32 research outputs found

    Study of the ZZ\gamma and Z\gamma\gamma Couplings in Z(\nu\nu)\gamma Production

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    We have measured the ZZ-gamma and Z-gamma-gamma couplings by studying p-bar p -> (missing ET) gamma + X events at sqrt(s)=1.8 TeV with the D0 detector at the Fermilab Tevatron Collider. This first study of hadronic Z-gamma production in the neutrino decay channel gives the most stringent limits on anomalous couplings available. A fit to the transverse energy spectrum of the photon in the candidate event sample, based on a data set corresponding to an integrated luminosity of 13.1 pb^(-1), yields 95% CL limits on the anomalous CP-conserving ZZ-gamma couplings of |h^Z_(30)|<0.9, |h^Z_(40)|<0.21, for a form-factor scale Lambda = 500 GeV. Combining these results with our previous measurement using Z -> ee and mu-mu yields the limits:|h^Z_(30)|<0.8, |h^Z_(40)|<0.19 (Lambda = 500 GeV) and |h^Z_(30)|<0.4, |h^Z_(40)|<0.06 (Lambda = 750 GeV).Comment: 10 pages, 2 figures, 2 table

    Studies of Gauge Boson Pair Production and Trilinear Couplings

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    The gauge boson pair production processes Wg, WW, WZ, and Zg were studied using pbarp collisions corresponding to an integrated luminosity of ~14 pb-1 at a center-of-mass energy of sqrt(s) = 1.8 TeV. Analysis of Wg prod with subsequent W boson decay to lv (l=e,mu) is reported, including a fit to the pT spectrum of the photons which leads to limits on anomalous WWg couplings. A search for WW prod with subsequent decay to l-lbar-v-vbar (l=e,mu) is presented leading to an upper limit on the WW prod cross section and limits on anomalous WWg and WWZ couplings. A search for high pT W bosons in WW and WZ prod is described, where one W boson decays to an ev and the second W boson or the Z boson decays to two jets. A maximum likelihood fit to the pT spectrum of W bosons resulted in limits on anomalous WWg and WWZ couplings. A combined fit to the three data sets which provided the tightest limits on anomalous WWg and WWZ couplings is also described. Limits on anomalous ZZg and Zgg couplings are presented from an analysis of the photon ET spectrum in Zg events in the decay channels (ee, mu-mu, and v-vbar) of the Z boson.Comment: 77 Pages including 40 Figures. Submitted to PR

    Limits on Anomalous WWγWW\gamma Couplings from ppˉWγ+Xp\bar{p} \to W \gamma + X Events at s=1.8\sqrt{s}=1.8 TeV

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    We have measured the WWγWW\gamma gauge boson coupling parameters using ppˉνγ+Xp\bar{p}\to \ell\nu\gamma+X (=e,μ\ell=e,\mu) events at s=1.8\sqrt{s}=1.8 TeV. The data, corresponding to an integrated luminosity of 89.1 pb^{-1}, were collected using the D0 detector at the Fermilab Tevatron Collider. The measured cross section times branching ratio for ppˉWγ+Xp\bar{p} \to W\gamma+X with pTγp_T^\gamma > 10 GeV/c and Rγ>0.7R_{\ell\gamma} > 0.7 is 11.81.6+1.7±2.0{11.8}^{+1.7}_{-1.6} \pm 2.0 pb, in agreement with the Standard Model prediction. The one degree of freedom 95% confidence level limits on individual CP-conserving parameters are 0.98<Δκ<1.01-0.98<\Delta\kappa<1.01 and 0.33<λ<0.31-0.33<\lambda<0.31. Similar limits are set on the CP}violating coupling parameters.Comment: 10 pages, including two figures. Paper submitted to Phys. Rev. Let

    Recruitment to a physical activity intervention study in women at increased risk of breast cancer

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    <p>Abstract</p> <p>Background</p> <p>Physical activity is being studied as a breast cancer prevention strategy. Women at risk of breast cancer report interest in lifestyle modification, but recruitment to randomized physical activity intervention studies is challenging.</p> <p>Methods</p> <p>We conducted an analysis of recruitment techniques used for a prospective, randomized pilot study of physical activity in women at risk of breast cancer. We evaluated differences in proportion of eligible patients, enrolled patients, and successful patients identified by each individual recruitment method. The Fisher-Freeman-Halton test (an extension of Fisher's exact test from 2 × 2 tables to general row by column tables) was used to compare the success of different recruitment strategies.</p> <p>Results</p> <p>We received 352 inquiries from women interested in participating, of whom 171 (54%) were eligible. Ninety-nine women completed a baseline activity evaluation, and 58 (34% of eligible; 16% of total inquiries) were randomized. Recruitment methods fell into three broad categories: media techniques, direct contact with potential participants, and contacts with health care providers. Recruitment strategies differed significantly in their ability to identify eligible women (p = 0.01), and women who subsequently enrolled in the study (p = 0.02).</p> <p>Conclusion</p> <p>Recruitment techniques had varying success. Our data illustrate the challenges in recruiting to behavior modification studies, and provide useful information for tailoring future recruitment efforts for lifestyle intervention trials.</p> <p>Trial Registration No(s)</p> <p>CDR0000393790, NCI-04-C-0276, NCI-NAVY-B05-001</p

    Selective hydrogenation of multiple unsaturated compounds

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    Selective Hydrogenation of Multiple Unsaturated Compounds

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