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

Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02

Plasma gut hormone levels in 37 patients with pheochromocytomas

Pheochromocytomas are usually recognized by the effects of overproduction of catecholamines, but there are clinical features that cannot be ascribed to catecholamine excess that may be due to vasoactive peptides. We, therefore, measured blood levels of vasoactive intestinal peptides (VIP), substance P, somatostatin (SS), and motilin in 50 instances in 37 patients with pheochromocytomas-21 malignant, 10 benign intra-adrenal, and 6 ectopic (5 paracardial and 1 perirenal). Hormone levels were considered raised if the level was more than 3 S.D. above the mean value found in 52 healthy subjects. Of the 37 patients, 20 (54%) had an abnormality in 1 or more gut hormone levels. The most common abnormality was a raised SS in 9/37 (24%). In addition to these, however, 3 (8%) others had raised VIP, 5 (13.5%) raised motilin, and 3 (8%) raised substance P. Patients with benign adrenal adenomas had raised levels of SS and substance P. Ectopic pheochromocytomas produced only SS in addition to catecholamines, but malignant pheochromocytomas could secrete all 4 peptides, and more than 1 in the same patient. We conclude that pheochromocytomas may secrete multiple vasoactive peptides, and they are more likely to do so if malignant. Somatostatin is the most commonly secreted peptide and is found with benign adrenal and ectopic (paracardiac) tumors. If the level of more than 1 peptide is elevated, the likelihood of malignancy is significantly increased . Les phéochromocytomes sont généralement déceléspar les effets dûs à la surproduction de catécholamines, mais certains troubles ne peuvent être attribués à ce phénomène et relèvent peut être de l'action de peptides vasoactifs. Les auteurs se sont donc attachés à doser dans le sang le VIP, la substance P, la somatostatine (SS), et la motiline. Ces dosages furent pratiqués 50 fois chez 37 malades porteurs de phéochromocytomes: 21 malins, 10 bénins et 6 ectopiques (5 paracardiaque et 1 péri-rénal). Les taux des hormones furent considérés comme élevés lorsque leur niveau fut supérieur à plus de 3 fois le taux de 52 sujets sains. Sur les 37 malades 20 (54%) présentaient un excès d'une ou de plusieurs hormones digestives. L'anomalie constatée la plus fréquente fut l'élévation de la SS (9 fois sur 37 soit 24%). Ajoutée à ce fait fut l'élévation de la VIP chez 3 sujets (8%), de la motiline chez 5 (13.5%) et de la substance P chez 3 (8%). Les phéochromocytomes bénins surrénaliens présentaient à la fois une élévation du taux de la SS et de la substance P. Les phéochromocytomes ectopiques en revanche présentaient seulement une élévation de la SS. Les phéochromocytomes malins pouvaient sécréter les 4 peptides ou plus d'un chez le même malade. En conclusion les phéochromocytomes peuvent secréter de multiples peptides vasoactifs et plus particulièrement lorsqu'ils sont malins. La SS est la substance qui est la plus souvent secrétée et elle est trouvée dans les tumeurs bénignes surrénaliennes ou ectopiques. Si plus d'une de ces substances est produite en excès les risques de malignité de la tumeur sont significativement plus importants. Los feocromocitomas generalmente son diagnosticados por los efectos del exceso de producción de catecolaminas pero hay características clínicas que no pueden ser atribuidas al exceso de catecolaminas y que pueden ser más bien manifestación de péptidos vasoactivos. Hemos establecido los niveles sanguíneos del péptido intestinal vasoactivo (VIP), de la sustancia P, de la somatostatina (SS), y de la motilina en 50 determinaciones en 37 pacientes con feocromocitomas; 21 malignos, 10 benignos intra-adrenales, y 6 ectópicos (5 paracardiales y 1 perirrenal). Se consideró que los niveles hormonales estaban elevados cuando el nivel era de más de 3 de desviación estandar sobre el valor promedio en 52 individuos normales. De 37 pacientes, 20 (54%) presentaron un valor anormal en 1 o más determinaciones del nivel de hormonas intestinales. La anormalidad más común fue la elevación de la SS en 9/37 (24%). Además de esto, sinembargo, otros 3 (8%) presentaban elevación de VIP, 5 (13.5%) elevación de sustancia P. Los adenomas suprarrenales benignos exhibieron niveles elevados de SS y de sustancia P. Los feocromocitomas ectópicos demostraron producción sólo de SS además de catecolaminas, pero los feocromocitomas malignos demostraron ser capaces de secretar todos los 4 péptidos, y más de 1 en el mismo paciente. Hemos llegado a la conclusión de que los feocromocitomas pueden secretar múltiples peptidos vasoactivos y que ésto tiende a ocurrir cuando son malignos. La SS es el péptido más frecuentemente secretado y se lo encuentra en los tumores suprarrenales benigno y ectópico (paracardiacos). Si se encuentran niveles elevados de más de 1 péptido, la posibilidad de malignidad aparece significativamente aumentada.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41274/1/268_2005_Article_BF01655534.pd

Evidence for the associated production of a W boson and a top quark in ATLAS at √s = 7 TeV

Contains fulltext : 103353.pdf (preprint version ) (Open Access

Search for supersymmetry in events with photons, bottom quarks, and missing transverse momentum in proton-proton collisions at a centre-of-mass energy of 7 TeV with the ATLAS detector

Contains fulltext : 111247.pdf (preprint version ) (Open Access

Search for displaced muonic lepton jets from light Higgs boson decay in proton-proton collisions at s=7\sqrt{s}=7 TeV with the ATLAS detector

A search is performed for collimated muon pairs displaced from the primary vertex produced in the decay of long-lived neutral particles in proton-proton collisions at sqrt(s) = 7 TeV centre-of-mass energy, with the ATLAS detector at the LHC. In a 1.9 fb-1 event sample collected during 2011, the observed data are consistent with the Standard Model background expectations. Limits on the product of the production cross section and the branching ratio of a Higgs boson decaying to hidden-sector neutral long-lived particles are derived as a function of the particles' mean lifetime

Search for the Higgs boson in the H→WW→ℓνH\rightarrow WW \rightarrow \ell\nujj decay channel at s=7\sqrt{s}=7 TeV with the ATLAS detector

A search for the Standard Model Higgs boson has been performed in the H -> WW -> lvjj channel using 4.7 fb(-1) of pp collision data recorded at a centre-of-mass energy of root s = 7 TeV with the ATLAS detector at the Large Hadron Collider. Higgs boson candidates produced in association with zero, one or two jets are included in the analysis to maximize the acceptance for both gluon fusion and weak boson fusion Higgs boson production processes. No significant excess of events is observed over the expected background and limits on the Higgs boson production cross section are derived for a Higgs boson mass in the range 300 GeV WW produced in association with zero or one jet is 2.2 pb (1.9 pb), corresponding to 1.9 (1.6) times the Standard Model prediction. In the Higgs boson plus two jets channel, which is more sensitive to the weak boson fusion process, the observed (expected) 95% confidence level upper bound on the cross section for H -> WW production with m(H) = 400 GeV is 0.7 pb (0.6 pb), corresponding to 7.9 (6.5) times the Standard Model prediction. (C) 2012 CERN