Measurement of the branching fraction for D0->Ks0Ks0pi+pi- and search for CP violation via T-odd triple product asymmetry*

We measure the branching fraction for $D^{0} \rightarrow K_{s}^{0} K_{s}^{0} \pi^{+} \pi^{-}$ decays and also search for $CP$ violation by measuring a $T$-odd triple-product asymmetry. We use a data sample corresponding to an integrated luminosity of 932 fb$^{-1}$. The data were collected by the Belle detector at the KEKB $e^{+}e^{-}$ collider running at the $\Upsilon(4S)$ and $\Upsilon(5S)$ resonances. In the Standard Model (SM), $CP$ violation is expected to be very small in charm decays; thus an observed signal could indicate physics beyond the SM. The $T$-odd observable measured is $C^{}_{T} = \vv{P}_{K_{s}^{0}} \cdot (\vv{P}_{\pi^{+}} \times \vv{P}_{\pi^{-}})$. The difference in this observable between $D^{0}$ and $\overline{D}{}^0$ decays provides a measure of $CP$ violation free from strong interaction effects.