Search for the rare decay $W^{\pm }\to {\pi }^{\pm }+\gamma$ in proton-antiproton collisions at $\sqrt{s}=1.8\mathrm{}\hspace{0.5em}\mathrm{TeV}$

We have searched for the rare decay $W^{\pm }\to {\pi }^{\pm }+\gamma$ in $83\hspace{0.5em}{\mathrm{pb}}^{\mathrm{-}1}$ of data taken in proton-antiproton collisions at $\sqrt{s}=1.8\mathrm{}\hspace{0.5em}\mathrm{TeV}$ with the Collider Detector at Fermilab. We find three events in the signal region and estimate the background to be 5.2±1.5 events. We set a 95% confidence level upper limit of $7\times {10}^{-4}$ on the ratio of partial widths, $\Gamma {(W}^{\pm }\to {\pi }^{\pm }+\gamma )/\Gamma {(W}^{\pm }\to e^{\pm }+\nu ).\mathrm{}$