Measurement of the Top quark Mass at CDF using a Matrix Element Technique
We report a measurement of the top quark mass obtained from
proton-antiproton collisions at a center-of-mass energy of 1.96 TeV
at the Fermilab Tevatron using the CDF II detector The measurement
relies on a using a matrix
element integration method to calculate a signal likelihood, as well as a neural network discriminat
to distinguish signal from backgrounds. The result is currently the
single most precise measurement of the top quak mass in the world.
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Direct measurements of the top quark mass, width, and mass difference between the top and anti-top quark using the template method at CDF
We present measurements of the top quark mass, width, and mass difference between the top and anti-top quark in the lepton+jets channel using the CDF II detector at Fermilab's Tevatron. We developed the template method with non-parametric kernel density estimation which uses multidimensional observables without parametrization and produces probability density functions of signal and background events. By applying different signal modelings and observables for each measurement, we extract the properties of the top quark from CDF data.
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A Matrix Element Analysis measurement of the Top Quark Mass in the hadronic tau + jets channel with an in situ Jet Energy Scale measurement from W to jj.
We use a 2D unbinned likelihood fit, as used in previous precision top quark mass measurements, with events from lepton + jet top quark decays where the lepton has been identified as a hadronically decaying tau. We use ppbar collisions at 1.96 TeV at CDF. Events require a single lepton identified as a hadronic tau, missing Et, and 4 jets of which at least one must be tagged as a b jet. The likelihood fit is based on per-event probabilities calculated from leading-order signal (ttbar) and background (W+jets) matrix elements. Our goal is to directly identify this final state for the first time as well as provide a top quark mass measurement in this decay channel.
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Measurement of the Ratio of the Top Pair
to Z Boson Cross Section and Precise Extraction of the Top Cross Section
The ratio of the top pair cross section with the Z boson cross section
has been measured in over 4 fb-1 of collected data from the high Pt
lepton triggers. The top cross section is
measured in the lepton plus jets channel using two complimentary
methods, a b-jet tagging measurement and a topological approach. By
multiplying the ratios by the well-known theoretical Z/gamma cross
section, the extracted t-tbar cross sections are effectively
insensitive to the uncertainty on luminosity. The results are the
most precise measurements of the t-tbar cross section in the world to date.
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Measurement of the top cross section in the lepton+jets channel using simultaneous kinematic fits in 2.7 fb-1 of CDF data
We measure both the t-tbar cross section and the background
level of W+jets, QCD, and electroweak processes using a simultaneous
kinematic fit to the b-tagged lepton + jets data. This is the first
application of a procedure of this kind.
The top cross section and Monte Carlo simulation K factors for W+jets
processes are found to be in good agreement with existing measurements
using other procedures. This approach has an added advantage that many
systematic uncertainties are measured in-situ and inversely scale with
integrated luminosity similarly to statistical uncertainties.
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Measurement of the single top production cross section at CDF
We present the most precise measurement of electroweak single top quark production by the CDF experiment. Candidate events are selected for further classification by four parallel analysis techniques: one using a likelihood discriminant, one using a matrix-element discriminant, one using decision trees, and one using a neural network. The results of these four analyses are combined in order to improve the expected sensitivity. We also present the most current value of the CKM matrix element Vtb.
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Measurement of top pair spin correlations using CDF Run II data
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
measurements of the t-tbar spin correlation using lepton+jet and
dilepton events in over 4 fb-1 of CDF data. The results are
combined and the result is the most precise determination of t-tbar spin
correlation to date.
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Latest CDF Results on the Measurement of W-Boson Polarization in Top-quark Decay
The top quark is the most massive fundamental particle observed by experiment. Due to its large mass, the top quark decays before forming a bound state and provides a unique opportunity to study the properties of a ``bare'' quark. In the Standard Model (SM) the top quark decays via the weak interaction into a W boson and a b quark most of the time, and the W boson is expected to have longitudinal, left-handed and right-handed polarization fractions of ~0.70, ~0.30 and 0.0, respectively. In beyond the SM scenarios, significant deviations from the SM expectation are possible due to the presence of anomalous couplings in the tWb vertex. I will present the latest CDF results probing the tWb vertex by measurement of W-Boson polarization in top-pair decay.
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Measurement of the Forward Backward asymmetry in top-antitop quark pairs at CDF
A method of reconstructing t-tbar events in the lepton plus jets mode
is applied to a measurement of the forward backward asymmetry in t-
tbar pair production at CDF. The measurement is a test of discrete
symmetries in t-tbar production and strong interactions at large
Q^2. In the present data set it is potentially sensitive to the
presence of parity-violating production channels such as a massive
Z'- like boson or new physics within strong interactions. We present
a measurement of the top quark forward-backward asymmetry in over 5
fb-1 of collected CDF Run II data.
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Towards Boosted Top: First Study of Boosted Jet Substructure at CDF
We report preliminary results from a study of the properties of highly boosted and massive jets produced at the Tevatron and recorded by the CDF II Detector. The data consist of several thousand jets with transverse momenta greater than 400 GeV/c collected in a data sample of 5 fb-1. The detailed properties of these jets have been measured, including the mass of the jet and several variables such as angularity and planar flow that have been proposed for studies of QCD in the perturbative region and its showering mechanism, as well as discriminants between massive jets produced via QCD radiation and those arising from the decay of massive particles. We also examine these jets for evidence of high transverse momentum top quark production.
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Search for Heavy Top-like Quarks Using Lepton Plus Jets Events in 1.96-TeV ppbar Collisions
Fifteen years since the discovery of top at the Tevatron, with the large Run 2 dataset in hand and plenty of analysis experience, we have now reached the point where we can perform in-depth examinations of the top quark event sample for evidence of physics beyond the Standard Model. We present a search for a massive quark (t') decaying to Wq or Wb and thus mimicking the top quark decay signature. We use the reconstructed mass of the t' quark and the scalar sum of the transverse energies in the event to discriminate possible new quarks or other particles from Standard Model processes, and set limits on a standard 4th generation t' quark.
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Search for singly produced heavy quarks at the Tevatron
We present a search for new vector-like heavy quarks in p-pbar collisions at sqrt(s)=1.96 TeV. We do a model-independent search for singly produced heavy quarks decaying to a W boson and a light flavor quark in events with an electron or muon, missing energy, and two hadronic jets. First results in a data sample corresponding to 4.6 /fb of integrated luminosity collected by the CDF detector are presented.
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Search for Light Higgs Boson from Top Quark Decays at CDF
We present a search for light (with mass below 2m_b) NMSSM pseudo-scalar Higgs boson A originating from top quark decays t->H+b -> W*Ab Under assumption that A decays into tau-tau, we search in events with lepton + >=3 jets and >= 1 b-tag for an additional isolated track in the Pt range from 3 to 20 GeV/c. Using a fit to the isolated track Pt spectrum we derive limits on the branching ratio of t->H+b for various H+ and A masses.
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Searches for resonant top-antitop production at CDF
We describe searches for resonant top-antitop production in over 4fb-1 of 1.96 TeV proton-antiproton collisions at the Tevatron, using data collected by the CDF collaboration. Resonant top pair production could arise from the decays of massive Z-like bosons in extended gauge theories, KK states of the gluon or Z, axigluons, topcolor, and other BSM theories. We use different techniques to study the top- antitop invariant mass spectrum and set model independent limits on new resonant top- antitop production mechanisms that would appear as bumps in invariant mass.
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