Measurement of the helicity of W bosons in top-quark decays

Authors

A. Abulencia, University of Illinois, Urbana
Kenneth A. Bloom, University of Nebraska-LincolnFollow
CDF Collaboration

Date of this Version

6-5-2006

Comments

Published by American Physical Society. Phys. Rev. D 73, 111103(R) (2006). http://prd.aps.org. Copyright © 2006 American Physical Society. Permission to use.

Abstract

We measure the branching fraction of the top quark to longitudinally and right-handed polarized W bosons, F₀ and F₊, using approximately 200 pb^-1 of p̅p collisions collected by the CDF II detector. We analyze two quantities sensitive to the W helicity: the invariant mass of the charged lepton and the bottom quark jet in the decay t → Wb → ℓνb (where ℓ = ℯ or μ), and the transverse momentum of the charged lepton. Constrained fits yield F₀ = 0.7̅4̅_-0.34^+0.22, and F₊ < 0.2̅7̅ at the 95% confidence level. These measurements are consistent with the standard model predictions.