Measurement of correlated μ−overlineb\mu - {overline b} jet cross sections in ppˉp {\bar p} collisions at s=1.8\sqrt{s}=1.8 TeV

We report on measurements of differential $\mu - {\bar b}$ cross sections, where the muon is from a semi-leptonic $b$ decay and the ${\bar b}$ is identified using precision track reconstruction in jets. The semi-differential correlated cross sections, d$\sigma$/d\Et^{{\bar b}}, d$\sigma$/d\pt^{{\bar b}}, and d$\sigma$/d$\delta\phi(\mu - {\bar b})$ for \pt^{\mu}>~9 GeV/c, $|\eta^{\mu}|$~10 GeV, $|\eta^{{\bar b}}|<$~1.5, are presented and compared to next-to-leading order QCD calculations.Comment: Uses Latex, Article 12 point, figures appended as uuencoded file The full PostScript available via WWW at http://www-cdf.fnal.gov/physics/pub95/cdf3164_mu_bbar_prd_final.p

A Comparison of Data-Access Platforms for the Computing of Large Hadron Collider Experiments

Performance, reliability and scalability in data-access are key issues in the context of the computing Grid and High Energy Physics data processing and analysis applications, in particular considering the large data size and I/O load that a Large Hadron Collider data centre has to support. In this paper we present the technical details and the results of a large scale validation and performance measurement employing different data-access platforms\u2014namely CASTOR, dCache, GPFS and Scalla/Xrootd. The tests have been performed at the CNAF Tier-1, the central computing facility of the Italian National Institute for Nuclear Research (INFN). Our storage back-end was based on Fibre Channel disk-servers organized in a Storage Area Network, being the disk-servers connected to the computing farm via Gigabit LAN. We used 24 disk-servers, 260 TB of raw-disk space and 280 worker nodes as computing clients, able to run concurrently up to about 1100 jobs. The aim of the test was to perform sequential and random read/write accesses to the data, as well as more realistic access patterns, in order to evaluate efficiency, availability, robustness and performance of the various data-access solutions

MEASUREMENT OF THE B+ AND B0 MESON LIFETIMES

The lifetimes of the B+ and B0 mesons have been measured using fully reconstructed decays. In a sample of approximately 49 600 J/psi --> mu+mu- decays recorded with the Collider Detector at Fermilab, 148 +/- 16 B+ and 121 +/- 16 B0 mesons have been reconstructed using the silicon vertex detector. Unbinned likelihood fits to the proper lifetime distributions of these B mesons give tau+ = 1.61 +/- 0.16 (stat) +/- 0.05 (syst) ps, tau0 = 1.57 +/- 0.18 (stat) +/- 0.08 (syst) ps, and tau+/tau0 = 1.02 +/- 0.16 (stat) +/- 0.05 (syst)

SEARCH FOR NEW GAUGE BOSONS DECAYING INTO DIELECTRONS IN (P)OVER-BAR-P COLLISIONS AT ROOT-S=1.8 TEV

We have searched for heavy neutral gauge bosons (Z') in p̄p collisions at s=1.8 TeV. The data were obtained using the CDF detector during the 1992-1993 run corresponding to an integrated luminosity of 19.7±0.7 pb-1. We present a 95% confidence level upper limit on the production cross section times the branching ratio of Z' decaying into dielectrons as a function of Z' mass. Assuming standard model coupling strengths, we exclude a Z' with a mass less than 505 GeV/c2. We also present lower mass limits for Z' bosons from E6 models and the alternative left-right model. © 1995 The American Physical Society