Bulletin of the American Physical Society
2005 APS April Meeting
Saturday–Tuesday, April 16–19, 2005; Tampa, FL
Session M7: Top Quark Physics II |
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Sponsoring Units: DPF Chair: David Rainwater, Rochester University Room: Marriott Tampa Waterside Room 1 |
Sunday, April 17, 2005 3:15PM - 3:27PM |
M7.00001: Measurement of the Top Quark Mass in the Lepton+Jets Channel at D{\O} Philipp Schieferdecker The top quark mass is one of the fundamental parameters of the Standard Model. At a hadron collider, top quarks are dominantly produced in pairs ($t\bar{t}$), each of them decaying to a $W$~boson and a $b$~quark. We report on the measurement of the mass of the top quark in the lepton+jets final state, using data collected by the D\O\ experiment during Run II of the Fermilab Tevatron collider. The top quark mass is extracted by making use of an event-by-event likelihood built from the matrix elements for signal and background and the detector resolution for the reconstructed decay products, thus making an extensive use of the available statistical information. This method was first applied to the Run I dataset to measure the top quark mass at D\O\ and led to a substantially reduced statistical uncertainty with respect to previous methods. [Preview Abstract] |
Sunday, April 17, 2005 3:27PM - 3:39PM |
M7.00002: Measurement of the Top Quark Mass in the Lepton+Jets Channel at D{\O} Robert Harrington The top quark mass is one of the fundamental parameters of the Standard Model. At a hadron collider, top quarks are dominantly produced in pairs ($t\bar{t}$), each of them decaying to a $W$~boson and a $b$~quark. We report on the measurement of the mass of the top quark in the lepton+jets final state, using data collected by the D\O\ experiment during Run II of the Fermilab Tevatron collider. The top quark mass is extracted by making use of an event-by-event likelihood built from the matrix elements for signal and background and the detector resolution for the reconstructed decay products, thus making an extensive use of the available statistical information. This method was first applied to the Run I dataset to measure the top quark mass at D\O\ and led to a substantially reduced statistical uncertainty with respect to previous methods. The method is further enhanced through secondary vertex tagging, which allows selection of events more likely to have contained $b$-quarks due to the presence of displaced vertices. This technique greatly enhances the purity of the data sample, allowing a potentially more precise measurement of the top quark mass. [Preview Abstract] |
Sunday, April 17, 2005 3:39PM - 3:51PM |
M7.00003: A Method for the Detemination of the Top Quark Mass in the Dilepton+Jets Channel at D{\O} Petr Homola We present a method for the determination of the mass of the top quark in the dilepton+jets final state based on full reconstruction of the $t\bar{t}$ system and weighting of the obtained solutions according to their consistency with the expected transverse momenta of the top quarks and neutrinos. This method has been succesfully applied to Monte Carlo simulations of data from the ATLAS experiment. A discussion on the expected performance of this method when applied to dilepton+jets samples selected by the D\O\ experiment in Run II will also be given. [Preview Abstract] |
Sunday, April 17, 2005 3:51PM - 4:03PM |
M7.00004: Measurement of the Top Quark Mass in D\O\ using the Ideogram Method Martijn Mulders The top quark mass is one of the fundamental parameters of the Standard Model. At a hadron collider, top quarks are dominantly produced in pairs ($t\bar{t}$), each of them decaying to a $W$~boson and a $b$~quark. We report on the measurement of the mass of the top quark in the lepton+jets final state, using data collected by the D\O\ experiment during Run II of the Fermilab Tevatron collider. The top quark mass is determined by using the so-called ``Ideogram Method,'' based on constrained kinematic fitting, but designed to make optimal use of the available information: it build a per-event likelihood taking into account all possible jet permutations, the possibility that the event was background, and the estimated error on the fitted mass for each jet permutation. Information from a $b$-tagging algorithm is also used to further improve the separation between signal and backgrounds. A discussion will also be given on recent progress in the understanding of systematic uncertainties in the top quark measurement. [Preview Abstract] |
Sunday, April 17, 2005 4:03PM - 4:15PM |
M7.00005: Measurement of the Top Quark Mass in the Electron+Muon+Jets Decay Channel at D{\O} Jeff Temple The top quark mass is one of the fundamental parameters of the Standard Model. We present a preliminary measurement of the top quark mass in the electron+muon+jets decay channel of $t\bar{t}$ events, using data collected by the D\O\ experiment during Run II of the Fermilab Tevatron collider. The method used for the top quark mass determination, called the ``neutrino weighting scheme'', makes use of the sensitivity of the neutrino rapidity distribution to the top quark mass. Systematic errors associated with this measurement are also discussed. [Preview Abstract] |
Sunday, April 17, 2005 4:15PM - 4:27PM |
M7.00006: Measurement of Top Branching Ratios at CDF Dmitri Smirnov According to the standard model, the top quark decays to a $W$ boson and a $b$ quark virtually 100\% of the time, and measurements of $t\bar{t}$ production rates depend strongly on that assumption. We test this hypothesis with a measurement of $BR(t \to Wb)/BR(t \to Wq)$, using a combination of event kinematics and b-tagging. We show that the method is independent of the top cross section. We make these comparisons in $t\bar{t}$ samples collected from 340~pb$^{-1}$ of $p\bar{p}$ collision data recorded with the CDF detector at the Tevatron. [Preview Abstract] |
Sunday, April 17, 2005 4:27PM - 4:51PM |
M7.00007: Top Physics in ATLAS Matt Dobbs The LHC can be considered as a top-factory, with about 10 million $t\overline{t}$ events produced in one year of running at low luminosity. This large data set will alllow very precise measurements of the properties of the top quark, which may also reveal New Physics. The mass of the top quark will be measured with a precision of about 1 GeV. The top quark Yukawa coupling can be determined with a precision of better than 10% for a Higgs mass of about 100 GeV. $t\overline{t}$ spin correlations can be observed and used to study anomalous couplings or CP violation. Heavy resonances decaying to $t\overline{t}$ pairs could be detected with masses up to 3 TeV. Rare decays of the top quark can be probed for branching ratios as small as $10^-5$. In addition, the detailed study of three different mechanisms of electroweak single top production will yield a wealth of information, including precision measurements of $V_{tb}$ and of the W and top polarisations, and searches for anomalous couplings. Besides all these interesting possibilities, top events will provide an exceptional tool for the first commissioning studies of the ATLAS detector. [Preview Abstract] |
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