Bulletin of the American Physical Society
APS April Meeting 2013
Volume 58, Number 4
Saturday–Tuesday, April 13–16, 2013; Denver, Colorado
Session L11: Top Quark at LHC and Tevatron |
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Sponsoring Units: DPF Chair: Howard Haber, University of California, Santa Cruz Room: Governor's Square 17 |
Sunday, April 14, 2013 3:30PM - 3:42PM |
L11.00001: Measurement of the $t\bar{t}$ cross section in the $\tau$ plus jets final state using the ATLAS detector William Edson, Teeba Rashid, Anirvan Sircar We present a measurement of the top quark pair ($t\bar{t}$) production cross section in the $\tau$ plus jets final state at a center-of-mass energy 7 TeV. The analysis is based on proton-proton collisions collected with the ATLAS detector at the CERN LHC. A multivariate analysis technique is used to identify the $\tau$ lepton. Our results are in good agreement with standard model predictions and other top pair cross section measurements. [Preview Abstract] |
Sunday, April 14, 2013 3:42PM - 3:54PM |
L11.00002: Top mass measurement in the all-jet channel with a template method Ayesh Jayasinghe We describe the measurement of the top quark mass applying a template method in the all hadronic jets final state using the full data set collected with the D0 detector at the Fermilab Tevatron collider. The data sample selected for this analysis consists of six hadronic jets with two jets required to have a secondary vertex, which is indicative of a $b$ quark jet. The method employs templates that are generated by selecting the reconstructed top quark mass and $W$ boson mass from a kinematic fitter applied to Monte Carlo generated signal and data-derived background. The templates are then compared to data to extract the top quark mass and jet energy scale correction. The current status of the analysis including the calibration procedure will be discussed. [Preview Abstract] |
Sunday, April 14, 2013 3:54PM - 4:06PM |
L11.00003: Motivation and event selection for the top quark pair production differential cross-section with ATLAS Clare Bernard This talk presents the Monte Carlo and event selections used in the measurement of the top quark pair production differential cross-section in the lepton (electron or muon) + jets channel with a discussion of the motivation. The analysis uses data collected using the ATLAS detector at $\sqrt{s}$ = 7 TeV in 2011. The differential cross-section is measured as a function of the top quark transverse momentum and as a function of the transverse momentum, mass, and rapidity of the $t\bar{t}$ system. Measured distributions are corrected for detector acceptance and resolution and the resulting spectra have good agreement with theoretical predictions. [Preview Abstract] |
Sunday, April 14, 2013 4:06PM - 4:18PM |
L11.00004: Unfolding techniques in the ATLAS top differential cross-section measurement Taylor Childers The Large Hadron Collider at CERN produces top anti-top quark pairs with a cross section that is more than ten times that of the Tevatron. This provides an unparalleled ability to study the top quark which is the most massive of the known fundamental constituents of matter. The latest ATLAS measurements of the differential top quark pair production cross-sections in the lepton plus jets channel have been made with data collected during the 2011 data taking period using proton-proton collisions at a center-of-mass energy of 7TeV. A discussion of the possible unfolding techniques which correct for detector and resolution affects in the data will be presented in order to motivate the decision to use the Singular Value Decomposition. [Preview Abstract] |
Sunday, April 14, 2013 4:18PM - 4:30PM |
L11.00005: A measurement of top quark pair differential cross-section $d\sigma/dm_{t\bar t}$ in the dilepton channel Ki Lie, Steven Errede, Irene Vichou This analysis presents a study of the measurement of the differential cross section as a function of invariant mass of the top quark pairs using 7TeV 2011 data recorded by the ATLAS detector at the Large Hadron Collider. Events of top-antitop pairs are selected in the di-lepton channel. The reconstructed differential distribution is subtracted with estimated backgrounds and is unfolded to correct for detector response and acceptance using the SVD algorithm. Tests on unfolding with MC simulated data are performed. Effects of the main sources of systematic uncertainties on the differential distribution are estimated. [Preview Abstract] |
Sunday, April 14, 2013 4:30PM - 4:42PM |
L11.00006: Measurement of the single top associated production cross section with ATLAS Peng Ge, Reinhard Schwienhorst, Huaqiao Zhang The production cross section of a W boson associated with a single top-quark is measured with the ATLAS detector in pp collisions at the LHC. Events containing at least one central high pt jet and two oppositely-charged leptons are selected. To separate the Wt signal from the large backgrounds, a boosted decision trees method is employed that combines several discriminant variables into one classifier. A template fit to the classifier output distribution is used to measure the signal cross section. The CKM matrix element Vtb is also determined from this measurement. [Preview Abstract] |
Sunday, April 14, 2013 4:42PM - 4:54PM |
L11.00007: Search for associated production of a single top quark with a W boson Daniel Noonan A search for the production of a single top quark in association with a W boson in pp collisions using data collected with the CMS experiment at the LHC is presented. The analysis looks for the tW production decaying into a dilepton final state using a multivariate analysis to separate the signal from the $t\bar{t}$ background. Evidence is presented based on data collected at a center of mass energy of $\sqrt{s}$ = 7 TeV during 2011, and at $\sqrt{s}$ = 8 TeV during 2012. [Preview Abstract] |
Sunday, April 14, 2013 4:54PM - 5:06PM |
L11.00008: America's Next Top Model: Probing the $tWb$ Vertex with Polarized Top Quarks Kevin Sapp Single top quark production is a subject of much detailed study in the higher-statistics sample collected by the ATLAS experiment. It is also the ideal candidate for a standard-model process to provide insight into beyond-standard-model physics; the large top mass and the resulting polarized weak production make deviations from the expected angular distribution of the decay a clear sign of new contributions to the effective $tWb$ vertex. We present a procedure to constrain the amplitudes and phases in this transition using a two-dimensional likelihood function incorporating efficiency, resolution, and backgrounds analytically, and extract detailed coupling information which will indicate where new physics coupling to the top quark can exist. [Preview Abstract] |
Sunday, April 14, 2013 5:06PM - 5:18PM |
L11.00009: Search for Highly Collimated Top Quarks with the ATLAS Detector Daniel Pluth A search for the production of top quarks with high transverse momentum (pt \textgreater\ 750 GeV) in pp collisions has been performed at ATLAS. Top quarks decaying to all hadronic final states are reconstructed in single collimated jets. A complementary cone method is used to mediate the effects of multiple pp collisions during high luminosity data taking. The measured cross-section is compared to Standard Model predictions. [Preview Abstract] |
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