Time-integrated luminosity recorded by the BABAR detector at the PEP-II e+e- collider

This article is the Preprint version of the final published artcile which can be accessed at the link below.We describe a measurement of the time-integrated luminosity of the data collected by the BABAR experiment at the PEP-II asymmetric-energy e+e- collider at the ϒ(4S), ϒ(3S), and ϒ(2S) resonances and in a continuum region below each resonance. We measure the time-integrated luminosity by counting e+e-→e+e- and (for the ϒ(4S) only) e+e-→μ+μ- candidate events, allowing additional photons in the final state. We use data-corrected simulation to determine the cross-sections and reconstruction efficiencies for these processes, as well as the major backgrounds. Due to the large cross-sections of e+e-→e+e- and e+e-→μ+μ-, the statistical uncertainties of the measurement are substantially smaller than the systematic uncertainties. The dominant systematic uncertainties are due to observed differences between data and simulation, as well as uncertainties on the cross-sections. For data collected on the ϒ(3S) and ϒ(2S) resonances, an additional uncertainty arises due to ϒ→e+e-X background. For data collected off the ϒ resonances, we estimate an additional uncertainty due to time dependent efficiency variations, which can affect the short off-resonance runs. The relative uncertainties on the luminosities of the on-resonance (off-resonance) samples are 0.43% (0.43%) for the ϒ(4S), 0.58% (0.72%) for the ϒ(3S), and 0.68% (0.88%) for the ϒ(2S).This work is supported by the US Department of Energy and National Science Foundation, the Natural Sciences and Engineering Research Council (Canada), the Commissariat à l’Energie Atomique and Institut National de Physique Nucléaire et de Physiquedes Particules (France), the Bundesministerium für Bildung und Forschung and Deutsche Forschungsgemeinschaft (Germany), the Istituto Nazionale di Fisica Nucleare (Italy), the Foundation for Fundamental Research on Matter (The Netherlands), the Research Council of Norway, the Ministry of Education and Science of the Russian Federation, Ministerio de Ciencia e Innovación (Spain), and the Science and Technology Facilities Council (United Kingdom). Individuals have received support from the Marie-Curie IEF program (European Union) and the A.P. Sloan Foundation (USA)

The BaBar detector: Upgrades, operation and performance

Contains fulltext : 121729.pdf (preprint version ) (Open Access

Environmental influences on distribution of four Sciaenidae species (Actinopterygii, Perciformes) in a tropical bay at Southeastern Brazil

We sampled fish and measured environmental variables in the Sepetiba Bay, a tropical embayment at Southeastern Brazil. The aim was to assess environmental influences on distribution of four abundant species of Sciaenidae Micropogonias furnieri (Desmarest, 1823), Ctenosciaena gracilicirrhus (Metzelaar, 1919), Cynoscion leiarchus (Cuvier, 1830) and Menticirrhus americanus (Linnaeus, 1758) to test the habitat partition hypothesis. Samples were taken between June 1993 and July 1996, at three bay zones (outer, central and inner). Depth was the most important environmental variable to influence fish distribution, followed by transparency. M. furnieri showed significant negative correlation to depth, transparency and salinity, while C. gracilicirrhus showed the opposite situation. The highest densities of C. leiarchus occurred in the lowest temperature, while M. americanus did not showed preferences for any of the examined environmental variables. Spatial separation, mainly between M. furnieri and C. gracilicirrhus, seems to be the strategy developed to coexist in the Sepetiba Bay, with M. furnieri being more adapted to copy with harsh environmental conditions of the inner bay. The other three species, which use mostly the outer bay zone, seem to be restricted to more stable conditions, where influences from oceanic waters are more intense.<br>Foram coletados peixes e medidas as variáveis ambientais na Baía de Sepetiba, uma baía tropical do Sudeste do Brasil. O objetivo foi determinar influências ambientais na distribuição de quatro espécies abundantes de Sciaenidae Micropogonias furnieri (Desmarest, 1823), Ctenosciaena gracilicirrhus (Metzelaar,1919), Cynoscion leiarchus (Cuvier,1830) and Menticirrhus americanus (Linnaeus, 1758) para testar a hipótese de partição do hábitat. Amostragens foram feitas entre Junho de 1993 e Julho de 1996 em três zonas da baía (externa, central e interna). A profundidade foi a mais importante variável ambiental que influenciou a distribuição dos peixes, seguida pela transparência. M. furnieri mostrou uma correlação negativa significante em relação à profundidade, transparência e salinidade, enquanto C. gracilicirrhus evidenciou uma situação oposta. As maiores densidades de C. leiarchus ocorreram nas menores temperaturas, enquanto M. americanus não parece ter preferências por nenhuma das variáveis ambientais examinadas. A separação espacial, principalmente entre M. furnieri e C. gracilicirrhus, parece ser uma estratégia desenvolvida para coexistirem na Baía de Sepetiba, com M. furnieri sendo mais adaptada para suportar as condições ambientais mais difíceis da zona interna. As outras três espécies, que utilizam mais a zona externa, parecem ser restritas às mais estáveis condições, onde influências das águas oceânicas são mais intensas