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PublicationMeasurement of associated Z + charm production in proton–proton collisions at √s=8TeV(Springer New York LLC, 2018-04-01)A study of the associated production of a Z boson and a charm quark jet (Z + c), and a comparison to production with a b quark jet (Z + b), in p p collisions at a centre-of-mass energy of 8TeV are presented. The analysis uses a data sample corresponding to an integrated luminosity of 19.7fb-1, collected with the CMS detector at the CERN LHC. The Z boson candidates are identified through their decays into pairs of electrons or muons. Jets originating from heavy flavour quarks are identified using semileptonic decays of c or b flavoured hadrons and hadronic decays of charm hadrons. The measurements are performed in the kinematic region with two leptons with pTℓ>20GeV, | ηℓ| < 2.1 , 7125GeV and | ηjet| < 2.5. The Z + c production cross section is measured to be σ(pp→Z+c+X)B(Z→ℓ+ℓ-)=8.8±0.5(stat)±0.6(syst)pb. The ratio of the Z + c and Z + b production cross sections is measured to be σ(pp→Z+c+X)/σ(pp→Z+b+X)=2.0±0.2(stat)±0.2(syst). The Z + c production cross section and the cross section ratio are also measured as a function of the transverse momentum of the Z boson and of the heavy flavour jet. The measurements are compared with theoretical predictions.
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PublicationMeasurement of the Λb polarization and angular parameters in Λb →j /ψ Λ decays from pp collisions at s =7 and 8 TeV MEASUREMENT of the Λb POLARIZATION ⋯ A. M. SIRUNYAN et al.(American Physical Society, 2018-04-01)An analysis of the bottom baryon decay Λb→J/ψ(→μ+μ-)Λ(→pπ-) is performed to measure the Λb polarization and three angular parameters in data from pp collisions at s=7 and 8 TeV, collected by the CMS experiment at the Large Hadron Collider. The Λb polarization is measured to be 0.00±0.06(stat)±0.06(syst) and the parity-violating asymmetry parameter is determined to be 0.14±0.14(stat)±0.10(syst). The measurements are compared to various theoretical predictions, including those from perturbative quantum chromodynamics.
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PublicationChildren's health in developing countries: Issues of coping, child neglect and marginalization(Oxford University Press, 2009-09-01)This chapter presents a conceptual model to help understand the variables that play a role in the complex scenario of child neglect in poor communities in developing countries, their social marginalization, and their seclusion from the health care available to them. Communicable diseases are an important public health problem linked to poverty and other harsh socio-economic conditions. Traditional interventions against communicable diseases, such as educational programmes, are important, but they will have limited success in peri-urban areas because of the marginalization that exists, associated with unwanted and neglected children.
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PublicationMeasurements of the p p → Z Z production cross section and the Z → 4 ℓ branching fraction, and constraints on anomalous triple gauge couplings at √s=13TeV(Springer, 2018-02-01)Four-lepton production in proton-proton collisions, p p → (Z / γ∗) (Z / γ∗) → 4 ℓ, where ℓ= e or μ, is studied at a center-of-mass energy of 13TeV with the CMS detector at the LHC. The data sample corresponds to an integrated luminosity of 35.9fb-1. The ZZ production cross section, σ(pp→ZZ)=17.2±0.5(stat)±0.7(syst)±0.4(theo)±0.4(lumi) pb, measured using events with two opposite-sign, same-flavor lepton pairs produced in the mass region 60
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PublicationMeasurements of tt¯ cross sections in association with b jets and inclusive jets and their ratio using dilepton final states in pp collisions at s=13TeV(Elsevier B.V., 2018-01-10)The cross sections for the production of tt¯bb¯ and tt¯jj events and their ratio σtt¯bb¯/σtt¯jj are measured using data corresponding to an integrated luminosity of 2.3 fb−1collected in pp collisions at s=13 TeV with the CMS detector at the LHC. Events with two leptons (e or μ) and at least four reconstructed jets, including at least two identified as b quark jets, in the final state are selected. In the full phase space, the measured ratio is 0.022±0.003(stat)±0.006(syst), the cross section σtt¯bb¯ is 4.0±0.6(stat)±1.3(syst) pb and σtt¯jj is 184±6(stat)±33(syst) pb. The measurements are compared with the standard model expectations obtained from a POWHEG simulation at next-to-leading-order interfaced with PYTHIA.