Diffractive Dijet Production at sqrt(s)=630 and 1800 GeV at the Fermilab Tevatron

We report a measurement of the diffractive structure function $F_{jj}^D$ of the antiproton obtained from a study of dijet events produced in association with a leading antiproton in $\bar pp$ collisions at $\sqrt s=630$ GeV at the Fermilab Tevatron. The ratio of $F_{jj}^D$ at $\sqrt s=630$ GeV to $F_{jj}^D$ obtained from a similar measurement at $\sqrt s=1800$ GeV is compared with expectations from QCD factorization and with theoretical predictions. We also report a measurement of the $\xi$ ($x$-Pomeron) and $\beta$ ($x$ of parton in Pomeron) dependence of $F_{jj}^D$ at $\sqrt s=1800$ GeV. In the region $0.035<\xi<0.095$, $|t|<1$ GeV$^2$ and $\beta<0.5$, $F_{jj}^D(\beta,\xi)$ is found to be of the form $\beta^{-1.0\pm 0.1} \xi^{-0.9\pm 0.1}$, which obeys $\beta$-$\xi$ factorization.Comment: LaTeX, 9 pages, Submitted to Phys. Rev. Letter

A Study of B0 -> J/psi K(*)0 pi+ pi- Decays with the Collider Detector at Fermilab

We report a study of the decays B0 -> J/psi K(*)0 pi+ pi-, which involve the creation of a u u-bar or d d-bar quark pair in addition to a b-bar -> c-bar(c s-bar) decay. The data sample consists of 110 1/pb of p p-bar collisions at sqrt{s} = 1.8 TeV collected by the CDF detector at the Fermilab Tevatron collider during 1992-1995. We measure the branching ratios to be BR(B0 -> J/psi K*0 pi+ pi-) = (8.0 +- 2.2 +- 1.5) * 10^{-4} and BR(B0 -> J/psi K0 pi+ pi-) = (1.1 +- 0.4 +- 0.2) * 10^{-3}. Contributions to these decays are seen from psi(2S) K(*)0, J/psi K0 rho0, J/psi K*+ pi-, and J/psi K1(1270)

Search for Single-Top-Quark Production in p-pbar Collisions at sqrt(s)=1.8 TeV

We search for standard model single-top-quark production in the W-gluon fusion and W* channels using 106 pb^-1 of data from p-pbar collisions at sqrt(s)=1.8 TeV collected with the Collider Detector at Fermilab. We set an upper limit at 95% C.L. on the combined W-gluon fusion and W* single-top cross section of 14 pb, roughly six times larger than the standard model prediction. Separate 95% C.L. upper limits in the W-gluon fusion and W* channels are also determined and are found to be 13 and 18 pb, respectively.Comment: 6 pages, 2 figures; submitted to Phys. Rev. Let

Measurement of the Ratio of b Quark Production Cross Sections in Antiproton-Proton Collisions at 630 GeV and 1800 GeV

We report a measurement of the ratio of the bottom quark production cross section in antiproton-proton collisions at 630 GeV to 1800 GeV using bottom quarks with transverse momenta greater than 10.75 GeV identified through their semileptonic decays and long lifetimes. The measured ratio sigma(630)/sigma(1800) = 0.171 +/- .024 +/- .012 is in good agreement with next-to-leading order (NLO) quantum chromodynamics (QCD)

Observation of Xi - production in e+e- annihilation at 29 GeV.

Inclusive - production in e+e- annihilation at 29 GeV has been measured with the Mark II detector. From an integrated luminosity of 207 pb-1, we determine a production rate of 0.0170.0040.004 -++ per hadronic event. A search for *0(1530)-+ leads to an upper limit of N(*0)/N(-)&lt;0.35 at a 90% confidence level. © 1987 The American Physical Society

Measurement of γγψ final states in ψ′ decay

The decay mode ψ′→γγψ has been studied with the Mark-II detector at SPEAR. New measurements of branching ratios for decays of the type ψ′→γχ, χ→γψ involving known χ states are presented. The existence of a χ state of mass near 3455 MeV/c2 produced in this decay chain is not confirmed, and the upper limit (90% confidence level) of the product of branching ratios is measured to be 0.13%. A new decay mode, ψ′→π0ψ, which violates isospin conservation is observed with branching ratio (0.15±0.06)%. © 1980 The American Physical Society

Measurement of γγψ final states in ψ′ decay

The decay mode ψ′→γγψ has been studied with the Mark-II detector at SPEAR. New measurements of branching ratios for decays of the type ψ′→γχ, χ→γψ involving known χ states are presented. The existence of a χ state of mass near 3455 MeV/c2 produced in this decay chain is not confirmed, and the upper limit (90% confidence level) of the product of branching ratios is measured to be 0.13%. A new decay mode, ψ′→π0ψ, which violates isospin conservation is observed with branching ratio (0.15±0.06)%. © 1980 The American Physical Society

Observation of the c (2980) Produced in the Radiative Decay of the (3684)

In a study of (3684) radiative decays with the Mark II detector at SPEAR, the decay sequence c (2980) is observed, with the c (2980) decaying into several completely reconstructed hadronic modes. A mass M=29808 MeV/c2 and a width &lt;40 MeV/c2 (90%) confidence level) are obtained, and estimates of some of the decay branching ratios are presented. © 1980 The American Physical Society