473 research outputs found

    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

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    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 D*+/- meson production in jets from pp collisions at sqrt(s) = 7 TeV with the ATLAS detector

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    This paper reports a measurement of D*+/- meson production in jets from proton-proton collisions at a center-of-mass energy of sqrt(s) = 7 TeV at the CERN Large Hadron Collider. The measurement is based on a data sample recorded with the ATLAS detector with an integrated luminosity of 0.30 pb^-1 for jets with transverse momentum between 25 and 70 GeV in the pseudorapidity range |eta| < 2.5. D*+/- mesons found in jets are fully reconstructed in the decay chain: D*+ -> D0pi+, D0 -> K-pi+, and its charge conjugate. The production rate is found to be N(D*+/-)/N(jet) = 0.025 +/- 0.001(stat.) +/- 0.004(syst.) for D*+/- mesons that carry a fraction z of the jet momentum in the range 0.3 < z < 1. Monte Carlo predictions fail to describe the data at small values of z, and this is most marked at low jet transverse momentum.Comment: 10 pages plus author list (22 pages total), 5 figures, 1 table, matches published version in Physical Review

    Search for supersymmetry with a dominant R-parity violating LQDbar couplings in e+e- collisions at centre-of-mass energies of 130GeV to 172 GeV

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    A search for pair-production of supersymmetric particles under the assumption that R-parity is violated via a dominant LQDbar coupling has been performed using the data collected by ALEPH at centre-of-mass energies of 130-172 GeV. The observed candidate events in the data are in agreement with the Standard Model expectation. This result is translated into lower limits on the masses of charginos, neutralinos, sleptons, sneutrinos and squarks. For instance, for m_0=500 GeV/c^2 and tan(beta)=sqrt(2) charginos with masses smaller than 81 GeV/c^2 and neutralinos with masses smaller than 29 GeV/c^2 are excluded at the 95% confidence level for any generation structure of the LQDbar coupling.Comment: 32 pages, 30 figure

    Search for supersymmetry in final states with jets, missing transverse momentum and one isolated lepton in sqrt{s} = 7 TeV pp collisions using 1 fb-1 of ATLAS data

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    We present an update of a search for supersymmetry in final states containing jets, missing transverse momentum, and one isolated electron or muon, using 1.04 fb^-1 of proton-proton collision data at sqrt{s} = 7 TeV recorded by the ATLAS experiment at the LHC in the first half of 2011. The analysis is carried out in four distinct signal regions with either three or four jets and variations on the (missing) transverse momentum cuts, resulting in optimized limits for various supersymmetry models. No excess above the standard model background expectation is observed. Limits are set on the visible cross-section of new physics within the kinematic requirements of the search. The results are interpreted as limits on the parameters of the minimal supergravity framework, limits on cross-sections of simplified models with specific squark and gluino decay modes, and limits on parameters of a model with bilinear R-parity violation.Comment: 18 pages plus author list (30 pages total), 9 figures, 4 tables, final version to appear in Physical Review

    Reducing heterotic M-theory to five dimensional supergravity on a manifold with boundary

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    This paper constructs the reduction of heterotic MM-theory in eleven dimensions to a supergravity model on a manifold with boundary in five dimensions using a Calabi-Yau three-fold. New results are presented for the boundary terms in the action and for the boundary conditions on the bulk fields. Some general features of dualisation on a manifold with boundary are used to explain the origin of some topological terms in the action. The effect of gaugino condensation on the fermion boundary conditions leads to a `twist' in the chirality of the gravitino which can provide an uplifting mechanism in the vacuum energy to cancel the cosmological constant after moduli stabilisation.Comment: 16 pages, RevTe

    A description of patients with recurrence of pulmonary tuberculosis in TB hospital, Ermelo

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    Thesis (MMed)--Stellenbosch University, 2015.South Africa is one of the high burden countries for TB in Sub Sahara in Africa with Mpumalanga as one of the provinces with a high burden of disease. Data available on tuberculosis in Msukaligwa indicate the following: Cure Rate 40%; Smear conversion at the end of intensive phase 35% and Defaulter Rate 27.5%. The problem of TB is made worse by the twin epidemic of HIV, with a prevalence of 38.9% in our district -the highest among the 3 districts in the province. Retreatment TB carries the risk of developing TB drug resistance with severe consequences for the patient and the population. Understanding the characteristics of these patients will help in designing interventions to prevent the problem, promote a high cure rate for patients with TB in our health care system and reduce to minimum the burden of re-treatment pulmonary TB on our health care facilities and community. One critical precondition for Retreatment TB is non adherence to TB treatment. Factors responsible for non adherence could be classified as individual patient factors; Co-morbid conditions; Health system; treatment related and Community factors. The outcomes of Retreatment TB could be, cure, and death and failure of treatment leading to drug resistance. The Setting of this study is the 58-bedded TB hospital in Ermelo. The Aim of the study was to describe the occurrence, characteristics and management outcome of Retreatment Pulmonary Tuberculosis in patients in the Ermelo TB hospital. The specific Objectives were to describe the socio-demographic, behavioural and clinical factors related to recurrence of the TB in patients; to determine the contribution of non adherence to treatment on recurrence of TB in the study population; to identify the prevalence of resistance to TB medication among patients with Retreatment TB ; to identify treatment outcomes in patients who have been followed up for the duration of Retreatment TB and finally to make recommendations to the Department of Health, Mpumalanga towards minimizing Retreatment TB and improving the overall TB programme. The Study design is cross sectional and descriptive; the study population comprised of patients admitted with TB at Ermelo TB hospital aged 15 years and older between 1 January 2005 and 31 December 2007.No specific probability sampling was applied in the selection of the patients. Data Collection involved visits to the TB hospital during the period and extracting the relevant information from the patient medical records and the TB register using a predesigned data collection form. Data analysis was done by the statistician from the Centre for Statistical Consultation, University of Stellenbosch. Being a descriptive study, the data analysis expresses the prevalence of various factors associated with retreatment TB. This study met the Ethical approval of the University of Stellenbosch as well as the Research Ethics Committee of the Department of Health & Social Services, Mpumalanga. Findings All the three hundred and eighty eight patient records with retreatment TB forming 19.6% of TB patients admitted between 2005 and 2007 were reviewed. The distributions of the patients were: males 66%; mean age of 41.4 years; females 34%; mean age 35.3 years. They were mostly unemployed; primary education 93%; unmarried 43% and married 34%.Retreatment TB was diagnosed with sputum smear microscopy in 71% with bacilli load of 3+ in 45%.The sources of referral to TB hospital were: public hospital 71 %; private doctors 2%. 74% of the patients have had TB 1-3 years before the episode under study. Retreatment TB categories were: after treatment completed 69%; default 19%; after cure 8% and treatment failure 4%. 98% of patients tested had +ve HIV status; the median CD4 cell count was 106 cells/µl at the time of retreatment; very few (5%) were on ART. Drug resistance to primary TB drugs was as follows: Rifampicin 16%; Isoniazid 29%; Ethambutol 19% and Streptomycin 23%. The treatment outcomes for those whom data were available were: successful 49.1%, death 23.8%; treatment default 22.9%. MDR-TB complicated 3.3% of the patients. Conclusion: Majority of the retreatment TB patients were males with an average age of 41years and unemployed. More than two thirds of the patient had completed TB treatment previously and default on treatment accounted for less than one quarter of retreatment categories. The process of care was better in terms of diagnosis of TB with sputum smear. Improvement in the documentation of key factors like smoking, alcohol, drug use among patients and co-morbidity as well as counselling and testing for HIV and provision of ARTs is required. Treatment outcomes with regards to successful outcome need to be monitored and improved upon.AFRIKAANSE OPSOMMING: Geen opsomming beskikbaa

    Measurement of tau polarization in W->taunu decays with the ATLAS detector in pp collisions at sqrt(s) = 7 TeV

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    In this paper, a measurement of tau polarization in W->taunu decays is presented. It is measured from the energies of the decay products in hadronic tau decays with a single final state charged particle. The data, corresponding to an integrated luminosity of 24 pb^-1, were collected by the ATLAS experiment at the Large Hadron Collider in 2010. The measured value of the tau polarization is Ptau = -1.06 +/- 0.04 (stat) + 0.05 (syst) - 0.07 (syst), in agreement with the Standard Model prediction, and is consistent with a physically allowed 95% CL interval [-1,-0.91]. Measurements of tau polarization have not previously been made at hadron colliders.Comment: 10 pages plus author list (25 pages total), 4 figures, 4 tables, revised author list, matches published EPJC versio

    Constraints on anomalous QGC's in e+ee^{+}e^{-} interactions from 183 to 209 GeV

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    The acoplanar photon pairs produced in the reaction e(+) e(-) - → vvyy are analysed in the 700 pb(-1) of data collected by the ALEPH detector at centre-of-mass energies between 183 and 209 GeV. No deviation from the Standard Model predictions is seen in any of the distributions examined. The resulting 95% C.L. limits set on anomalous QGCs, a(0)(Z), a(c)(Z), a(0)(W) and a(c)(W), are -0.012 lt a(0)(Z)/Lambda(2) lt +0.019 GeV-2, -0.041 lt a(c)(Z)/Lambda(2) lt +0.044 GeV-2, -0.060 lt a(0)(W)/Lambda(2) lt +0.055 GeV-2, -0.099 lt a(c)(W)/Lambda(2) lt +0.093 GeV-2, where Lambda is the energy scale of the new physics responsible for the anomalous couplings

    Measurement of the tau lepton lifetime

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    Measurement of Lambda polarization from Z decays

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