Bulletin of the American Physical Society
APS April Meeting 2010
Volume 55, Number 1
Saturday–Tuesday, February 13–16, 2010; Washington, DC
Session Y9: Top Quark Physics II |
Hide Abstracts |
Sponsoring Units: DPF Chair: Nick Hadley, University of Maryland Room: Maryland A |
Tuesday, February 16, 2010 1:30PM - 1:42PM |
Y9.00001: Top quark mass measurement in the lepton+jets and dilepton channels at CDF using a template method Jian Tang We present a measurement of the top quark mass using the CDF detector at the Fermilab Tevatron in the lepton + jets and two leptons final states using a template method. In the lepton + jets channel, we introduce a 3-dimensional template using non-parametric kernel density estimation. Two of the observables have been used in a previous analysis which are the reconstructed top quark mass in each event obtained by minimizing a $\chi^2$ for the overconstrained kinematic system and dijet mass of the hadronically decaying W boson in the same event sample, that provides an in situ improvement in the determination of the jet energy scale. The 3rd observable is the reconstructed top quark mass with the 2nd best $\chi^2$ in the kinematic fit. In the dilepton channel, we use the reconstructed top quark mass determined using the neutrino weighting method and mT2, a variable related with the transverse mass in events with two missing particles. In order to increase the lepton acceptance in the lepton+jet events, a new lepton category was included from data collected by a trigger that requires the presence of missing energy and two jets. By increasing the statistics and the development of the 3-dimensional template method, we have significant improved the final result. [Preview Abstract] |
Tuesday, February 16, 2010 1:42PM - 1:54PM |
Y9.00002: Measurement of Top Quark Mass in the Lepton+Jets Channel using Ideogram Method with D0 RunII data Vivek Parihar We provide an update to the precision measurement of top quark mass using the ideogram technique. We select events with one charged lepton (e or mu), missing transverse energy and jets in the final state. These events are then reconstructed using a kinematic fit. The event likelihood thus calculated entails information from a low-bias topological discriminant and the kinematically fitted mass templates. The likelihood also entails the probability that the event was a signal or background kind. The invariant mass of jets from hadronically decaying W boson in top like events is used to fit the jet energy scale in situ. [Preview Abstract] |
Tuesday, February 16, 2010 1:54PM - 2:06PM |
Y9.00003: Measurement of the top quark mass using the Neutrino Weighting approach Yuriy Ilchenko We present an updated measurement of the top quark mass using the Neutrino Weighting approach. The measurement is based on about 5/fb of top quark pairs candidate events with two final state leptons taken with the D0 detector at the Tevatron collider. We integrate over expected neutrino rapidity distributions and compare the vector sum of the two neutrinos with the missing energy to extract the top quark mass. [Preview Abstract] |
Tuesday, February 16, 2010 2:06PM - 2:18PM |
Y9.00004: Extracting the Mass of the Top Quark from All-Jet Events in D0 Data Gianluca Petrillo Six-jet events arising from decays of $t-\bar{t}$ pairs in which both tops decay into a $W$ boson and a $b$ quark, and both $W$s decay into quark-antiquark pairs, constitute a potentially rich source of completely reconstructed top quarks. Despite the large background from pure jet production, these events form an excellent sample of data for measuring the mass of the top quark. But, even when two of the jets are tagged as likely descending from $b$ quarks, the background is still large, and the mass analysis is complicated by uncertainties in assigning the four other jets to their progenitor quarks. We describe a mass extraction technique that addresses these issues, and present preliminary results from applying the method to $5.4 \mathrm{fb}^{-1}$ data recorded by the D{\O} experiment at the Fermilab Tevatron. [Preview Abstract] |
Tuesday, February 16, 2010 2:18PM - 2:30PM |
Y9.00005: Measurement of the top quark electric charge JeongKu 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 anti-b jet charge templates we get by applying a jet charge algorithm to b tagged jets. In this talk, we present the measurement of the top quark charge using top quark pair events in the lepton+4jets final state with two identified b-jets, using 5.4/fb of data recorded with the D0 detector at the Fermilab Tevatron collider. [Preview Abstract] |
Tuesday, February 16, 2010 2:30PM - 2:42PM |
Y9.00006: Measurement of the top quark charge at CDF Pavol Bartos Since the discovery of the top quark at Fermilab in 1995, the CDF collaboration has studied and measured many of its properties. One of the fundamental properties is the charge. The Standard Model predicts the top quark charge to be +2/3, but there is also an alternative theory arguing that the observed quark is a fourth generation quark with charge -4/3. We present the results of the top quark charge measurement via its decay products. A charge track weighting technique has been used to determine the b-jet charge and the CDF kinematic fitter has been exploited to determine the lepton - b-jet assignment in the lepton+jet case and an invariant mass cut in the dilepton topology. [Preview Abstract] |
Tuesday, February 16, 2010 2:42PM - 2:54PM |
Y9.00007: Measurement of the helicity fractions of $W$ bosons in $t\bar{t}$ production in dilepton channel at CDF Chang-Seong Moon We present a measurement of the helicity fractions of $W$ bosons in the $t\bar{t}$ candidate events selected from final states where both $W$ bosons are decaying leptonically. The analysis is based on 5 fb$^{-1}$ of data collected by the CDF detector at the Fermilab Tevatron in $p\bar{p}$ collisions at $\sqrt{s}$ = 1.96 TeV. The helicity fractions are determined by a comparison of the cos$\theta*$ distribution between the momentum of the charged lepton in the $W$ boson rest frame and the $W$ momentum in top-quark rest frame with templates corresponding to left-handed, right-handed and longitudinally polarized fractions exclusively. This is the first measurement of the $W$ boson helicity fractions in the dilepton channel using kinematic reconstruction at CDF. [Preview Abstract] |
Tuesday, February 16, 2010 2:54PM - 3:06PM |
Y9.00008: Measurement of the helicity of W bosons in top quark decays Amitabha Das We report on a model-independent measurement of the helicity of W bosons produced in top quark decays based on a 5/fb sample of top quark pair events, collected by the D0 detector at Fermilab, colliding protons and anti-protons at the center of mass energy of 1.96 TeV, in the dilepton and lepton+jets channels. In the standard model, the fraction of longitudinal (right-handed) W bosons is predicted to be 0.7 (0). The deviation from these values would be a clear sign of new physics. The measurement is based upon the angle between the momenta of the down-type fermion and the top quark in the W boson rest frame. [Preview Abstract] |
Tuesday, February 16, 2010 3:06PM - 3:18PM |
Y9.00009: Measurement of the top quark width at CDF Jian Tang We present a measurement of the top quark width using 4.3/fb of data collected with the CDF detector at Fermilab. We use a two dimensional template method in the lepton+jet decay topology. The observables are the reconstructed top quark mass from the minimization of a $\chi^2$ for the overconstrained system, and the invariant mass of the two jets from the W decays, which provides an in situ improvement in the determination of the jet energy scale. We build a Feldman-Counsin (FC) confidence belt using Monte Carlo pseudo experiments to extract the top quark width from data at the $95\%$ confidence level. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700