Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

Measurement of the correlation between flow harmonics of different order in lead-lead collisions at √sNN = 2.76 TeV with the ATLAS detector

Correlations between the elliptic or triangular flow coefficients vm (m=2 or 3) and other flow harmonics vn (n=2 to 5) are measured using √sNN=2.76 TeV Pb+Pb collision data collected in 2010 by the ATLAS experiment at the LHC, corresponding to an integrated luminosity of 7 μb−1. The vm−vn correlations are measured in midrapidity as a function of centrality, and, for events within the same centrality interval, as a function of event ellipticity or triangularity defined in a forward rapidity region. For events within the same centrality interval, v3 is found to be anticorrelated with v2 and this anticorrelation is consistent with similar anticorrelations between the corresponding eccentricities, ε2 and ε3. However, it is observed that v4 increases strongly with v2, and v5 increases strongly with both v2 and v3. The trend and strength of the vm−vn correlations for n=4 and 5 are found to disagree with εm−εn correlations predicted by initial-geometry models. Instead, these correlations are found to be consistent with the combined effects of a linear contribution to vn and a nonlinear term that is a function of v22 or of v2v3, as predicted by hydrodynamic models. A simple two-component fit is used to separate these two contributions. The extracted linear and nonlinear contributions to v4 and v5 are found to be consistent with previously measured event-plane correlations

Search for vectorlike B quarks in events with one isolated lepton, missing transverse momentum, and jets at √s = 8 TeV with the ATLAS detector

A search has been performed for pair production of heavy vectorlike down-type (B) quarks. The analysis explores the lepton-plus-jets final state, characterized by events with one isolated charged lepton (electron or muon), significant missing transverse momentum, and multiple jets. One or more jets are required to be tagged as arising from b quarks, and at least one pair of jets must be tagged as arising from the hadronic decay of an electroweak boson. The analysis uses the full data sample of pp collisions recorded in 2012 by the ATLAS detector at the LHC, operating at a center-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 20.3 fb −1 . No significant excess of events is observed above the expected background. Limits are set on vectorlike B production, as a function of the B branching ratios, assuming the allowable decay modes are B → Wt/Zb/Hb. In the chiral limit with a branching ratio of 100% for the decay B → Wt, the observed (expected) 95% C.L. lower limit on the vectorlike B mass is 810 GeV (760 GeV). In the case where the vectorlike B quark has branching ratio values corresponding to those of an SU(2) singlet state, the observed (expected) 95% C.L. lower limit on the vectorlike B mass is 640 GeV (505 GeV). The same analysis, when used to investigate pair production of a colored, charge 5/3 exotic fermion T 5/3 , with subsequent decay T 5/3 → Wt, sets an observed (expected) 95% C.L. lower limit on the T 5/3 mass of 840 GeV (780 GeV)

A search for prompt lepton-jets in pp collisions at root s=8 TeV with the ATLAS detector

A search is presented for a new, light boson with a mass of about 1 GeV and decaying promptly to jets of collimated electrons and/or muons (lepton-jets). The analysis is performed with 20.3 fb−1 of data collected by the ATLAS detector at the Large Hadron Collider in proton-proton collisions at a centre-of-mass energy of 8 TeV. Events are required to contain at least two lepton-jets. This study finds no statistically significant deviation from predictions of the Standard Model and places 95% confidence-level upper limits on the contribution of new phenomena beyond the SM, incuding SUSY-portal and Higgs-portal models, on the number of events with lepton-jets.We acknowledge the support of ANPCyT, Argentina; YerPhI, Armenia; ARC, Australia; BMWFW and FWF, Austria; ANAS, Azerbaijan; SSTC, Belarus; CNPq and FAPESP, Brazil; NSERC, NRC and CFI, Canada; CERN; CONICYT, Chile; CAS, MOST and NSFC, China; COLCIENCIAS, Colombia; MSMT CR, MPO CR and VSC CR, Czech Republic; DNRF, DNSRC and Lundbeck Foundation, Denmark; IN2P3-CNRS, CEADSM/IRFU, France; GNSF, Georgia; BMBF, HGF, and MPG, Germany; GSRT, Greece; RGC, Hong Kong SAR, China; ISF, I-CORE and Benoziyo Center, Israel; INFN, Italy; MEXT and JSPS, Japan; CNRST, Morocco; FOM and NWO, Netherlands; RCN, Norway; MNiSW and NCN, Poland; FCT, Portugal; MNE/IFA, Romania; MES of Russia and NRC KI, Russian Federation; JINR; MESTD, Serbia; MSSR, Slovakia; ARRS and MIZ. S, Slovenia; DST/NRF, South Africa; MINECO, Spain; SRC and Wallenberg Foundation, Sweden; SERI, SNSF and Cantons of Bern and Geneva, Switzerland; MOST, Taiwan; TAEK, Turkey; STFC, United Kingdom; DOE and NSF, United States of America. In addition, individual groups and members have received support from BCKDF, the Canada Council, CANARIE, CRC, Compute Canada, FQRNT, and the Ontario Innovation Trust, Canada; EPLANET, ERC, FP7, Horizon 2020 and Marie Sklodowska-Curie Actions, European Union; Investissements d'Avenir Labex and Idex, ANR, Region Auvergne and Fondation Partager le Savoir, France; DFG and AvH Foundation, Germany; Herakleitos, Thales and Aristeia programmes co-financed by EU-ESF and the Greek NSRF; BSF, GIF and Minerva, Israel; BRF, Norway; the Royal Society and Leverhulme Trust, United Kingdom

Measurement of jet charge in dijet events from √s = 8 TeV pp collisions with the ATLAS detector

The momentum-weighted sum of the charges of tracks associated to a jet is sensitive to the charge of the initiating quark or gluon. This paper presents a measurement of the distribution of momentum-weighted sums, called jet charge, in dijet events using 20.3 fb−¹ of data recorded with the ATLAS detector at √s = 8 TeV in pp collisions at the LHC. The jet charge distribution is unfolded to remove distortions from detector effects and the resulting particle-level distribution is compared with several models. The pT dependence of the jet charge distribution average and standard deviation are compared to predictions obtained with several leading-order and next-to-leading-order parton distribution functions. The data are also compared to different Monte Carlo simulations of QCD dijet production using various settings of the free parameters within these models. The chosen value of the strong coupling constant used to calculate gluon radiation is found to have a significant impact on the predicted jet charge. There is evidence for a pT dependence of the jet charge distribution for a given jet flavor. In agreement with perturbative QCD predictions, the data show that the average jet charge of quark-initiated jets decreases in magnitude as the energy of the jet increases

Search for the production of single vector-like and excited quarks in the Wt final state in pp collisions at √s=8 TeV with the ATLAS detector

A search for vector-like quarks and excited quarks in events containing a top quark and a W boson in the final state is reported here. The search is based on 20.3 fb−1 of proton-proton collision data taken at the LHC at a centre-of-mass energy of 8 TeV recorded by the ATLAS detector. Events with one or two leptons, and one, two or three jets are selected with the additional requirement that at least one jet contains a b-quark. Single-lepton events are also required to contain at least one large-radius jet from the hadronic decay of a high-pTW boson or a top quark. No significant excess over the expected background is observed and upper limits on the cross-section times branching ratio for different vector-like quark and excited-quark model masses are derived. For the excited-quark production and decay to Wt with unit couplings, quarks with masses below 1500 GeV are excluded and coupling-dependent limits are set

Avaliação econômica da terminação de bovinos de corte em pastagem irrigada

Foi avaliada a viabilidade econômica de três sistemas de produção por meio da mensuração dos custos de produção e da análise dos indicadores financeiros. Os três sistemas (S1, S2 e S3), situados na fronteira oeste do Rio Grande do Sul, foram avaliados no período de outubro de 2010 a outubro de 2011. A pastagem estabelecida no S1 foi de azevém (Lolium multiflorumLam)e trevo branco (Trifolium repensLam); no S2, trevo branco, trevo vermelho (Trifolium pratenseLam), cornichão (Lotus corniculatusLam), azevém e aveia preta (Avena strigosaSchreb); e no S3, azevém, cornichão, trevo branco e trevo vermelho. Os animais foram pesados na entrada e na saída das pastagens. A coleta de dados para mensuração do custo foi realizada mensalmente utilizando-se planilhas apropriadas. As produtividades foram de 369, 772 e 637kg/ha para os sistemas S1, S2 e S3, respectivamente. O S2 apresentou o maior custo total (R$2.101,59/ha), enquanto o menor foi obtido pelo S1 (R$ 1.626,93/ha). Na análise do custo operacional médio dos três sistemas, os itens que apresentaram maiores valores foram a implantação de pastagem, a energia elétrica, a manutenção da pastagem e a depreciação. Quanto às margens, os sistemas S1, S2 e S3 apresentaram, respectivamente, R$33,46, 1.162,55 e 701,01/ha para margem bruta; R$ -63,51, 955,40 e 541,05/ha para margem operacional; e R$ -583,18, 291,61 e -28,99/ha para lucro total. A rentabilidade foi de -0,47, 4,37 e 3,01% e a lucratividade foi de -5,94, 39,92 e 27,38% para o S1, S2 e S3, respectivamente. A irrigação de pastagens para terminação de bovinos é viável economicamente, no entanto a sua adoção deve sempre visar a altas produtividades zootécnicas devido ao seu elevado custo de produção

Rotavirus associated diarrhoea during infancy in the city of S. Luís (MA), Brazil: a two-year longitudinal study

A total of 479 diarrhoeic children and 337 children without diarrhoea (controls) less than 5 years old were investigated in a two-year study in the city of S. Luís (MA), with the purpose to determine the incidence, the age distribution and the seasonality of rotaviruses, as well as to establish the severity of the disease in this region between the North and the Northeast of Brazil. rotavirus incidence was highest in children of the 1st. year of life, showing an average of 25% per year among the diarrhoeic patients attending the two main hospitals and three health units at the periphery of the city. It was shown that rotaviruses are significant enteropathogens in children less than 18 months old. Frequency of rotaviruses droped in diarrhoeic patients 18 to 23 months old to only 4%, the same percentage observed in children of the control group. A typical seasonal distribution of rotaviruses was not seen during the two years of study. There was a peak in the incidence of rotaviruses in 1986, during the rainy season, and two peaks in 1987, one in the rainy season and one in the dry season. It was also shown that severity of diarrhoea in rotavirus positive cases was higher than in the negative cases. Rotavirus diarrhoeic patients had more loose stools per day, and higher frequencies of vomiting and fever, resulting more often (> 2 times) in moderate or severe dehydration. Finally, it is concluded that the introduction of immunoprophylaxis may reduce significantly the high mortality rates in early childhood observed in S. Luís.Um total de 479 casos de diarréia aguda e de 337 crianças sem diarréia (controles) foi investigado em um estudo longitudinal de 2 anos na cidade de São Luís (MA) em crianças menores de 5 anos de idade, a fim de estabelecer a incidência e a distribuição etária e sazonal de rotavírus, bem como determinar a severidade da doença nesta região do Brasil. A incidência de Rotavírus apresentou os maiores índices durante o primeiro ano de vida das crianças, com média anual de 25% entre os pacientes atendidos nos principais hospitais pediátricos da cidade e em Unidades de Saúde da periferia. O estudo mostrou que a relevância dos rotavírus como agentes etiológicos da diarréia aguda na infância já acaba aos 18 meses de idade das crianças desta região, quando os valores de positividade caem a apenas 4%, como no grupo controle. A distribuição bimensal de rotavírus não apresentou perfil tipicamente sazonal, ocorrendo 1 pico de incidência no ano de 1986, durante a estação chuvosa, e 2 picos no ano de 1987, dos quais um na estação chuvosa e outro, durante a época seca do ano. O estudo também mostrou que a doença diarreica é mais severa entre os casos positivos para rotavírus do que entre negativos, apresentando maior freqüência de evacuações diárias, de vômitos e febre, levando ao índice acima de 2 vezes maior de casos de desidratação moderada ou severa. Finalmente, é feita uma análise em relação ao efeito que a imunoprofilaxia poderá ter sobre os elevados índices de mortalidade infantil registrados nesta região do país