Search for the decay D0→γγ and measurement of the branching fraction for D0→π0π0

Résumé fourni par la source

We search for the rare decay of the ${D}^{0}$ meson to two photons, ${D}^{0}\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma}$, and present a measurement of the branching fraction for a ${D}^{0}$ meson decaying to two neutral pions, $B({D}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0})$. The data sample analyzed corresponds to an integrated luminosity of $470.5\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ collected by the BABAR detector at the PEP-II asymmetric-energy ${e}^{+}{e}^{\ensuremath{-}}$ collider at SLAC. We place an upper limit on the branching fraction, $B({D}^{0}\ensuremath{\rightarrow}\ensuremath{\gamma}\ensuremath{\gamma})<2.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$, at 90% confidence level. This limit improves on the existing limit by an order of magnitude. We also find $B({D}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0})=(8.4\ifmmode\pm\else\textpm\fi{}0.1\ifmmode\pm\else\textpm\fi{}0.4\ifmmode\pm\else\textpm\fi{}0.3)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$.

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