Search for charged Higgs decays of the top quark using hadronic tau decays

We present the result of a search for charged Higgs decays of the top quark, produced in $p\bar{p}$ collisions at $\surd s =$ 1.8 TeV. When the charged Higgs is heavy and decays to a tau lepton, which subsequently decays hadronically, the resulting events have a unique signature: large missing transverse energy and the low-charged-multiplicity tau. Data collected in the period 1992-1993 at the Collider Detector at Fermilab, corresponding to 18.7$\pm$0.7~pb$^{-1}$, exclude new regions of combined top quark and charged Higgs mass, in extensions to the standard model with two Higgs doublets.Comment: uuencoded, gzipped tar file of LaTeX and 6 Postscript figures; 11 pp; submitted to Phys. Rev.

Inclusive jet cross section in pˉp{\bar p p} collisions at s=1.8\sqrt{s}=1.8 TeV

The inclusive jet differential cross section has been measured for jet transverse energies, $E_T$, from 15 to 440 GeV, in the pseudorapidity region 0.1$\leq | \eta| \leq$0.7. The results are based on 19.5 pb$^{-1}$ of data collected by the CDF collaboration at the Fermilab Tevatron collider. The data are compared with QCD predictions for various sets of parton distribution functions. The cross section for jets with $E_T>200$ GeV is significantly higher than current predictions based on O($\alpha_s^3$) perturbative QCD calculations. Various possible explanations for the high-$E_T$ excess are discussed.Comment: 8 pages with 2 eps uu-encoded figures Submitted to Physical Review Letter

Measurement of Dijet Angular Distributions at CDF

We have used 106 pb^-1 of data collected in proton-antiproton collisions at sqrt(s)=1.8 TeV by the Collider Detector at Fermilab to measure jet angular distributions in events with two jets in the final state. The angular distributions agree with next to leading order (NLO) predictions of Quantum Chromodynamics (QCD) in all dijet invariant mass regions. The data exclude at 95% confidence level (CL) a model of quark substructure in which only up and down quarks are composite and the contact interaction scale is Lambda_ud(+) < 1.6 TeV or Lambda_ud(-) < 1.4 TeV. For a model in which all quarks are composite the excluded regions are Lambda(+) < 1.8 TeV and Lambda(-) < 1. 6 TeV.Comment: 16 pages, 2 figures, 2 tables, LaTex, using epsf.sty. Submitted to Physical Review Letters on September 17, 1996. Postscript file of full paper available at http://www-cdf.fnal.gov/physics/pub96/cdf3773_dijet_angle_prl.p

Search for New Particles Decaying to Dijets at CDF

We have used 106 pb^-1 of data collected with the Collider Detector at Fermilab to search for new particles decaying to dijets. We exclude at the 95% confidence level models containing the following new particles: axigluons and flavor universal colorons with mass between 200 and 980 GeV/c, excited quarks with mass between 80 and 570 GeV/c^2 and between 580 and 760 GeV/c^2, color octet technirhos with mass between 260 and 480 GeV/c^2, W' bosons with mass between 300 and 420 GeV/c^2, and E_6 diquarks with mass between 290 and 420 GeV/c^2.Comment: 18 pages, 4 figures, 1 table. Submitted to Physical Review D Rapid Communications. Postscript file of paper is also available at http://www-cdf.fnal.gov/physics/pub97/cdf3276_dijet_search_prd_rc.p

SSC collider dipole magnet end mechanical design

This paper describes the mechanical design of the ends of Superconducting Super Collider dipole magnets to be constructed and tested at Fermilab. Coil end clamps, end yoke configuration, and end plate design are discussed. Loading of the end plate by axial Lorentz forces is discussed. Relevant data from 40 mm and 50 mm aperture model dipole magnets built and tested at Fermilab are presented. In particular, the apparent influence of end clamp design on the quench behavior of model SSC dipoles is described. 8 refs., 3 figs

Initial results from 50mm short SSC dipoles at Fermilab

Several short model SSC 50 mm bore dipoles are being built and tested at Fermilab. Mechanical design of these magnets has been determined from experience involved in the construction and testing of 40 mm dipoles. Construction experience includes coil winding, curing and measuring, coil end part design and fabrication, ground insulation, instrumentation, collaring and yoke assembly. Fabrication techniques are explained and construction problems are discussed. Similarities and differences from the 40 mm dipole tooling and management components are outlined. Test results from the first models are presented. 19 refs., 12 figs

Search for New Particles Decaying to Dijets in p-pbar Collisions at sqrt(s)=1.8 TeV

We have used 19 pb**-1 of data collected with the Collider Detector at Fermilab to search for new particles decaying to dijets. We exclude at 95% confidence level models containing the following new particles: axigluons with mass between 200 and 870 GeV, excited quarks with mass between 80 and 570 GeV, and color octet technirhos with mass between 320 and 480 GeV.Comment: Submitted to Physical Review Letters in December 199

Ratios of bottom meson branching fractions involving J/psi mesons and determination of b quark fragmentation fractions

We report a measurement of the ratios of the decay rates of the B^+, B^0 and B^0_s mesons into exclusive final states containing a J/psi meson. The final states were selected from 19.6 pb^{-1} of p-pbar collisions recorded by the Collider Detector at Fermilab. These data are interpreted to determine the bquark fragmentation fractions f_u, f_d and f_s. We also determine the branching fractions for the decay modes B^+ --> J/psi K^+, B^+ --> J/psi K^*(892)^+, B^0 --> J/psi K^0, B^0 --> J/psi K^*(892)^0 and B_s^0 --> J/psi phi(1020). We discuss the implications of these measurements to B meson decay models.Comment: 40 pages with 5 figures. Submitted to Phys. Rev. D. PostScript also available at http://www-cdf.fnal.gov/physics/pub96/cdf3609_bfrag_br_prd.p

Measurement of σ⋅B(W→eν)\sigma \cdot B (W \to e \nu) and σ⋅B(Z0→e+e−)\sigma \cdot B(Z^0 \to e^+e^-) in ppˉp {\bar p} collisions at s=1.8\sqrt{s}=1.8 TeV

We present a measurement of $\sigma \cdot B(W \to e \nu)$ and $\sigma \cdot B(Z^0 \to e^+e^-)$ in proton - antiproton collisions at $\sqrt{s} =1.8$ TeV using a significantly improved understanding of the integrated luminosity. The data represent an integrated luminosity of 19.7 pb$^{-1}$ from the 1992-1993 run with the Collider Detector at Fermilab (CDF). We find $\sigma \cdot B(W \to e \nu) = 2.49 \pm 0.12$~nb and $\sigma \cdot B(Z^0 \to e^+e^-) = 0.231 \pm 0.012$~nb.Comment: Uses Latex, Article 12 point, figure appended as uuencoded file The full PostScript available via WWW at http://www-cdf.fnal.gov/physics/pub95/cdf3312_sigma_1a_prl_v3.p