Kt-jets and jet structure and fragmentation at the Tevatron

Kt algorithms are now used by both D0 and CDF to study jets. A preliminary study of jet structure for data taken by D0 and CDF during run 1 (92-95) is presented. D0 has measured the jet mass as a function of jet p{sub T}. The CDF measurement of inclusive charged particle momentum distributions is in agreement with the Modified Leading Log Approximation (MLLA)

Overview of kinematic variables in top production

A selection of simple kinematic variables chosen to be sensitive to different aspects of {ital t{anti t}} production in W + {>=} 3 jets events are studied. Monte Carlo comparisons are made between different top generators (Herwig, Pythia, and Isajet) and a QCD background generator (VECBOS). Finally, Monte Carlo predictions with the {ital t{anti t}} fraction constrained by the SVX {ital b}-tagging rate and measured top mass are compared with 110 pb{sup -1} of CDF data. We conclude that the CDF data is consistent with standard predictions using the studied generators

Atomic mass dependence of \Xi^- and \overline{\Xi}^+ production in central 250 GeV \pi^- nucleon interactions

We present the first measurement of the atomic mass dependence of central \Xi^- and \overline{\Xi}^+ production. It is measured using a sample of 22,459 \Xi^-'s and \overline{\Xi}^+'s produced in collisions between a 250 GeV \pi^- beam and targets of beryllium, aluminum, copper, and tungsten. The relative cross sections are fit to the two parameter function \sigma_0 A^\alpha, where A is the atomic mass. We measure \alpha = 0.924+-0.020+-0.025, for Feynman-x in the range -0.09 < x_F < 0.15.Comment: 10 pages, revtex, 2 figures, submitted to Phys. Rev.

Nuclear suppression of dileptons at forward rapidities

Data from E772 and E866 experiments on the Drell-Yan process exhibit a significant nuclear suppression at large Feynman xF. We show that a corresponding kinematic region does not allow to interpret this as a manifestation of coherence or a Color Glass Condensate. We demonstrate, however, that this suppression can be treated alternatively as an effective energy loss proportional to initial energy. To eliminate suppression coming from the coherence, we perform predictions for nuclear effects also at large dilepton masses. Our calculations are in a good agreement with available data. Since the kinematic limit can be also approached in transverse momenta pT, we present in the RHIC energy range corresponding predictions for expected large-pT suppression as well. Since a new experiment E906 planned at FNAL will provide us with more precise data soon, we present also predictions for expected large-xF nuclear suppression in this kinematic region.Comment: 6 pages, 4 figures. Talk given at the International Nuclear Physics Conference (INPC-2010), Vancouver, Canada July 4 - 9, 201

Comparison of the total cross sections measurements of CDF and E811

The total cross section at {radical}s = 1.8 TeV has been measured by three groups (CDF, E710, and E811). We think that CDF should quote results based only on our own measurement. We also indicate how to compare cross sections measured by both CDF and D0

Evidence for t\bar{t}\gamma Production and Measurement of \sigma_t\bar{t}\gamma / \sigma_t\bar{t}

Using data corresponding to 6.0/fb of ppbar collisions at sqrt(s) = 1.96 TeV collected by the CDF II detector, we present a cross section measurement of top-quark pair production with an additional radiated photon. The events are selected by looking for a lepton, a photon, significant transverse momentum imbalance, large total transverse energy, and three or more jets, with at least one identified as containing a b quark. The ttbar+photon sample requires the photon to have 10 GeV or more of transverse energy, and to be in the central region. Using an event selection optimized for the ttbar+photon candidate sample we measure the production cross section of, and the ratio of cross sections of the two samples. Control samples in the dilepton+photon and lepton+photon+\met, channels are constructed to aid in decay product identification and background measurements. We observe 30 ttbar+photon candidate events compared to the standard model expectation of 26.9 +/- 3.4 events. We measure the ttbar+photon cross section to be 0.18+0.08 pb, and the ratio of the cross section of ttbar+photon to ttbar to be 0.024 +/- 0.009. Assuming no ttbar+photon production, we observe a probability of 0.0015 of the background events alone producing 30 events or more, corresponding to 3.0 standard deviations.Comment: 9 pages, 3 figure

Precision Top-Quark Mass Measurements at CDF

We present a precision measurement of the top-quark mass using the full sample of Tevatron $\sqrt{s}=1.96$ TeV proton-antiproton collisions collected by the CDF II detector, corresponding to an integrated luminosity of 8.7 $fb^{-1}$. Using a sample of $t\bar{t}$ candidate events decaying into the lepton+jets channel, we obtain distributions of the top-quark masses and the invariant mass of two jets from the $W$ boson decays from data. We then compare these distributions to templates derived from signal and background samples to extract the top-quark mass and the energy scale of the calorimeter jets with {\it in situ} calibration. The likelihood fit of the templates from signal and background events to the data yields the single most-precise measurement of the top-quark mass, \mtop = 172.85 \pm$0.71 (stat)$\pm$0.85 (syst) GeV/c^{2}.$Comment: submitted to Phys. Rev. Let

Search for Narrow Diphoton Resonances and for gamma-gamma+W/Z Signatures in p\bar p Collisions at sqrt(s)=1.8 TeV

We present results of searches for diphoton resonances produced both inclusively and also in association with a vector boson (W or Z) using 100 pb^{-1} of p\bar p collisions using the CDF detector. We set upper limits on the product of cross section times branching ratio for both p\bar p\to\gamma\gamma + X and p\bar p\to\gamma\gamma + W/Z. Comparing the inclusive production to the expectations from heavy sgoldstinos we derive limits on the supersymmetry-breaking scale sqrt{F} in the TeV range, depending on the sgoldstino mass and the choice of other parameters. Also, using a NLO prediction for the associated production of a Higgs boson with a W or Z boson, we set an upper limit on the branching ratio for H\to\gamma\gamma. Finally, we set a lower limit on the mass of a `bosophilic' Higgs boson (e.g. one which couples only to \gamma, W, and Z$ bosons with standard model couplings) of 82 GeV/c^2 at 95% confidence level.Comment: 30 pages, 11 figure