Bulletin of the American Physical Society
2007 APS April Meeting
Volume 52, Number 3
Saturday–Tuesday, April 14–17, 2007; Jacksonville, Florida
Session J14: Top I |
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Sponsoring Units: DPF Chair: Dan Amidei, University of Michigan Room: Hyatt Regency Jacksonville Riverfront City Terrace 10 |
Sunday, April 15, 2007 10:30AM - 10:42AM |
J14.00001: Measurement of the $W$ boson helicity in top quark decay at D0 Bertrand Martin We report on a measurement of the fraction of right-handed $W$ bosons in top quark decay. In the standard model, this fraction is too small to measure with the current data sample, so a non-zero value would be a clear sign of new physics. The measurement is based upon the angle between the charged lepton and top quark directions in the $W$ boson rest frame. [Preview Abstract] |
Sunday, April 15, 2007 10:42AM - 10:54AM |
J14.00002: ABSTRACT WITHDRAWN |
Sunday, April 15, 2007 10:54AM - 11:06AM |
J14.00003: Search for a Charged Higgs in Top Decays at CDF Geum-bong Yu We present a search for an anomalous boson in top decays using pair produced top events from $p\bar{p}$ collisions at CDF II. Our search focuses on a boson which decays into two jets, like hadronic W decays in the lepton+jets channel. With well identified lepton and b jets, we look for a new mass bump in the di-jet mass distribution. For the most favored candidate, a charged Higgs boson at low tan (beta) within MSSM, we present the sensitivity of finding a charged Higgs in the region from 100 to 160 GeV. [Preview Abstract] |
Sunday, April 15, 2007 11:06AM - 11:18AM |
J14.00004: Measurement of the top quark mass at D0 using the matrix weighting method on dilepton events Daniel Boline, Ulrich Heintz We present a measurement of the top quark mass in the dilepton channel based on approximately 1~fb$^{-1}$ of data collected by the D0 experiment during Run II of the Fermilab Tevatron collider. The kinematics of these events are not sufficiently constrained by the observed final state to reconstruct the top quark mass. We therefore compute a likelihood for the observed events to occur for a range of assumed top quark masses. For each event we choose the hypothesized top quark mass at which this likelihood is maximized as the estimator for the top quark mass. We compare the distribution of this estimator for all events to Monte Carlo predictions for different input top quark masses in a maximum likelihood fit to extract the top quark mass. [Preview Abstract] |
Sunday, April 15, 2007 11:18AM - 11:30AM |
J14.00005: Search for Resonant $t\bar{t}$ Pair Production in the Lepton+Jets Channel at CDF Junji Naganoma We present a search for the $t\bar{t}$ resonance which interferes with the Standard Model process. The data are collected in CDF Run2 experiment from $p\bar{p}$ collisions at Tevatron with the integrated luminosity of 1.2 fb$^{-1}$. We select lepton+jets events requiring at least one jet to be identified as a b-jet. We then reconstruct the $t\bar{t}$ invariant mass by the dynamical likelihood method (DLM) to increase the sensitivity for discovery. We search for the deviations from the Standard Model prediction in the $t\bar{t}$ invariant mass spectrum. [Preview Abstract] |
Sunday, April 15, 2007 11:30AM - 11:42AM |
J14.00006: First Measurement of $\sigma(gg\rightarrow t\bar{t})/\sigma(p\bar{p}\rightarrow t\bar{t})$ in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV Shabnaz Pashapour According to the standard model, $t\bar{t}$ can be produced through gluon-gluon fusion or quark-antiquark annihilation. We will present the first measurement of $\sigma(gg\rightarrow t\bar{t})/\sigma(p\bar{p}\rightarrow t\bar{t})$. This analysis uses about 1 fb$^{-1}$ of data collected by Collider Detector at Fermilab (CDF) at $\sqrt{s}=1.96$ TeV to find $t\bar{t}$ candidates in lepton+jets channel. The measurement provides a test of the QCD predictions for this pair-production mechanism, and a technique to test for unexpected sources of top quark production. We take advantage of the correlation between the average low $P_{T}$ track multiplicity and the average number of gluons participating in the high-energy interaction. Using W boson and dijet calibration samples, we define largely no-gluon and gluon-rich samples, respectively, and use the observed track multiplicities to measure the fraction of $t\bar{t}$ events that are produced in gluon-rich interactions. [Preview Abstract] |
Sunday, April 15, 2007 11:42AM - 11:54AM |
J14.00007: Measurement of the charge asymmetry in $t\bar{t}$ production in proton-antiproton collision at D0 Amnon Harel We report on the measurement of forward-backward asymmetry in $t\bar{t}$ production in proton-antiproton collisions. If the component of the top quark momentum along the proton direction is larger than that of antitop the asymmetry is defined as positive and negative otherwise. Top and and antitop momenta are reconstructed in lepton+jets sample using b-tagging information and kinematic constraints. [Preview Abstract] |
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