148 research outputs found

    Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

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    The inclusive and dijet production cross-sections have been measured for jets containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass energy of sqrt(s) = 7 TeV, using the ATLAS detector at the LHC. The measurements use data corresponding to an integrated luminosity of 34 pb^-1. The b-jets are identified using either a lifetime-based method, where secondary decay vertices of b-hadrons in jets are reconstructed using information from the tracking detectors, or a muon-based method where the presence of a muon is used to identify semileptonic decays of b-hadrons inside jets. The inclusive b-jet cross-section is measured as a function of transverse momentum in the range 20 < pT < 400 GeV and rapidity in the range |y| < 2.1. The bbbar-dijet cross-section is measured as a function of the dijet invariant mass in the range 110 < m_jj < 760 GeV, the azimuthal angle difference between the two jets and the angular variable chi in two dijet mass regions. The results are compared with next-to-leading-order QCD predictions. Good agreement is observed between the measured cross-sections and the predictions obtained using POWHEG + Pythia. MC@NLO + Herwig shows good agreement with the measured bbbar-dijet cross-section. However, it does not reproduce the measured inclusive cross-section well, particularly for central b-jets with large transverse momenta.Comment: 10 pages plus author list (21 pages total), 8 figures, 1 table, final version published in European Physical Journal

    FCC-ee: The Lepton Collider: Future Circular Collider Conceptual Design Report Volume 2

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    In response to the 2013 Update of the European Strategy for Particle Physics, the Future Circular Collider (FCC) study was launched, as an international collaboration hosted by CERN. This study covers a highest-luminosity high-energy lepton collider (FCC-ee) and an energy-frontier hadron collider (FCC-hh), which could, successively, be installed in the same 100 km tunnel. The scientific capabilities of the integrated FCC programme would serve the worldwide community throughout the 21st century. The FCC study also investigates an LHC energy upgrade, using FCC-hh technology. This document constitutes the second volume of the FCC Conceptual Design Report, devoted to the electron-positron collider FCC-ee. After summarizing the physics discovery opportunities, it presents the accelerator design, performance reach, a staged operation scenario, the underlying technologies, civil engineering, technical infrastructure, and an implementation plan. FCC-ee can be built with today’s technology. Most of the FCC-ee infrastructure could be reused for FCC-hh. Combining concepts from past and present lepton colliders and adding a few novel elements, the FCC-ee design promises outstandingly high luminosity. This will make the FCC-ee a unique precision instrument to study the heaviest known particles (Z, W and H bosons and the top quark), offering great direct and indirect sensitivity to new physics

    FCC Physics Opportunities: Future Circular Collider Conceptual Design Report Volume 1

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    We review the physics opportunities of the Future Circular Collider, covering its e+e-, pp, ep and heavy ion programmes. We describe the measurement capabilities of each FCC component, addressing the study of electroweak, Higgs and strong interactions, the top quark and flavour, as well as phenomena beyond the Standard Model. We highlight the synergy and complementarity of the different colliders, which will contribute to a uniquely coherent and ambitious research programme, providing an unmatchable combination of precision and sensitivity to new physics

    Rare earth element and radionuclide distribution in surface sediments along an estuarine system affected by fertilizer industry contamination

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    Site-specific contamination related to fertilizer industry activity was demonstrated by light rare earth element (REE) anomalies (sum of La, Ce, Pr, Nd, Sm, and Eu concentrations up to 4.141 mg kg−1) and radionuclides (210Pb and 226Ra activities up to 994 and 498 Bq kg−1, respectively) from industrial contamination, within a subtropical estuary (SE Brazil). Anthropogenic influence was also supported by the site-specific 210Pb and 226Ra distribution down the estuarine system. The distribution of REE and radionuclide contamination varied along the estuary, which reflected differing sedimentation patterns of phosphogypsum and/or phosphate ore pollutants as identified downstream from the source, likely influenced by sediment–hydrodynamic processes within the estuarine system. Redox- and ion exchange-sensitive pollutants are mobile at the fresh–sea water interface causing an uneven distribution of the pollutants, indicating that the phosphgypsum and/or phosphate ore pollutant deposition can be also influenced by physical and/or geochemical processes associated to estuarine systems

    Gravidez na adolescĂȘncia e caracterĂ­sticas socioeconĂŽmicas dos municĂ­pios do Estado de SĂŁo Paulo, Brasil: anĂĄlise espacial Teenage pregnancy rates and socioeconomic characteristics of municipalities in SĂŁo Paulo State, Southeast Brazil: a spatial analysis

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    A gravidez na adolescĂȘncia Ă© um problema de saĂșde pĂșblica comum em todo o mundo. O objetivo deste estudo ecolĂłgico Ă© estudar o padrĂŁo espacial da associação entre os percentuais de gravidez na adolescĂȘncia e caracterĂ­sticas socioeconĂŽmicas dos municĂ­pios do Estado de SĂŁo Paulo, Brasil. Para isso, foi utilizado um modelo bayesiano com uma distribuição espacial que segue uma estrutura condicional autorregressiva (CAR), baseado em algoritmos Monte Carlo em cadeias de Markov (MCMC). Foram usados dados do Sistema de InformaçÔes sobre Nascidos Vivos (SINASC) e do Instituto Brasileiro de Geografia e EstatĂ­stica (IBGE). Verificou-se que a ocorrĂȘncia de gravidezes precoces apresentou-se maior nos municĂ­pios de menor produto interno bruto (PIB) per capita, com maior incidĂȘncia de pobreza, de menor tamanho populacional, menor Ă­ndice de desenvolvimento humano (IDH) e maior percentual de indivĂ­duos com Ă­ndice paulista de vulnerabilidade social (IPVS) igual a 5 ou 6, ou seja, mais vulnerĂĄveis. O estudo demonstra uma estreita associação entre gravidez na adolescĂȘncia e indicadores econĂŽmicos e sociais.<br>Teenage pregnancy is a common public health problem worldwide. The objective of this ecological study was to investigate the spatial association between teenage pregnancy rates and socioeconomic characteristics of municipalities in SĂŁo Paulo State, Southeast Brazil. We used a Bayesian model with a spatial distribution following a conditional autoregressive (CAR) form based on Markov Chain Monte Carlo algorithm. We used data from the Live Birth Information System (SINASC) and the Brazilian Institute of Geography and Statistics (IBGE). Early pregnancy was more frequent in municipalities with lower per capital gross domestic product (GDP), higher poverty rate, smaller population, lower human development index (HDI), and a higher percentage of individuals with State social vulnerability index of 5 or 6 (more vulnerable). The study demonstrates a significant association between teenage pregnancy and socioeconomic indicators
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