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

Predictors of academic achievement and academic self-concept: a longitudinal perspective

Background. A large body of research supports the existence of an academic achievement - self-concept relationship. Path analyses mostly show academic achievement to be causally predominant in this relationship. Aims. This study aims to replicate these findings among Belgian primary school-age children, controlling for a number of other relevant variables such as school commitment, parental socio-economic status (SES), gender and teacher expectations. The longitudinal design of this study makes it particularly suited for this purpose. Method. Data were analysed using correlation, regressions of time 1 independent variables on time 2 dependent variables, multiple classification analysis and path analysis using LISREL. Results. Academic self-concept and academic achievement were found to be strong predictors of one another, even controlling for other variables and stability of both over time. The only other variable to enter significantly into regressions on time 2 academic achievement and academic self-concept was parental socio-economic status (SES). Both the regression analyses and path analysis undertaken specifically to test causal predominance found achievement to be causally predominant in this sample. Conclusion. The fact that academic achievement was causally predominant over academic self-concept, that global self-esteem was not a significant predictor of achievement, and the significant contribution of parental SES to achievement all suggest that self-esteem enhancement in itself cannot be a solution to the problem of academic failure

7.5 Researching Equity and Effectiveness in Education: Examples from the UK and Germany

Many examples of educational research, including international comparative school achievement studies have clearly documented that school attainments and school careers of children are linked in many countries to their origins (ethnic and cultural) and the socioeconomic situation of the family they grow up in. However, the extent of the equity gap for specific student groups and explanations for it vary. As consequence, a number of longitudinal educational studies have been set up to investigate these phenomena and shed light on the question how to overcome such inequity. The current chapter first explores different definitions of equity and presents then two large, longitudinal studies conducted in England and Germany that investigate children’s development from preschool age through primary education. Both studies were set up to investigate the influences of individual child, family, home learning, preschool and primary school influences on children’s development. A core question of both studies is how (pre-)school can contribute to reducing the negative influence of early childhood disadvantage and thus potentially help reduce inequity in later educational outcomes (see Sammons, Anders and Hall, 2013 for further discussion). The Effective Provision of Pre-, Primary and Secondary Project in England (EPPSE) has tracked 3000+ children since 1996, whereas the German BiKS-study is investigating the development of around 550 children. The two studies share many similarities in their designs and methodological approaches, although there are also some important differences. Recent results of both studies are presented and discussed in terms of both the quantitative modeling strategies adopted and the interpretation of statistical findings

Search for the standard model Higgs boson at LEP

The four LEP Collaborations, ALEPH, DELPHI, L3 and OPAL, have collected a total of 2461 pb(-1) of e(+)e(-) collision data at centre-of-mass energies between 189 and 209 GeV. The data are used to search for the Standard Model Higgs boson. The search results of the four Collaborations are combined and examined in a likelihood test for their consistency with two hypotheses: the background hypothesis and the signal plus background hypothesis. The corresponding confidences have been computed as functions of the hypothetical Higgs boson mass. A lower bound of 114.4 GeV/c(2) is established, at the 95% confidence level, on the mass of the Standard Model Higgs boson. The LEP data are also used to set upper bounds on the HZZ coupling for various assumptions concerning the decay of the Higgs boson. (C) 2003 Elsevier B.V. All rights reserved