Limits on WWZ and WW\gamma couplings from p\bar{p}\to e\nu jj X events at \sqrt{s} = 1.8 TeV

We present limits on anomalous WWZ and WW-gamma couplings from a search for WW and WZ production in p-bar p collisions at sqrt(s)=1.8 TeV. We use p-bar p -> e-nu jjX events recorded with the D0 detector at the Fermilab Tevatron Collider during the 1992-1995 run. The data sample corresponds to an integrated luminosity of 96.0+-5.1 pb^(-1). Assuming identical WWZ and WW-gamma coupling parameters, the 95% CL limits on the CP-conserving couplings are -0.33<lambda<0.36 (Delta-kappa=0) and -0.43<Delta-kappa<0.59 (lambda=0), for a form factor scale Lambda = 2.0 TeV. Limits based on other assumptions are also presented.Comment: 11 pages, 2 figures, 2 table

Zgamma Production in pbarp Collisions at sqrt(s)=1.8 TeV and Limits on Anomalous ZZgamma and Zgammagamma Couplings

We present a study of Z +gamma + X production in p-bar p collisions at sqrt{S}=1.8 TeV from 97 (87) pb^{-1} of data collected in the eegamma (mumugamma) decay channel with the D0 detector at Fermilab. The event yield and kinematic characteristics are consistent with the Standard Model predictions. We obtain limits on anomalous ZZgamma and Zgammagamma couplings for form factor scales Lambda = 500 GeV and Lambda = 750 GeV. Combining this analysis with our previous results yields 95% CL limits |h{Z}_{30}| < 0.36, |h{Z}_{40}| < 0.05, |h{gamma}_{30}| < 0.37, and |h{gamma}_{40}| < 0.05 for a form factor scale Lambda=750 GeV.Comment: 17 Pages including 2 Figures. Submitted to PR

A Measurement of the W Boson Mass

We report a measurement of the W boson mass based on an integrated luminosity of 82 pb$^{-1}$ from \ppbar collisions at $\sqrt{s}=1.8$ TeV recorded in 1994--1995 by the \Dzero detector at the Fermilab Tevatron. We identify W bosons by their decays to $e\nu$ and extract the mass by fitting the transverse mass spectrum from 28,323 W boson candidates. A sample of 3,563 dielectron events, mostly due to Z to ee decays, constrains models of W boson production and the detector. We measure \mw=80.44\pm0.10(stat)\pm0.07(syst)~GeV. By combining this measurement with our result from the 1992--1993 data set, we obtain \mw=80.43\pm0.11 GeV.Comment: 11 pages, 5 figure

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

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

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

We have measured the $WW\gamma$ gauge boson coupling parameters using $p\bar{p}\to \ell\nu\gamma+X$ ($\ell=e,\mu$) events at $\sqrt{s}=1.8$ 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 $p\bar{p} \to W\gamma+X$ with $p_T^\gamma$ > 10 GeV/c and $R_{\ell\gamma} > 0.7$ is ${11.8}^{+1.7}_{-1.6} \pm 2.0$ pb, in agreement with the Standard Model prediction. The one degree of freedom 95% confidence level limits on individual CP-conserving parameters are $-0.98<\Delta\kappa<1.01$ and $-0.33<\lambda<0.31$. Similar limits are set on the CP}violating coupling parameters.Comment: 10 pages, including two figures. Paper submitted to Phys. Rev. Let

Studies of Gauge Boson Pair Production and Trilinear Couplings

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

Search for the Trilepton Signature from the Associated Production of SUSY Chi_1^(+-) Chi_2^0 Gauginos

We report on a search for the trilepton signature from the associated production of supersymmetric gaugino pairs, Chi_1^(+-) Chi_2^0, within the context of minimal supersymmetric models that conserve R-parity. This search uses 95 pb^-1 of data taken with the \D0 detector at Fermilab's Tevatron collider at \sqrt{s} = 1.8 TeV. No evidence of a trilepton signature has been found, and a limit on the production cross section times branching fraction to trileptons as a function of Chi_1^(+-) mass is given.Comment: 16 pages, Latex (uses REVTeX V 3.0 style file), submitted to PR