Search for the decay of aB0orB¯0meson toK

We present a search for the decay of a ${B}^{0}$ or ${\overline{B}}^{0}$ meson to a ${\overline{K}}^{*0}{K}^{0}$ or ${K}^{*0}{\overline{K}}^{0}$ final state, using a sample of approximately $232\ifmmode\times\else\texttimes\fi{}{10}^{6}$ $B\overline{B}$ events collected with the BABAR detector at the PEP-II asymmetric energy ${e}^{+}{e}^{\ensuremath{-}}$ collider at SLAC. The measured branching fraction is $\mathcal{B}({B}^{0}\ensuremath{\rightarrow}{\overline{K}}^{*0}{K}^{0})+\mathcal{B}({B}^{0}\ensuremath{\rightarrow}{K}^{*0}{\overline{K}}^{0})=({0.2}_{\ensuremath{-}0.8\ensuremath{-}0.3}^{+0.9+0.1})\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$. We obtain the following upper limit for the branching fraction at 90% confidence level: $\mathcal{B}({B}^{0}\ensuremath{\rightarrow}{\overline{K}}^{*0}{K}^{0})+\mathcal{B}({B}^{0}\ensuremath{\rightarrow}{K}^{*0}{\overline{K}}^{0})<1.9\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$. We use our result to constrain the standard model prediction for the deviation of the $CP$ asymmetry in ${B}^{0}\ensuremath{\rightarrow}\ensuremath{\phi}{K}^{0}$ from $\mathrm{sin}2\ensuremath{\beta}$.