Bulletin of the American Physical Society
2007 APS April Meeting
Volume 52, Number 3
Saturday–Tuesday, April 14–17, 2007; Jacksonville, Florida
Session K14: Top II |
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Sponsoring Units: DPF Chair: Pushpalatha Bhat, Fermi National Accelerator Laboratory Room: Hyatt Regency Jacksonville Riverfront City Terrace 10 |
Sunday, April 15, 2007 1:15PM - 1:27PM |
K14.00001: Measurement of the top quark mass at D0 using all-hadronic events David Lam We report on the measurement of the top quark mass using $t\bar {t}$ candidates in the all-hadronic decay channel. The $t\bar{t}$ signal was discriminated from background using kinematic information and by requiring two identified $b$ jets. The mass was extracted by comparing templates of $t\bar{t}$ signal and multi-jet background to the selected candidates. [Preview Abstract] |
Sunday, April 15, 2007 1:27PM - 1:39PM |
K14.00002: Top Quark Mass Measurement in the Lepton+Jets Channel at CDF using a Template Method Young-Jang Lee We present a measurement of the top quark mass in top quark pair production events decaying into the lepton+jets channel. The measurement uses proton-antiproton collision data at $\sqrt{s}=1.96$ TeV collected by CDF Run II detector at Fermilab. We reconstruct a top quark mass in each event by using kinematic constraints on the pair of top quarks and the mass of the hadronic decaying W boson to calibrate the energy response of the detector. We determine the top quark mass and an \textit{in situ} measurement of the jet energy scale from a simultaneous likelihood fit to the reconstructed top quark mass and W boson invariant mass distributions in the data to distributions from Monte Carlo simulation. [Preview Abstract] |
Sunday, April 15, 2007 1:39PM - 1:51PM |
K14.00003: Measurement of the top quark mass at D0 using the ideogram method in the lepton+jets channel Pieter Houben We report on the measurement of the top quark mass using $t\bar {t}$ candidates in the lepton+jets final state. For each event, a probability based on the kinematic reconstruction of the event is calculated as a function of the top mass and the overall jet energy scale. The top mass and jet energy scale are extracted by maximizing a likelihood constructed as the product of the single event probabilities. The overall jet energy scale is constraint by the two jets from the hadronic W boson decay. [Preview Abstract] |
Sunday, April 15, 2007 1:51PM - 2:03PM |
K14.00004: Addition of the Trilepton Channel to the Search for Top Flavor Changing Neutral Current (FCNC) Decays at CDF Jennifer Gimmell In the CDF II detector at the Fermilab Tevatron, $t\bar{t}$ pairs are produced in $p\bar{p}$ collisions at 1.96 TeV. We have performed a search for flavor-changing neutral current (FCNC) decays of the top quark: $t\bar{t}\rightarrow Wb Zq$. In this talk, we present the effects of adding a new leptonic decay channel to our analysis. Our current search at CDF II consists of $t\bar{t}$ pairs decaying into a hadronically decaying $W$, a leptonically decaying $Z$, and jets. The additional trilepton channel, the decay of $t\bar{t}$ pairs into a $W$ and $Z$ both decaying leptonically with jets, will increase the sensitivity for our top FCNC search. Using a Feldman-Cousins expected limit technique, we examine the improvement on the limit of our current top FCNC search as a function of the luminosity by adding this channel. [Preview Abstract] |
Sunday, April 15, 2007 2:03PM - 2:15PM |
K14.00005: First Measurement of the Top Quark Charge at CDF II Zeynep Unalan Since top quark's discovery in 1995, there have been several measurements of the top quark's mass and cross section. Due to this quark's special role in electroweak symmetry breaking, other parameters such as its charge and spin should also be measured. We present the first CDF measurement of the top quark's charge using its decay products from a sample of 1.2 fb$^{-1}$ of data collected with the CDFII detector at the Tevatron collider at Fermilab. The standard model predicts the top quark charge to be +2/3 but alternative theories allow a fourth generation exotic quark with a charge of -4/3. We classify events as either top-like or exotic-like depending on the the charge of the b jet and of the associated W boson. We report confidence level limits for the data to exclude the exotic or standard model hypothesis. [Preview Abstract] |
Sunday, April 15, 2007 2:15PM - 2:27PM |
K14.00006: ABSTRACT WITHDRAWN |
Sunday, April 15, 2007 2:27PM - 2:39PM |
K14.00007: Measurement of the top quark charge and branching fractions at D0 Per Hansson We report on a measurement of the ratio $R = B(t\rightarrow Wb)/B(t\rightarrow Wq)$. In the standard model this ratio exceeds 0.998 at the 95\% confidence level. Experimentally, we measure the ratio based on the fraction of candidate events with 0, 1, or 2 b-tagged jets. We also report on a measurement of the charge of the top quark by resolving the kinematic ambiguity between the standard model scenario of a charge 2/3 quark decaying to $W^+b$ and an exotic scenario of a charge $-4/3$ quark decaying to $W^-b$. [Preview Abstract] |
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