpK−=−0.020±0.013±0.019 and ACPpπ−=−0.035±0.017±0.020, and their difference ACPpK−−ACPpπ−=0.014±0.022±0.010, where the first uncertainties are statistical and the second systematic. These are the most precise measurements of such asymmetries to date

    Evidence for an nc(1S)ff- resonance in B0 yc(1S)K+ decays

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    A Dalitz plot analysis of B0→ηc(1S)K+π- decays is performed using data samples of pp collisions collected with the LHCb detector at centre-of-mass energies of s=7,8 and 13TeV , corresponding to a total integrated luminosity of 4.7fb-1 . A satisfactory description of the data is obtained when including a contribution representing an exotic ηc(1S)π- resonant state. The significance of this exotic resonance is more than three standard deviations, while its mass and width are 4096±20-22+18MeV and 152±58-35+60MeV , respectively. The spin-parity assignments JP=0+ and JP=1- are both consistent with the data. In addition, the first measurement of the B0→ηc(1S)K+π- branching fraction is performed and gives B(B0→ηc(1S)K+π-)=(5.73±0.24±0.13±0.66)×10-4, where the first uncertainty is statistical, the second systematic, and the third is due to limited knowledge of external branching fractions

    Measurement of the B0s→μ+μ− Branching Fraction and Effective Lifetime and Search for B0→μ+μ− Decays

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    See paper for full list of authors - All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2017-001.html - Submitted to Phys. Rev. Lett.International audienceA search for the rare decays B0s→μ+μ− and B0→μ+μ− is performed at the LHCb experiment using data collected in pp collisions corresponding to a total integrated luminosity of 4.4 fb−1. An excess of B0s→μ+μ− decays is observed with a significance of 7.8 standard deviations, representing the first observation of this decay in a single experiment. The branching fraction is measured to be B(B0s→μ+μ−)=(3.0±0.6+0.3−0.2)×10−9, where the first uncertainty is statistical and the second systematic. The first measurement of the B0s→μ+μ− effective lifetime, τ(B0s→μ+μ−)=2.04±0.44±0.05 ps, is reported. No significant excess of B0→μ+μ− decays is found and a 95 % confidence level upper limit, B(B0→μ+μ−)<3.4×10−10, is determined. All results are in agreement with the Standard Model expectations

    Observation of Five New Narrow Omega(0)(c) States Decaying to Xi K-+(c)-

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    The Ξc+K\Xi_c^+ K^- mass spectrum is studied with a sample of pppp collision data corresponding to an integrated luminosity of 3.3 fb1^{-1}, collected by the LHCb experiment. The Ξc+\Xi_c^+ is reconstructed in the decay mode pKπ+p K^- \pi^+. Five new, narrow excited Ωc0\Omega_c^0 states are observed: the Ωc(3000)0\Omega_c(3000)^0, Ωc(3050)0\Omega_c(3050)^0, Ωc(3066)0\Omega_c(3066)^0, Ωc(3090)0\Omega_c(3090)^0, and Ωc(3119)0\Omega_c(3119)^0. Measurements of their masses and widths are reported.Comment: 14 pages, 3 figures. All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2017-002.htm

    Amplitude analysis of the B0 (s)! K0K0 decays and measurement of the branching fraction of the B0! K0K0 decay

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    The B0K0K0B^0 \to K^{*0} \overline{K}^{*0} and Bs0K0K0B^0_s \to K^{*0} \overline{K}^{*0} decays are studied using proton-proton collision data corresponding to an integrated luminosity of 3fb1^{-1}. An untagged and time-integrated amplitude analysis of B(s)0(K+π)(Kπ+)B^0_{(s)} \to (K^+\pi^-)(K^-\pi^+) decays in two-body invariant mass regions of 150 MeV/c2/c^2 around the K0K^{*0} mass is performed. A stronger longitudinal polarisation fraction in the B0K0K0{B^0 \to K^{*0} \overline{K}^{*0}} decay, fL=0.724±0.051(stat)±0.016(syst){f_L = 0.724 \pm 0.051 \,({\rm stat}) \pm 0.016 \,({\rm syst})}, is observed as compared to fL=0.240±0.031(stat)±0.025(syst){f_L = 0.240 \pm 0.031 \,({\rm stat}) \pm 0.025 \,({\rm syst})} in the Bs0K0K0{B^0_s\to K^{*0} \overline{K}^{*0}} decay. The ratio of branching fractions of the two decays is measured and used to determine B(B0K0K0)=(8.0±0.9(stat)±0.4(syst))×107\mathcal{B}(B^0 \to K^{*0} \overline{K}^{*0}) = (8.0 \pm 0.9 \,({\rm stat}) \pm 0.4 \,({\rm syst})) \times 10^{-7}.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2019-004.html (LHCb public pages

    Search for Lepton-Universality Violation in B^{+}→K^{+}ℓ^{+}ℓ^{-} Decays.

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    A measurement of the ratio of branching fractions of the decays B^{+}→K^{+}μ^{+}μ^{-} and B^{+}→K^{+}e^{+}e^{-} is presented. The proton-proton collision data used correspond to an integrated luminosity of 5.0  fb^{-1} recorded with the LHCb experiment at center-of-mass energies of 7, 8, and 13 TeV. For the dilepton mass-squared range 1.1<q^{2}<6.0  GeV^{2}/c^{4} the ratio of branching fractions is measured to be R_{K}=0.846_{-0.054}^{+0.060}_{-0.014}^{+0.016}, where the first uncertainty is statistical and the second systematic. This is the most precise measurement of R_{K} to date and is compatible with the standard model at the level of 2.5 standard deviations
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