$B^0\to K^0_SK^0_S$ branching fraction and direct CP asymmetry

We present the first evidence for the penguin-dominated decay $B^0\to K^0 \bar{K^0}$ using a data sample of approximately 227 million $\Upsilon(4S)\to B\bar{B}$ pairs collected by the BaBar detector at the PEP-II asymmetric-energy B Factory at SLAC. We reconstruct the neutral kaons in the channel $K^0\to K^0_S\to\pi^+\pi^-$, and we use a maximum likelihood fit incorporating kinematic and event-shape information to extract the signal yield.