Bulletin of the American Physical Society
APS April Meeting 2011
Volume 56, Number 4
Saturday–Tuesday, April 30–May 3 2011; Anaheim, California
Session Q9: Physics of the Top Quark II |
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Sponsoring Units: DPF Chair: David Shih, Rutgers University Room: Grand G |
Monday, May 2, 2011 10:45AM - 10:57AM |
Q9.00001: Measurement of the Top Quark Mass using Events with a MET+Jets Signature Jian Tang A top quark mass measurement using the so-called ``MET+Jets'' events are presented. The events used are triggered by the MULTI{\_}JET trigger and have significant missing Et. After a set of clean-up cuts, the events that pass the selection mainly have the signature of ``lepton + jets'' channel of ttbar events but either have one lepton excaping undetected or have a lepton that doesn't pass the usual cuts of tight lepton or loose muon, which makes these events ``orthogonal'' to the usual high-Pt-lepton triggered events in the ttbar ``lepton + jets'' channel and its ``all-hadronic'' channel. A template method is used for this analysis which compares the data events with a set of Monte Carlo simulated samples using 3-dimentional kernel density estimation (KDE) technique, and a maximum-log-likelihood method is used for fitting the final top quark mass. This is the first time these events are used in top quark mass measurement of CDF Run II and we see comparable number of events of this final state compared to the usual ``lepton + jets'' channel. This analysis will give complementary and independant result to the CDF top quark mass measurements. [Preview Abstract] |
Monday, May 2, 2011 10:57AM - 11:09AM |
Q9.00002: A Matrix Element Analysis measurement of the Top Quark Mass in the hadronic tau + jets channel with an in situ Jet Energy Scale measurement from W to jj Daryl Hare We use a 2D unbinned likelihood fit, as used in previous precision top quark mass measurements, with events from lepton + jet top quark decays where the lepton has been identified as a hadronically decaying tau. We use ppbar collisions at 1.96 TeV at CDF. Events require a single lepton identified as a hadronic tau, missing Et, and 4 jets of which at least one must be tagged as a b jet. The likelihood fit is based on per-event probabilities calculated from leading-order signal (ttbar) and background (W+jets) matrix elements. Our goal is to directly identify this final state for the first time as well as provide a top quark mass measurement in this decay channel. [Preview Abstract] |
Monday, May 2, 2011 11:09AM - 11:21AM |
Q9.00003: Background model for measurement of top mass in fully hadronic channel at D0 Ayesh Jayasinghe We present the status and describe the measurement of the top quark mass using the all hadronic final state from data collected with the D0 detector at the Fermilab Tevatron. The data sample selected for this analysis consists of six of more hadronic jets with two jets required to have a secondary vertex, which is indicative of a $b$ quark jet. A multivariate discriminant is used to separate signal from background. The background is modeled using a sample of four and five jet events to which is added the appropriate number of additional jets with the jets taken from six jet events. The tuning of this model and its comparison to data will also be discussed. [Preview Abstract] |
Monday, May 2, 2011 11:21AM - 11:33AM |
Q9.00004: Top Antitop Mass difference Liang Li We update the previous D0 measurement of the mass difference between top and antitop quarks in lepton+jets final states produced in $p\bar{p}$ collisions at $\sqrt{s}$ = 1.96 TeV. The $t\bar{t}$ purity of the lepton+jets sample is enhanced by applying a neural-network-based $b$-tagging technique. Using the Matrix Element approach developed at D0, the combination of the e+jets and mu+jets channels in data corresponding to 3.6 fb$^{-1}$, is used to extract a $t\bar{t}$ mass difference. [Preview Abstract] |
Monday, May 2, 2011 11:33AM - 11:45AM |
Q9.00005: CP-odd violating anomalous top-quark couplings at D0 Seewook Lee We conduct the first study of the T-odd correlations in $t\bar{t}$ events produced in $p\bar{p}$ collision at the Fermilab Tevatron collider that can be used to search for CP violation. We select events which have lepton+jets final states to identify $t\bar{t}$ events and measure asymmetries of several physics observables. Based on the results, we examine possible top quark anomalous couplings at the production vertex and estimate limits on the chromo-electric dipole moment of the top quark. [Preview Abstract] |
Monday, May 2, 2011 11:45AM - 11:57AM |
Q9.00006: Measurement of the top quark electric charge Jeong Ku Lim In the Standard Model, the electric charge of the top quark is predicted to be 2/3 of the electron charge. Experimentally, the more exotic possibility of 4e/3 is not excluded yet. We present the method to measure the top quark charge, which is based on $b$ and $\bar{b}$ jet charge templates obtained by applying a jet charge algorithm to $b$-tagged jets. In this talk, we present the measurement of the top quark charge using $t\bar{t}$ vents in the lepton+4jets final state with two identified $b$-jets, using 5.4 fb$^{-1}$ of data recorded with the D0 detector at the Fermilab Tevatron collider. [Preview Abstract] |
Monday, May 2, 2011 11:57AM - 12:09PM |
Q9.00007: Study of Top Quark Decays into Tau Leptons and Impact on the Higgs Search of the CDF Experiment Matteo Corbo The study of top quark pair production decaying in tau leptons represent a tool for testing the Standard Model and a probe to explore the existence of new physics beyond the Standard Model. We intend to the amplitude of the process with one tau decaying in hadrons and one tau in lighter leptons. The integrated luminosity of CDF RunII, soon 10 fb$^{-1}$, and new analysis tools, will allow to explore the possible contribution from the t-$>$H+b, where H+ is the charged Higgs boson predicted by several supersymmetric of the Standard Model. The current status of the analysis will be presented, which is designed to the event selection efficiency obtained by previous studies. This is possible through the use of data by triggers with low energy and momentum thresholds, in combination to the latest techniques on tauidentification. [Preview Abstract] |
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