120 research outputs found

    Searches for the Lightest Supersymmetric Particle at LEP2 when R-parity is violated

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    Searches for the Lightest Supersymmetric Particle (LSP) are performed under the assumption that R-parity is violated via a single dominant LLEbar, LQDbar or UbarDbarDbar coupling. Data collected by the ALEPH detector at LEP with centre-of-mass energies from 189GeV to 208GeV and a total integrated luminosity of 628pb^{-1} are used. Searches for direct and indirect decays of pair produced neutralinos and charginos are carried out. In the absence of signal, parameter space of the Minimal Supersymmetric Standard Model is constrained and limits on the mass of the LSP are obtained. Constraints from the Z width measurement, slepton, squark and Higgs searches are also used to exclude parameter space. The lower mass limits for direct decays at 95% confidence on the LSP are 60.2GeV/c^2, 42.3GeV/c^2 and 25.9GeV/c^2 for LLEbar, LQDbar and UbarDbarDbar coupling respectively. The lower mass limits for indirect decays at 95% confidence on the LSP are 58.7GeV^2, 44.2GeV^2 and 42.2GeV^2 for LLEbar, LQDbar and UbarDbarDbar coupling respectively. The limits are valid for all values of \mu, tan\beta, m_{0} and M_{2}

    Using Double Tagging to measure the Performance of the Same Side Kaon Tagger in Data

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    This note describes a method for the measurement of the wrong-tag fraction of the Same Side Kaon tagger, ωss\omega_{ss} in data using the Double Tagging procedure. The importance of such a measurement is explained and the method of Double Tagging described. This measurement was carried out using samples from reconstructed Bs>DsπBs -> Ds\pi and Bs>DsμνBs -> Ds\mu\nu decays. The impact of background in both decay channels on the measurement of ωss\omega_{ss} was also studied. A general way of handling tagger correlations is presented. Finally, the Double Tagging measurement and the correlation investigation are performed on the present Monte Carlo data and the results presented. Results show that with 2fb-1 of data, the Double Tagging procedure can be used to measure the SS Kaon wrong-tag fraction to a statistical accuracy of 3.6% and 1.2% for the Bs>DsπBs -> Ds\pi and Bs>DsμνBs -> Ds\mu\nu channels respectively

    Market Sanitation: A Case Study of Oregbeni Market Benin - City Edo State, Nigeria

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    Poor market sanitation is an intractable problem in Nigeria and has contributed to the spread of infectious diseases and environmental degradation. This study was undertaken to determine the awareness and practice of solid waste management in market places among market users. It involved 180 store owners and customers recruited from Oregbeni market in Benin City, Nigeria. They were administered questionnaires while an in depth interview was conducted with the waste managers in the market. Checklist was used to carry out observation of the market place sanitation status. The data obtained was then analyzed and compared using SPSS. The results showed that a high proportion of respondents were aware of improper waste management (133; 62.8%) and agreed (174; 96.7%) that it is associated with many risks. Despite this high level of awareness, the practice of open dumping of waste was prevalent (108; 60.0%). Interestingly, 96.1% expressed willingness to pay for an improved waste disposal system while 55.6% rated the existing system as poor. Our findings suggest therefore that there is an urgent needs to improve waste collection, and disposal at market places.Keywords: Market sanitation, Solid Waste Management, Health hazards, Environmental degradation

    Prevalence of overweight and obesity among students in private and public secondary schools in a peri-urban Nigerian town

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    Aims: To investigate the prevalence of overweight and obesity among secondary school students in Ekpoma.Study design: Cross sectional studyPlace and duration of the study: Private and public secondary schools in Ekpoma Edo state; from May to October,2011.Methodology: This is a school based analytical cross-sectional study of a sample of 417 students drawn from 4secondary schools in Ekpoma using the multistage sampling technique. Semi-structured interviewer-administeredquestionnaires were used to obtain qualitative information from the respondents; the weight of each respondent wasmeasured using a bathroom scale and the Body Mass Index (BMI) calculated and classified based on the AmericanMedical Association classification. The results obtained for students in private schools where then compared withthose of their peers in public secondary schools.Results: The prevalence of overweight and obesity was found to be 8.6% and 1% respectively; the mean BMI was19.6±2.6. More (67.5%) of those found to be overweight and obese were students in private schools (95% CI = 1.03-4.39 OR=2.11; ?2= 4.85). Similarly, 11.59% and 1.45% of students in private schools were overweight and obeserespectively compared to 5.71% and 0.95% for those in public schools. Majority (68%) of respondents had poorknowledge of the risk factors for and problems associated with being overweight or obese. Students in the uppersocial class are more likely to be overweight/obese compared to their peers in the lower social class((X 2HM = 10.35;P <.01; common odds ratio = 3)CONCLUSION: Over nutrition and under nutrition are both occurring in adolescents in a predominantly ruralsetting which suggests that Policy makers and health professionals need to implement strategies that will preventover nutrition side by side current efforts to curb under- nutrition. Reactivation of the school health program inNigeria is considered a helpful initial step

    Search for the standard model Higgs boson at LEP

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    Absolute mass lower limit for the lightest neutralino of the MSSM from e+ee^{+}e^{-} data at s\sqrt{s} up to 209 GeV

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    Charginos and neutralinos are searched for in the data collected by the ALEPH experiment at LEP for centre-of-mass energies up to 209 GeV. The negative result of these searches is combined with those from searches for sleptons and Higgs bosons to derive an absolute lower limit of 43.1 GeV/c(2) on the mass of the lightest supersymmetric particle (LSP), assumed to be the,lightest neutralino. This limit is obtained in the framework of the MSSM with R-parity conservation and with gaugino and sfermion mass unification at the GUT scale and assuming no mixing in the stau sector. The LSP limit degrades only slightly to 42.4 GeV/c(2) if stau mixing is considered. Within the more constrained framework of minimal supergravity, the limit is 50 GeV/c(2)

    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

    Search for charginos nearly mass degenerate with the lightest neutralino in e+ee^+ e^- collisions at centre-of-mass energies up to 209 GeV

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    A search for charginos nearly mass degenerate with the lightest neutralino is performed with the data collected by the ALEPH detector at LEP, at centre-of-mass energies between 189 and 209 GeV, corresponding to an integrated luminosity of 628 pb-1. The analysis is based on the detection of isolated and energetic initial state radiation photons, produced in association with chargino pairs whose decay products have little visible energy. The number of candidate events observed is in agreement with that expected from Standard Model background sources. These results are combined with those of other direct searches for charginos, and a lower limit of 88 GeV/c2 at 95 % confidence level is derived for the chargino mass in the case of heavy sfermions, irrespective of the chargino-neutralino mass difference.A search for charginos nearly mass degenerate with the lightest neutralino is performed with the data collected by the ALEPH detector at LEP, at centre-of-mass energies between 189 and 209 GeV, corresponding to an integrated luminosity of 628 pb −1 . The analysis is based on the detection of isolated and energetic initial state radiation photons, produced in association with chargino pairs whose decay products have little visible energy. The number of candidate events observed is in agreement with that expected from Standard Model background sources. These results are combined with those of other direct searches for charginos, and a lower limit of 88 GeV/ c 2 at 95% confidence level is derived for the chargino mass in the case of heavy sfermions, irrespective of the chargino-neutralino mass difference.A search for charginos nearly mass degenerate with the lightest neutralino is performed with the data collected by the ALEPH detector at LEP, at centre-of-mass energies between 189 and 209 GeV, corresponding to an integrated luminosity of 628 pb-1. The analysis is based on the detection of isolated and energetic initial state radiation photons, produced in association with chargino pairs whose decay products have little visible energy. The number of candidate events observed is in agreement with that expected from Standard Model background sources. These results are combined with those of other direct searches for charginos, and a lower limit of 88 GeV/c2 at 95 % confidence level is derived for the chargino mass in the case of heavy sfermions, irrespective of the chargino-neutralino mass difference

    Search for the Standard Model Higgs boson at LEP

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    The four LEP Collaborations, ALEPH, DELPHI, L3 and OPAL, have collected a total of 2461 pb(-1) of e(+)e(-) collision data at centre-of-mass energies between 189 and 209 GeV. The data are used to search for the Standard Model Higgs boson. The search results of the four Collaborations are combined and examined in a likelihood test for their consistency with two hypotheses: the background hypothesis and the signal plus background hypothesis. The corresponding confidences have been computed as functions of the hypothetical Higgs boson mass. A lower bound of 114.4 GeV/c(2) is established, at the 95% confidence level, on the mass of the Standard Model Higgs boson. The LEP data are also used to set upper bounds on the HZZ coupling for various assumptions concerning the decay of the Higgs boson
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