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

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

Measurement of charged-particle event shape variables in inclusive root(s)=7 TeV proton-proton interactions with the ATLAS detector

The measurement of charged-particle event shape variables is presented in inclusive inelastic pp collisions at a center-of-mass energy of 7 TeV using the ATLAS detector at the LHC. The observables studied are the transverse thrust, thrust minor, and transverse sphericity, each defined using the final-state charged particles' momentum components perpendicular to the beam direction. Events with at least six charged particles are selected by a minimum-bias trigger. In addition to the differential distributions, the evolution of each event shape variable as a function of the leading charged-particle transverse momentum, charged-particle multiplicity, and summed transverse momentum is presented. Predictions from several Monte Carlo models show significant deviations from data

Measurement of the production cross section for W-bosons in association with jets in pp collisions at √s=7 TeV with the ATLAS detector

This Letter reports on a first measurement of the inclusive W + jets cross section in proton–proton collisions at a centre-of-mass energy of 7 TeV at the LHC, with the ATLAS detector. Cross sections, in both the electron and muon decay modes of the W -boson, are presented as a function of jet multiplicity and of the transverse momentum of the leading and next-to-leading jets in the event. Measurements are also presented of the ratio of cross sections σ(W + n)/σ(W + n − 1) for inclusive jet multiplicities n = 1–4. The results, based on an integrated luminosity of 1.3 pb−1, have been corrected for all known detector effects and are quoted in a limited and well-defined range of jet and lepton kinematics. The measured cross sections are compared to particle-level predictions based on perturbative QCD. Next-toleading order calculations, studied here for n 2, are found in good agreement with the data. Leadingorder multiparton event generators, normalized to the NNLO total cross section, describe the data well for all measured jet multiplicities.

A mortalidade materna nas capitais brasileiras: algumas características e estimativa de um fator de ajuste Maternal mortality in Brazilian State Capitals: some characteristics and estimates for an adjustment factor

A mortalidade materna pode ser considerada um excelente indicador de saúde, não só da mulher, mas da população geral; mostra, também, iniqüidades. A redução da mortalidade materna é uma das principais metas, estando também incluída nas Metas do Desenvolvimento do Milênio da ONU. OBJETIVO: Conhecer a qualidade da informação da mortalidade de mulheres de 10 a 49 anos, e estimar a razão de mortalidade materna (RMM) e os fatores de ajuste para os dados oficiais, no conjunto das capitais de estados brasileiros e Distrito Federal. METODOLOGIA: Adotou-se a metodologia RAMOS (a partir da declaração de óbito, entrevista no domicílio da mulher falecida, com preenchimento de questionário, sobre variáveis demográficas, epidemiológicas, clínicas e de acesso a serviços; seguiam-se consultas a prontuários médicos hospitalares e a laudos de autópsia). Após o resgate da informação, pôde ser feita análise das reais causas básicas, terminais e associadas. A população de estudo foi estimada em 7.332 mortes de mulheres de 10 a 49 anos, ocorridas no primeiro semestre de 2002, sendo 239 óbitos por causas maternas. A RMM foi de 54,3 por cem mil nascidos vivos (n.v.), no conjunto de capitais, variando entre 42 por cem mil n.v. no Sul, e 73,2 por cem mil n.v. no Nordeste. O fator de ajuste para o conjunto das capitais brasileiras foi igual a 1,4; para as regiões (considerando apenas as capitais), variaram entre 1,08 na Região Norte e 1,83 na Região Sul. As mortes obstétricas diretas corresponderam a 67,1%, mostrando que assistência ao pré-natal, ao parto e ao puerpério deve ser aprimorada.<br>INTRODUCTION: There is criticism as to the heterogeneity and reliability of mortality data in Brazilian Regions. However, official mortality statistics of State Capitals are more accurate and have adequate coverage. Reduction of maternal mortality is one of the world's major goals and it is measured by the Maternal Mortality Ratio. International agencies have been estimating that the Brazilian ratio is very high. An investigation was carried out to know the actual value. OBJECTIVE: The aim was to calculate the maternal mortality ratio for Brazilian Capitals and the Federal District and estimate an adjustment factor for official data. METHODOLOGY: A total of 7,332 deaths that occurred in the first semester of 2002 in women from 10 to 49 years of age living in these areas were investigated, using the RAMOS methodology (household interviews and investigation of medical and hospital records and autopsies.). RESULTS: The maternal mortality ratio calculated was 54.3 per 100,000 live born, ranging between 73.2 in the North State Capitals and 42 per 100,000 live born in the South. The lowest adjustment factors were 1.08 in the North Region, and 1.10 in the Middle West State Capitals. The highest values were 1.76 and 1.83 in the Northeast and South Regions. Considering the set of Brazilian State Capitals, the adjustment factor estimated was equal to 1.4. The maternal mortality ratios observed were lower than WHO, UNICEF and UNFPA values. Direct obstetric maternal deaths accounted for 67.1% of the total, thus indicating that pre-natal and childbirth care must be improved