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Top Properties
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Measurement of forward-backward asymmetry in top quark production at CDF
Speaker: Glenn Strycker (CDF Collaboration) PDF
We measure a forward-backward charge asymmetry in the rapidities
of top quarks produced in $p\bar p$ collisions at $\sqrt s$=1.96
TeV. The $t\bar t$ kinematics are reconstructed in ~800
lepton+jets events collected in a 3 $fb^{-1}$ exposure with CDF
detector at Fermilab. We present two independent techniques -- a
model independent unfold and a likelihood fit to a linear
asymmetry in the production angle $(1+Acos(\alpha))$ -- that give
consistent results for the parton level asymmetry in both the
laboratory and
$t\bar t$ rest frames. The results are compared to
the small charge asymmetry expected in QCD at NLO.
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Measurement of the top pair production cross section in the dilepton decay channel at CDF
Speaker: Chang-Seong Moon (CDF Collaboration) PDF
We present a measurement of the $t\bar{t}$ production cross
section in $p\bar{p}$ collisions at $\sqrt{s}$ = 1.96 TeV using
2.8 fb$^{-1}$ of data collected by the CDF detector at the
Fermilab Tevatron. We use $t\bar{t}$ dilepton events
reconstructed with missing transverse energy and jets assuming
top quark mass $m_t$ = 175 GeV/c$^2$. We measure $\sigma_{
t\bar{t}} = 6.13 \pm 0.88_{stat} \pm 0.40_{syst} \pm 0.38_{lumi}$ pb.
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Measurement of the $W$ boson helicity fractions in $t\overline{t}$ production in dilepton channel at CDF
Speaker: Roman Lysak (CDF Collaboration) PDF
Abstract: We present a $t\bar{t}$\ production cross section measurement in the
multi-jet final state channel from collisions of protons and
anti-protons at $\sqrt{s}$= 1.96 TeV at the CDF II Detector at the Fermilab Tevatron.
We study events with high missing transverse energy and we select those that contain jets that are identified in the silicon vertex detector as originating from b-quarks using a neural network algorithm.
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Search for non-standard model top antitop resonance production in the all-hadronic channel at CDF
Speaker: Yuri Oksuzian (CDF Collaboration) PDF
We present an updated result of a search for resonant top-antitop
pair production and subsequent decay in the all-hadronic channel.
We examine the top-antitop invariant mass spectrum observed in
CDF data from 1.96 TeV $p\overline p$ collisions at the Fermilab
Tevatron. We apply a powerful reconstruction technique where the
observed event kinematics are constrained according to the full
standard model top-antitop production and decay matrix element.
This technique provides excellent mass resolution. Also,
probability densities from the per-event matrix element
calculation are used as discriminants to reduce and control the
large backgrounds of the all-hadronic channel.
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Single Top
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Measurement of the single top cross section
Speaker: Bruno Casal (CDF Collaboration) PDF
We present recent results from searches for single-top-quark
production and single-top polarization studies using 3.2
$fb^{-1}$ of
data accumulated with the CDF detector at the Fermilab Tevatron. We
select events with one charged lepton, large missing transverse
energy, and two or three jets, where at least one jet is
identified as a b-quark jet using displaced secondary-vertex information from the
CDF silicon detector. We employ a boosted decision tree analysis
technique and a neural-network jet-flavor separator to improve
separation of signal and background and greatly improve the
sensitivity of our search.
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Measurement of the single top production cross section in the transverse missing energy plus jets sample
Speaker: Karolos Potamianos (CDF Collaboration) PDF
Standard model top quarks are produced mostly in pairs at the
Tevatron through the strong force. However, the production of a
single top quark per process is allowed through electroweak
processes. We present a measurement of the the standard model
single top production cross-section in proton-anti protons
collisions at 1.96 TeV center of mass energy. The data collected
with the CDF II detector at the Tevatron collider at Fermilab
correspond to an integrated luminosity of 2.1 $fb^{-1}
$. Until now, Tevatron experiments searched for single top only in events
where one high energy electron or muon has been identi?ed, to
suppress the huge QCD background. Here, we look for the first
time at events where no electron or muon has been identi?ed, and
where tau leptons decay hadronically and are reconstructed as
jets in the calorimeter. Thus, we consider a signature of two
b-jets, no leptons, and missing transverse energy. We present
preliminary results as well as ongoing efforts in this search.
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Measurement of the polarization of singly-produced top quarks in CDF
Speaker: Ji-Eun Jung (CDF collaboration) PDF
We present a measurement of the polarization of singly-produced
top quarks in $p\bar p$ collisions using 3 $fb^{-1}$ of data
collected with the CDF detector. Single top quarks are expected
to be produced via virtual $W$ boson exchange in $t$-channel and
$s$-channel processes. The standard model predicts a left-handed
vector coupling at the $Wtb$ vertex, but extensions allow a
right-handed vector coupling. We measure separately
the left- and right-handed couplings, and thus the polarization, by
measuring the angular distributions of the top quark's decay
products.
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Top Mass
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Measurement of the top quark mass using quantities that are independent of the jet energy scale at CDF
Speaker: Ford Garberson (CDF collaboration) PDF
We will present two techniques for measuring the top quark mass
in the lepton plus jets channel using quantities independent of
the jet energy scale uncertainty. One technique exploits the
correlation of the transverse decay length of $b$-tagged jets
with the top mass, and the other exploits the correlation of the
transverse momentum of the lepton in the same events with the top
mass. While these results are still statistically limited, their
precision will improve with added data at the Teva
tron and the
LHC. Further, since their correlation to more conventional top
mass measurement techniques is small, they will help to reduce
the overall uncertainty on the top mass in combination with other
results.
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Top quark mass measurement in the lepton+jets and dilepton channels at CDF using mT2
Speaker: Jian Tang (CDF Collaboration) PDF
A measurement of top quark mass at CDF will be presented using a
3.0 $fb^{-1}$ data sample in both lepton+jets and dilepton
channels. In the lepton+jets channel, we determine the
reconstructed top quark mass by minimizing the $\chi^{2}$ for the
overconstrained kinematic system, and we also measure the
hadronically decaying $W$ boson mass to provide an $in-situ$
improvement in the determination of jet energy scale. In the
dilepton channel, we replace our old observable $H_T$, which is
the scalar sum of transverse energy of all particles in one
event, with a new observable $m_T^2$, which is used in $W$ mass
measurements and SUSY searches. We find a satisfying improvement
in our result of top quark mass measurement using this new
observable.
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Measurement of the top quark mass in the lepton+track sample at CDF
Speaker: Marco Trovato (CDF Collaboration) PDF
We report on a measurement of the top quark mass in the
lepton+track sample of events at CDF. This new selection was
applied to $t\bar t$ candidates in the dilepton channel in order
to increase the acceptance by relaxing the cuts on one lepton. To
constrain the event kinematics the azimuthal angles of the two
neutrinos are assumed as known and the top quark mass is
reconstructed accordingly. The full neutrino phase space is
scanned and $\chi^2$-dependent weights are given to the solutions
in order to build a preferred mass for each event. The integrated
luminosity of the data sample is 2.9 fb$^{-1}$. 328 candidate
events were reconstructed and fitted as a superposition of signal
and background. In a constrained fit with 145.0 $\pm$ 17.3
background events as determined in the production cross section
studies we measure $m_t$= 165.5 $\pm^{3.4}_{3.3}$ (stat) $\pm$ 3.1
(syst.) GeV/c$^2$.
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A matrix element analysis measurement of the top quark mass in the lepton + jets channel with an in situ jet energy scale measurement
Speaker: Daryl Hare (CDF Collaboration) PDF
We measure the top quark mass from $p\bar p$ collisions at 1.96
TeV at CDF in the lepton + jets channel with at least 3 $fb^{-1}$
of data. Events require a single lepton, missing transverse
energy, and 4 jets of which at least one must be tagged as a b
jet. We use a 2D unbinned likelihood fit based on per-event
probabilities calculated from leading-order signal ($t\bar t$)
and background ($W$+jets) matrix elements. Our measurement is
dependent upon the energy scale of calorimeter jets, so we
measure this scale in-situ by constraining the invariant mass of
the two jets from to the W boson mass.
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