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

Observation of a ppb mass threshoud enhancement in \psi^\prime\to\pi^+\pi^-J/\psi(J/\psi\to\gamma p\bar{p}) decay

The decay channel $\psi^\prime\to\pi^+\pi^-J/\psi(J/\psi\to\gamma p\bar{p})$ is studied using a sample of $1.06\times 10^8$ $\psi^\prime$ events collected by the BESIII experiment at BEPCII. A strong enhancement at threshold is observed in the $p\bar{p}$ invariant mass spectrum. The enhancement can be fit with an $S$-wave Breit-Wigner resonance function with a resulting peak mass of $M=1861^{+6}_{-13} {\rm (stat)}^{+7}_{-26} {\rm (syst)} {\rm MeV/}c^2$ and a narrow width that is $\Gamma<38 {\rm MeV/}c^2$ at the 90% confidence level. These results are consistent with published BESII results. These mass and width values do not match with those of any known meson resonance.Comment: 5 pages, 3 figures, submitted to Chinese Physics

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

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

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

Higher-order multipole amplitude measurement in ψ ′→γχ c2

Using 106×106 ψ ′ events collected with the BESIII detector at the BEPCII storage ring, the higher-order multipole amplitudes in the radiative transition ψ ′→γχ c2→γπ +π -/γK +K - are measured. A fit to the χ c2 production and decay angular distributions yields M2=0.046±0. 010±0.013 and E3=0.015±0.008±0.018, where the first errors are statistical and the second systematic. Here M2 denotes the normalized magnetic quadrupole amplitude and E3 the normalized electric octupole amplitude. This measurement shows evidence for the existence of the M2 signal with 4.4σ statistical significance and is consistent with the charm quark having no anomalous magnetic moment. © 2011 American Physical Society.published_or_final_versio

Branching fraction measurements of χc0 and χc2 to π0π0 and ηη

Using a sample of 1.06×108 ψ ′ decays collected by the BESIII detector, χc0 and χc2 decays into π0π0 and ηη are studied. The branching fraction results are Br(χc0→π 0π0)=(3.23±0.03±0.23±0.14)×10 -3, Br(χc2→π0π0)=(8.8±0.2±0.6±0.4)×10 -4, Br(χc0→ηη)=(3.44±0.10±0. 24±0.2)×10 -3, and Br(χc2→ηη)=(6. 5±0.4±0.5±0.3)×10 -4, where the uncertainties are statistical, systematic due to this measurement, and systematic due to the branching fractions of ψ ′→ γχcJ. The results provide information on the decay mechanism of χc states into pseudoscalars. © 2010 The American Physical Society.published_or_final_versio

First observation of the decays χcJ→π0π0π0π0

We present a study of the P-wave spin-triplet charmonium χ cJ decays (J=0, 1, 2) into π0π0π0π0. The analysis is based on 106×106 ψ⊃′ decays recorded with the BESIII detector at the BEPCII electron positron collider. The decay into the π0π0π0π0 hadronic final state is observed for the first time. We measure the branching fractions B(χ c0→π0π0π0π0)=(3.34±0. 06±0.44)×10⊃-3, B(χ c1→π0π0π0π0) =(0.57±0.03±0.08)×10⊃-3, and B(χ c2→π0π0π0π0)=(1.21±0.05±0.16) ×10⊃-3, where the uncertainties are statistical and systematical, respectively. © 2011 American Physical Society.published_or_final_versio