Speaker
Konstantinos Vellidis
(University of Athens (GR))
Description
The study of the dynamics of top-quark pair production in
proton-proton and proton-antiproton collisions plays an important role
in the understanding of parton interactions at large Bjorken-x. It
tests the assumptions of the standard model and of quantum
chromodynamics at the electroweak scale and beyond. The CDF data set
is an ideal sample for measuring observables sensitive to the dynamics
of top-quark pair production, given the excellent understanding of
detector performance and the unique proton-antiproton initial
state. We present recent measurements of such observables from
CDF. These include the direct measurement of the ratio R of the
branching fraction of top-quark decaying to W + b-quark over the
branching fraction of top-quark decaying to W + any quark flavor. The
measurement uses data corresponding to 7.5/fb of integrated luminosity
in the lepton+jets decay channel. The ratio R constrains the |V_tb|
element of the CKM matrix. We also present a measurement of the spin
correlation coefficient of the top-quark pair, which can be directly
measured uniquely in the top-pair system thanks to the very short life
time of the top-quark. This measurement uses data corresponding to
5.1/fb of integrated luminosity in the dilepton decay
channel. Finally, we present a study of the top-quark pair production
asymmetries in the lepton+jets channel using the full CDF Run II data
set which corresponds to an integrated luminosity of 8.7/fb. The study
includes the measurement of the cross section differential in the
top-pair rapidity difference, the measurement of the inclusive
forward-backward asymmetry A_FB, as well as the measurement of A_FB as
a function of the rapidity difference and of the invariant mass of the
top-pair system. The production asymmetries are sensitive to the
top-quark pair production mechanism, thus constraining quantum
chromodynamics at higher order and testing for possible new physics.
Primary author
Konstantinos Vellidis
(University of Athens (GR))
