20 research outputs found

    Search for the Flavor-Changing Neutral-Current Decays D+→π+μ+μ−D^+\to \pi^+ \mu^+ \mu^- and D+→π+e+e−D^+\to \pi^+ e^+ e^-

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    We report the results of a search for the flavor-changing neutral-current decays D+→π+μ+μ−D^+\rightarrow \pi^+ \mu^+ \mu^- and D+→π+e+e−D^+\rightarrow \pi^+ e^+ e^- in data from Fermilab charm hadroproduction experiment E791. No signal above background is found, and we obtain upper limits on branching fractions, B(D+→π+μ+μ−)<1.8×10−5B(D^+\rightarrow \pi^+ \mu^+ \mu^-) < 1.8 \times 10^{-5} and B(D+→π+e+e−)<6.6×10−5B(D^+\rightarrow \pi^+ e^+ e^-) < 6.6 \times 10^{-5}, at the 90\% confidence level.Comment: nine pages with figures; compressed, uuencoded postscrip

    Asymmetries between the production of D+ and D- mesons from 500 GeV/c pi- nucleon interactions as a function of xF and pt**2

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    We present asymmetries between the production of D+ and D- mesons in Fermilab experiment E791 as a function of xF and pt**2. The data used here consist of 74,000 fully-reconstructed charmed mesons produced by a 500 GeV/c pi- beam on C and Pt foils. The measurements are compared to results of models which predict differences between the production of heavy-quark mesons that have a light quark in common with the beam (leading particles) and those that do not (non-leading particles). While the default models do not agree with our data, we can reach agreement with one of them, PYTHIA, by making a limited number of changes to parameters used

    Mass Splitting and Production of Σc0\Sigma_c^0 and Σc++\Sigma_c^{++} Measured in 500GeV500 {GeV} π−−\pi^- -N Interactions

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    From a sample of 2722±782722 \pm 78 Λc+\Lambda_c^+ decaying to the pK−π+pK^-\pi^+ final state, we have observed, in the hadroproduction experiment E791 at Fermilab, 143±20143 \pm 20 Σc0\Sigma_c^0 and 122±18122 \pm 18 Σc++\Sigma_c^{++} through their decays to Λc+π±\Lambda_c^+ \pi^{\pm}. The mass difference M(Σc0)−M(Λc+M(\Sigma_c^0) - M(\Lambda_c^+) is measured to be (167.38±0.29±0.15)MeV(167.38\pm 0.29\pm 0.15) {MeV}; for M(Σc++)−M(Λc+)M(\Sigma_c^{++}) - M(\Lambda_c^+), we find (167.76±0.29±0.15)MeV(167.76\pm 0.29\pm0.15) {MeV}. The rate of Λc+\Lambda_c^+ production from decays of the Σc\Sigma_c triplet is (22\pm 2\pm 3) {%} of the total Λc+\Lambda_c^+ production assuming equal rate of production from all three, as measured for Σc0\Sigma_c^0 and Σc++\Sigma_c^{++}. We do not observe a statistically significant Σc\Sigma_c baryon-antibaryon production asymmetry. The xFx_F and pt2p_t^2 spectra of Λc+\Lambda_c^+ from Σc\Sigma_c decays are observed to be similar to those for all Λc+\Lambda_c^+'s produced.Comment: 15 pages, uuencoded postscript 3 figures uuencoded, tar-compressed fil

    Prevalence of obesity in preschool Greek children, in relation to parental characteristics and region of residence

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    <p>Abstract</p> <p>Background</p> <p>The aim of this retrospective cohort study was to record the prevalence of overweight and obesity in relation to parental education level, parental body mass index and region of residence, in preschool children in Greece.</p> <p>Methods</p> <p>A total of 2374 children (1218 males and 1156 females) aged 1–5 years, stratified by parental educational level (Census 1999), were examined from 105 nurseries in five counties, from April 2003 to July 2004, Weight (kg) and height (cm) were obtained and BMI (kg/m<sup>2</sup>) was calculated. Both the US Centers for Disease Control (CDC) and the International Obesity Task Force (IOTF) methods were used to classify each child as "normal", "at risk of overweight" and "overweight". Parental demographic characteristics, such as age and educational level and parental anthropometrical data, such as stature and body weight, were also recorded with the use of a specifically designed questionnaire.</p> <p>Results</p> <p>The overall estimates of at risk of overweight and overweight using the CDC method was 31.9%, 10.6 percentage points higher than the IOTF estimate of 21.3% and this difference was significant (p < 0.001). Children with one obese parent had 91% greater odds for being overweight compared to those with no obese parent, while the likelihood for being overweight was 2.38 times greater for children with two obese parents in the multivariate model.</p> <p>Conclusion</p> <p>Both methods used to assess prevalence of obesity have demonstarted that a high percentage of the preschool children in our sample were overweight. Parental body mass index was also shown to be an obesity risk factor in very young children.</p
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