Search for right-handed<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>W</mml:mi></mml:math>bosons in top quark decay

We present a measurement of the fraction ${f}_{+}$ of right-handed $W$ bosons produced in top quark decays, based on a candidate sample of $t\overline{t}$ events in the lepton+jets decay mode. These data correspond to an integrated luminosity of $230\text{ }\text{ }{\mathrm{pb}}^{\ensuremath{-}1}$, collected by the D0 detector at the Fermilab Tevatron $p\overline{p}$ Collider at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$. We use a constrained fit to reconstruct the kinematics of the $t\overline{t}$ and decay products, which allows for the measurement of the leptonic decay angle ${\ensuremath{\theta}}^{*}$ for each event. By comparing the $\mathrm{cos}{\ensuremath{\theta}}^{*}$ distribution from the data with those for the expected background and signal for various values of ${f}_{+}$, we find ${f}_{+}=0.00\ifmmode\pm\else\textpm\fi{}0.13(\mathrm{\text{stat}})\ifmmode\pm\else\textpm\fi{}0.07(\mathrm{\text{syst}})$. This measurement is consistent with the standard model prediction of ${f}_{+}=3.6\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$.

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