6533b82cfe1ef96bd128ea60

RESEARCH PRODUCT

Search for the DecayB+→K+νν¯

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description

We search for the rare flavor-changing neutral-current decay ${B}^{+}\ensuremath{\rightarrow}{K}^{+}\ensuremath{\nu}\overline{\ensuremath{\nu}}$ in a data sample of $82\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ collected with the BABAR detector at the PEP-II $B$-factory. Signal events are selected by examining the properties of the system recoiling against either a reconstructed hadronic or semileptonic charged-$B$ decay. Using these two independent samples we obtain a combined limit of $\mathcal{B}({B}^{+}\ensuremath{\rightarrow}{K}^{+}\ensuremath{\nu}\overline{\ensuremath{\nu}})l5.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ at the 90% confidence level. In addition, by selecting for pions rather than kaons, we obtain a limit of $\mathcal{B}({B}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}\ensuremath{\nu}\overline{\ensuremath{\nu}})l1.0\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ using only the hadronic $B$ reconstruction method.