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Measurement of the Helicity of W Bosons in Top-Quark Decays

A. Abulencia
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Abstract

We measure the branching fraction of the top quark to longitudinally and right-handed polarized $W$ bosons, $F_0$ and $F_+$, using approximately 200 pb$^{-1}$ of $\bar{p}p$ 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 $t\to Wb \to \ellνb$ (where $\ell=e$ or $μ$), and the transverse momentum of the charged lepton. We find $F_0=0.74^{+0.22}_{-0.34}$, and $F_+<0.27$ at the 95% confidence level. These measurements are in agreement with the standard model predictions.

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A. Abulencia. 2005-11-08. Measurement of the Helicity of W Bosons in Top-Quark Decays. https://doi.org/10.1103/physrevd.73.111103

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