We present the first measurement of associated direct photon + muon production in hadronic collisions, from a sample of 1.8 TeV $p \bar p$ collisions recorded with the Collider Detector at Fermilab. Quantum chromodynamics (QCD) predicts that these events are primarily from the Compton scattering process $cg \to c\gamma$, with the final state charm quark producing a muon. Hence this measurement is sensitive to the charm quark content of the proton. The measured cross section of $29\pm 9 pb^{-1}$ is compared to a leading-order QCD parton shower model as well as a next-to-leading-order QCD calculation.
We report on measurements of the ϒ(1S), ϒ(2S), and ϒ(3S) differential, (d2σdPtdy)y=0, and integrated cross sections in pp¯ collisions at s=1.8 TeV using a sample of 16.6 ± 0.6 pb−1 collected by the Collider Detector at Fermilab. The three resonances were reconstructed through the decay ϒ→μ+μ−. Comparison is made to a leading order QCD prediction.
We have searched for heavy neutral gauge bosons (Z′) in dielectron and dimuon decay modes using 110pb−1 of p¯p collisions at s=1.8TeV collected with the Collider Detector at Fermilab. We present a limit on the production cross section times branching ratio of a Z′ boson decaying into dileptons as a function of Z′ mass. For mass MZ′>600GeV/c2, the upper limit is 40 fb at 95% confidence level. We set the lower mass limits of 690, 590, 620, 595, 565, 630, and 600GeV/c2 for ZSM′, Zψ, Zη, Zχ, ZI, ZLR, and ZALRM, respectively.
The dilepton mass spectrum in pp¯→l+l−+X interactions is studied using dielectrons (ee) and dimuons (μμ) in 110pb−1 of data collected with the Collider Detector at Fermilab. The data are consistent with standard model predictions. The mass spectrum, being a probe for new physics, is examined for new interactions of quarks and leptons from a common composite structure. Assuming a contact interaction with the conventional coupling g02/4π=1, limits on chiral quark-electron and quark-muon compositeness scales in the range of 2.5 to 4.2 TeV are obtained.
We present measurements of correlated bb¯ cross sections, μ−μ correlations, the average B0B¯0 mixing parameter χ¯, and a limit on the CP-violating parameter εB. For these measurements, we use muon pairs from bb¯ double semileptonic decays. The data used in this analysis were taken with the Collider Detector at Fermilab and represent an integrated luminosity of 17.4±0.6 pb−1. The results concerning bb¯ production correlations are compared to predictions of next-to-leading order QCD computations.
DO has measured the inclusive production cross section of W and Z bosons in a sample of 13 pb$^{-1}$ of data collected at the Fermilab Tevatron. The cross sections, multiplied by their leptonic branching fractions, for production in pbar-p collisions at sqrt{s}=1.8 TeV are sigma_W*B(W->e nu) = 2.36+-0.02+-0.08+-0.13 nb, sigma_W*B(W->mu nu) = 2.09+-0.06+-0.22+-0.11 nb, sigma_Z*B(Z->e+ e-) = 0.218+-0.008+-0.008+-0.012 nb, and sigma_Z*B(Z->mu+ mu-) = 0.178+-0.022+-0.021+-0.009 nb, where the first uncertainty is statistical and the second systematic; the third reflects the uncertainty in the integrated luminosity. For the combined electron and muon analyses, we find sigma_W*B(W->l mu)/sigma_Z*B(Z->l+ l-) = 10.90+-0.52. Assuming standard model couplings, we use this result to determine the width of the W boson, and obtain Gamma(W) = 2.044+-0.097 GeV.
We report on measurements of the ϒ(1S), ϒ(2S), and ϒ(3S) differential cross sections (d2σ/dpTdy)|y|<0.4, as well as on the ϒ(1S) polarization in pp¯ collisions at s=1.8TeV using a sample of 77±3pb−1 collected by the collider detector at Fermilab. The three resonances were reconstructed through the decay ϒ→μ+μ−. The measured angular distribution of the muons in the ϒ(1S) rest frame is consistent with unpolarized meson production.
We present a measurement of Z0 boson and Drell-Yan production cross sections in p¯p collisions at s=1.8TeV using a sample of 107pb−1 accumulated by the Collider Detector at Fermilab. The Drell-Yan cross section is measured in the mass range of Mμμ>40GeV/c2. We compare the measurements with the predictions of quantum chromodynamics in both leading order and next-to-leading order, incorporating the recent parton distribution functions. The measurements are consistent with the standard model expectations.
We report on a search for second generation leptoquarks (Phi_2) using a data sample corresponding to an integrated luminosity of 110 pb^{-1} collected at the Collider Detector at Fermilab. We present upper limits on the production cross section as a function of Phi_2 mass, assuming that the leptoquarks are produced in pairs and decay into a muon and a quark with branching ratio beta. Using a Next-to-Leading order QCD calculation, we extract a lower mass limit of M_{\Phi_2} > 202 (160) GeV$/c^{2} at 95% confidence level for scalar leptoquarks with beta=1(0.5).
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.