Measurements of Top Quark Properties

TL;DR

This paper reports measurements of several top quark properties, including production mechanisms, decay characteristics, and asymmetries, using data from CDF and D0 detectors, with results consistent with the Standard Model.

Contribution

It provides new measurements of top quark production fractions, decay helicities, and asymmetries using large datasets, enhancing understanding of top quark behavior.

Findings

Measured gluon fusion fraction in top pair production: 0.53^{+0.36}_{-0.38}

Determined W boson helicity fractions: f_0=0.49±0.14, f_+=0.11±0.08

Measured forward-backward asymmetry: 0.19±0.07

Abstract

Preliminary results on the measurement of four selected properties of the top quark are presented. The relative fraction of $t\bar{t}$ production through gluon fusion has been measured in the $t\bar{t}$ dilepton decay channel by the CDF Collaboration as $F_{gg}=0.53^{+0.36}_{-0.38}$. Using an integrated luminosity of 2.7 fb$^{-1}$ collected with the CDF II detector, we also determine the $t\bar{t}$ differential cross section with respect to values up to $\sim$1 TeV of the $t\bar{t}$ invariant mass. We present a model-independent measurement of the helicity of $W$ bosons produced in top quark decays, using an integrated luminosity of up to 2.7 fb$^{-1}$ collected by the D0 detector, and find the fraction of longitudinal $W$ bosons $f_0=0.49\pm0.14$, and the fraction of right-handed $W$ bosons $f_+=0.11\pm0.08$. Finally, we measure the parton level forward-backward asymmetry of pair produced top quarks using an integrated luminosity of 3.2 fb$^{-1}$ collected with the CDF II detector, and find $A_{FB}=0.19\pm0.07$. All results are consistent with the predictions of the standard model.