Measurement of W-Boson Helicity Fractions in Top-Quark Decays Using costheta*

TL;DR

This paper measures the fractions of different W-boson helicities in top-quark decays using reconstructed top-antitop events, providing insights into the Wtb vertex structure with data from the Fermilab Tevatron.

Contribution

It presents two methods for measuring W-boson helicity fractions in top decays using 1.9 fb-1 of proton-antiproton collision data, enhancing understanding of top-quark decay dynamics.

Findings

Measured W-boson helicity fractions with two methods.

Results are consistent with Standard Model predictions.

Provides constraints on Wtb vertex couplings.

Abstract

Fully reconstructed top-antitop-events are used to determine the fractions of right-handed and longitudinally polarized W bosons produced in top-quark decays. The helicity fractions are sensitive to the couplings and the Dirac structure of the Wtb vertex. This paper reports measurements of the W-boson helicity fractions from two different methods using data corresponding to an integrated luminosity of 1.9 fb-1 of proton-antiproton collisions collected by the CDF II detector operating at the Fermilab Tevatron.