Bulletin of the American Physical Society
APS April Meeting 2010
Volume 55, Number 1
Saturday–Tuesday, February 13–16, 2010; Washington, DC
Session K9: Top Quark Physics I |
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Sponsoring Units: DPF Chair: Cecilia Gerber, University of Illinois at Chicago Room: Maryland A |
Sunday, February 14, 2010 3:30PM - 3:42PM |
K9.00001: Measurement of the top pair production cross section in the Lepton+jets channel with D0 RunII data Sehwook Lee We present a measurement of the production cross section of top quark pairs at a center-of-mass energy of 1.96 TeV. This analysis is based on the selection of events with one charged lepton (electron or muon), missing transverse energy, and 3 or more jets. We utilize the e+jets and mu+jets data samples corresponding to integrated luminosity of 5.4/fb collected using the D0 detector. To help distinguish the signal from the background processes, we use a neural network algorithm that uses lifetime information to identify the b-quark jets that are associated with top quark decays. We require at least one b-tagged jet to be identified in this analysis. [Preview Abstract] |
Sunday, February 14, 2010 3:42PM - 3:54PM |
K9.00002: ABSTRACT WITHDRAWN |
Sunday, February 14, 2010 3:54PM - 4:06PM |
K9.00003: Study of measurement of the $t\bar{t}$\ cross section in the electron + jets channel at ATLAS using kinematic information Babak Abi The observation of the top quark will be an important milestone at LHC. We present a study of the prospects for measuring the $t\bar{t}$production cross-section with the ATLAS detector at a center-of-mass energy of 10~TeV with one electron, missing transverse energy, and at least four jets in the final state. The $t\bar{t}$\ signal is discriminated from background processes using kinematic information. Several kinematic variables are combined into a multivariate discriminant to maximize the separation between signal and background. The aim of this method is to make an early measurement of the $t\bar{t}$\ cross section. Once ATLAS has accumulated 50~pb$^{-1}$\ of integrated luminosity, then we expect to measure the $t\bar{t}$cross section to an accuracy of 7\% from statistical uncertainties and 26\% from systematic uncertainties. [Preview Abstract] |
Sunday, February 14, 2010 4:06PM - 4:18PM |
K9.00004: $t\bar{t}$ Cross Section Measurement in Muon + Jets Channel at ATLAS Using Kinematic Information Dilip Jana We present a Monte Carlo study of prospects for measuring the $t\bar{t}$ production cross-section with the ATLAS detector at a center-of-mass energy of 10 TeV using events with one muon, missing transverse energy, and at least four jets in the final state. We employ a multivariate technique which uses the kinematic and topological information of the event to separate $t\bar{t}$ signal from background processes. The suggested method is aimed at early measurement of the $t\bar{t}$ cross section using 50 pb$^{-1}$ of data. Assuming this amount of data, the $t\bar{t}$ cross section can be measured with accuracy of $\Delta\sigma / \sigma = \pm 25\%$ (syst) $\pm 6\% $ (fit+stat). [Preview Abstract] |
Sunday, February 14, 2010 4:18PM - 4:30PM |
K9.00005: Measurement of the forward-backward asymmetry in top quark pair production at the D0 experiment Douglas Orbaker We are presenting an update of the measurement of the forward-backward asymmetry in top quark pair production in proton-antiproton collisions. The measurement is performed on events in the lepton + jets final state selected with a neural net b-tagger and reconstructed with a kinematic fitter. The new measurement will use a data set of 5.4/fb, collected by the D0 experiment at the Fermilab Tevatron collider at a center-of-mass energy of 1.96 TeV. [Preview Abstract] |
Sunday, February 14, 2010 4:30PM - 4:42PM |
K9.00006: Measurement of top pair spin correlation using CDF Run II lepton+jets data David Mietlicki Top quark spin is one of the most interesting, yet not well-measured, quantities in top physics. Standard model top pair production through qq annihilation or gluon fusion produces a characteristic spin correlation which can be modified by exotic production mechanisms such as Z' bosons or KK gluons. According to the standard model, top quarks decay weakly before any hadronization processes take effect. This enables top quark spin information to be transmitted to the top quark decay products. We report on the observation and measurement of the t-tbar spin correlation using lepton+jet events in 4.5/fb of CDF data. [Preview Abstract] |
Sunday, February 14, 2010 4:42PM - 4:54PM |
K9.00007: Measurement of spin correlation in top quark pair production at the D0 experiment Tim Head A measurement of the correlation between the spin of the top and the spin of the anti-top quark produced in proton anti-proton scattering at a center of mass energy of 1.96 TeV is presented. This measurement uses up to 4.2/fb of data collected by the D0 detector at the Tevatron collider. The SM predicts that the top quark decays before it hadronizes, in contrast with the lighter quarks, which are depolarized by QCD interactions long before they decay. The spin of the top quark is therefore reflected by its decay products. We analyze a double differential angular distribution of the charged leptons from top and anti-top decays in final states with two charged leptons, missing transverse energy and at least two jets. The measured strength of the spin correlation is in agreement with the SM prediction. [Preview Abstract] |
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