The search for a Higgs boson decaying to a b¯b pair is one of the key analyses ongoing at the ATLAS experiment. Despite being the largest branching ratio decay for a Standard Model Higgs boson, a large dataset is necessary to perform this analysis because of the very large backgrounds affecting the measurement. To discriminate the electroweak H → b¯b signal from the large QCD backgrounds, the associated production of the Higgs with a W or a Z boson decaying leptonically is used. Different techniques have been proposed to enhance the signal over background ratio in the VH(b¯b) channel, from dedicated kinematic cuts, to a single large radius jet to identify the two collimated b’s in the Higgs high transverse momentum regime, to multivariate techniques. The high-pT approach, using a large radius jet to identify the b’s coming from the Higgs decay, has been tested against an analysis based on kinematic cuts for a dataset of 4.7 fb−1 luminosity at √s = 7 TeV, and compatible results were found for the same transverse momentum range. Using a kinematic cut based approach the VH(b¯b) signal search has been performed for the full LHC Run 1 dataset: 4.7 fb−1 at √s = 7 TeV and 20.7 fb−1 at √s = 8 TeV. Several backgrounds to this analysis, such as Wb¯b have not been measured in data yet, and an accurate study of the theoretical description has been performed, comparing the predictions of various Monte Carlo generators at different orders. The complexity of the analysis requires a profile likelihood fit with several categories and almost 200 parameters, taking into account all the systematics coming from experimental or modelling limitations, to extract the result. To validate the fit model, a test of the ability to extract the signal is performed on the resonant V Z(b¯b) background. A 4.8σ excess compatible with the Standard Model rate expectation has been measured, with a best fit value μVZ = 0.93+0.22−0.21. The full LHC Run1 dataset result for the VH(b¯b) process is a limit of (1.3)1.4 x SM (expected) observed, with a best fit value of 0.2±0.5(stat)±0.4(sys) for a Higgs boson of 125 GeV mass.

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Arquitetura e Urbanismo, 2008. / Submitted by Luis Felipe Souza (luis_felas@globo.com) on 2009-03-12T18:48:44Z No. of bitstreams: 1 2008_Dissertacao_LuanaKallas.pdf: 3788688 bytes, checksum: de1e2203a07ffdd8c46eea598afd839f (MD5) / Approved for entry into archive by Gomes Neide(nagomes2005@gmail.com) on 2009-03-20T17:26:15Z (GMT) No. of bitstreams: 1 2008_Dissertacao_LuanaKallas.pdf: 3788688 bytes, checksum: de1e2203a07ffdd8c46eea598afd839f (MD5) / Made available in DSpace on 2009-03-20T17:26:15Z (GMT). No. of bitstreams: 1 2008_Dissertacao_LuanaKallas.pdf: 3788688 bytes, checksum: de1e2203a07ffdd8c46eea598afd839f (MD5) / No desenho urbano, a adequação bioclimática aproveita variáveis do clima e vegetação buscando a sustentabilidade para um equilíbrio ecológico-ambiental e o conforto térmico humano no espaço urbano. Esta pesquisa estuda o desenho urbano implantado no loteamento Habitar Brasil Bid (HBB) em Teresina-PI, através de uma avaliação pósocupacional, considerando os aspectos de sustentabilidade e adequação bioclimática e mostra os inconvenientes para as características da região. São analisados os fatores que influenciam o clima urbano como o revestimento do solo, a topografia, a vegetação, o adensamento, a ventilação e a radiação solar. O clima é visto como referencial teórico assim como a cidade de Teresina e suas características climáticas. O método utilizado analisa as variáveis climáticas e a pesquisa de campo de alguns pontos do loteamento e sua relação com a estação meteorológica de referência, nos mesmos dias e horários. A pesquisa descreve que o microclima gerado no desenho urbano do loteamento contribui para um aumento de temperatura superficial e conseqüente aumento de temperatura do ar, diminui a umidade relativa do ar proporcionando um desconforto térmico humano acentuado por ocasião de calmarias existentes na região de Teresina. Ao final desta pesquisa são apresentadas algumas considerações para melhorias do espaço urbano e da qualidade ambiental do loteamento, melhorando o conforto humano _________________________________________________________________ ABSTRACT / In the urban drawing, bioclimatic adequation considers variables such as climate and vegetation trying to obtain the sustainability for an environmental – ecological equilibrium and the thermal humane comfort in the urban space. This research studies the urban drawing implemented in the land/lot division Habitar Brasil Bid Division (HBB) in the city of Teresina, in the Brazilian state of Piaui, through a post occupational evaluation considering sustainability and bioclimatic adequation aspects and shows the inconveniences due to the region’s characteristics. Factors that influence the urban climate such as land covering, topography, vegetation, densification, ventilation and solar radiation were analyzed. The climate is considered the theoretical reference, as is the city of Teresina and its climate characteristics. The method that was used analyses the climatic variables and field researches of some parts of the land/lot division and its reference meteorological stations in the same days and times. The research describes that the microclimate generated by the urban drawing result of the land/lot division contributed for the increase of the superficial temperature and, consequently an increase in the temperature of the air decreases the relative humidity resulting in a human thermal discomfort which is aggravated in the occasion of doldrums that take place in the region of Teresina. At the end of this research some considerations on the improvement of urban space and the environmental quality of the land/lot division in order to improve human comfort are made

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