Search for Top-Quark Production via Flavor-Changing Neutral Currents in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>W</mml:mi><mml:mo>+</mml:mo><mml:mn>1</mml:mn></mml:math>Jet Events at CDF

We report on a search for the non-standard-model process $u(c)+g\ensuremath{\rightarrow}t$ using $p\overline{p}$ collision data collected by the Collider Detector at Fermilab II detector corresponding to $2.2\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$. The candidate events are classified as signal-like or backgroundlike by an artificial neural network. The observed discriminant distribution yields no evidence for flavor-changing neutral current top-quark production, resulting in an upper limit on the production cross section $\ensuremath{\sigma}\mathbf{(}u(c)+g\ensuremath{\rightarrow}t\mathbf{)}&lt;1.8\text{ }\text{ }\mathrm{pb}$ at the 95% C.L. Using theoretical predictions we convert the cross section limit to upper limits on flavor-changing neutral current branching ratios: $\mathcal{B}(t\ensuremath{\rightarrow}u+g)&lt;3.9\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ and $\mathcal{B}(t\ensuremath{\rightarrow}c+g)&lt;5.7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$.

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