Bulletin of the American Physical Society
2005 APS April Meeting
Saturday–Tuesday, April 16–19, 2005; Tampa, FL
Session U7: Top Quark Physics III |
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Sponsoring Units: DPF Chair: Peter Wittich, University of Pennsylvania Room: Marriott Tampa Waterside Room 1 |
Monday, April 18, 2005 3:30PM - 3:54PM |
U7.00001: Search for single top quark production at CDF Sarah Budd In proton-antiproton collisions at the Fermilab Tevatron collider, individual top quarks are expected to be produced in association with bottom quarks mainly through the $s$-channel exchange of an off-shell $W$\ boson and also in the $W$-gluon fusion process, called the $t$-channel process. Three searches are conducted -- one separately for an $s$-channel signal, one for a $t$-channel signal, and a combined search. No evidence for electroweak single top quark production is found. Upper limits are placed at the 95\% confidence level at 13.6~pb for the $s$-channel process, 10.1~pb for the $t$-channel process, and 17.8~pb for the sum of the $s$- and $t$-channel processes. Efforts are underway to use more kinematic features of the events in order to separate the signal from background and improve the sensitivity of the searches. [Preview Abstract] |
Monday, April 18, 2005 3:54PM - 4:06PM |
U7.00002: Upper Limits on Cross Sections Using Kinematic Distributions and the Single Top Quark Search at D{\O} Supriya Jain We discuss a statistical analysis method using kinematic distributions to compute the upper limits cross sections based on Bayesian statistics. This method uses a matrix that describes the global uncertainties and their correlations between signal acceptance and backgrounds, and also considers the uncertainties that change the shape of the distributions. As an example we discuss its application to the single top quark search at $\sqrt{s}=1.96$ TeV in $p\bar{p}$ collisions using data collected by the D{\O} experiment during Run II of the Fermilab Tevatron collider. [Preview Abstract] |
Monday, April 18, 2005 4:06PM - 4:18PM |
U7.00003: Search for Electroweak Production of the Top Quark in the Muon+Jets Channel at D{\O} Daekwang Kau Protons and antiprotons are collided in Run~II of the Fermilab Tevatron at a center of mass energy of 1.96 TeV. We present results of a search for single top quark production in these collisions using a dataset of approximately 230 pb$^{-1}$ collected with the D{\O} detector. This analysis considers the muon+jets final state and makes use of secondary-vertex tagging to identify jets originating from $b$~quarks as well as neural networks to further separate the expected signals from backgrounds. [Preview Abstract] |
Monday, April 18, 2005 4:18PM - 4:30PM |
U7.00004: Electroweak Production of Top Quarks in the Electron+Jets Channel at D{\O} Shabnam Jabeen Electroweak production of the top quark (single top) has yet to be observed. The single top cross section is sensitive to new physics and to the CKM matrix parameter $V_{tb}$. The D\Oexperiment has collected so far more than 350 pb$^{-1}$ of data at $\sqrt{s}= 1.96$ TeV in $p\bar{p}$ collisions during Run II of the Fermilab Tevatron collider. Preliminary results of a search for single top quark production in the top decay channel $t\rightarrow Wb\rightarrow e \nu$+jets are presented. [Preview Abstract] |
Monday, April 18, 2005 4:30PM - 4:42PM |
U7.00005: Search for Single Top Quark Production in the Electron+Jets Channel at D{\O} Philip Perea Protons and antiprotons are collided in Run II of the Fermilab Tevatron at a center of mass energy of 1.96 TeV. We present results of a search for single top quark production in these collisions using a dataset of approximately 230 pb$^{-1}$ collected with the D{\O} detector. This analysis considers the electron+jets final state and makes use of secondary-vertex tagging to identify jets originating from $b$~quarks as well as neural networks to further separate the expected signals from backgrounds. [Preview Abstract] |
Monday, April 18, 2005 4:42PM - 4:54PM |
U7.00006: Search for Right-Handed Helicity $W$ Bosons in Top Quark Decays at D{\O} Bryan Gmyrek Within the Standard Model, the helicity of the $W$~boson in the top quark decay is given by the V--A coupling. As the top quark is by far the heaviest of all fermions, some models predict an additional V+A coupling between the top quark and the $W$~boson. 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 present a search for right-handed helicity $W$ bosons in top quark decays using the lepton+jets decay channel. The data were collected by the D\O\ experiment during Run II of the Fermilab Tevatron. The $W$ boson helicity is determined using the angular distribution of the lepton in the $W$ rest-frame with respect to the $W$ direction. A limit on the fraction of right-handed $W$ bosons is reported along with a discussion of systematic uncertainties. [Preview Abstract] |
Monday, April 18, 2005 4:54PM - 5:06PM |
U7.00007: Search for $t\bar{t}$\ Resonance at CDF with kinematics. Brandon Parks Currently, the Fermilab Tevatron is the only accelerator capable of producing the top quark. More than $340~pb^{-1}$ of data has been collected using the Collider Detector at Fermilab. This data sample provides an opportunity to search for rare processes involving top quarks. One such process is the decay of a heavy object into top-antitop pairs. We present a method to search for a top-antitop quark resonance using kinematic features of the events. In addition to the status of the current search, we will present the prospects for the future. [Preview Abstract] |
Monday, April 18, 2005 5:06PM - 5:18PM |
U7.00008: Search for Top-Antitop Pair production via a non-Standard Model resonance Valentin Necula We examine the invariant mass spectrum of top-antitop pairs in the Run 2 CDF data from ppbar collisions at Tevatron. We search for non-standard model resonance states in the lepton+jets final state channel. We use an event reconstruction technique that uses production and decay information to increase the sensitivity for discovery. [Preview Abstract] |
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