Time-dependent dalitz plot analysis of B0 → K 0S π+π-

We perform a time-dependent Dalitz plot analysis of B0 → K0 S π+π- in order to extract the CP violation parameters of f0(980)K0 S and ρ0(770)K0 S and direct CP-asymmetries of Kz.ast;+(892)π-. The results are obtained from a data sample of (383 ± 3) × 106 BB decays, collected with the BABAR detector at the PEP-II asymmetric-energy B factory at SLAC. The measured values of 2βeff in B0 decays to f0(980)K0S and ρ0(770)K0 S are (89+22-20 ± 5 ±8) and (37+19 -17 ± 5 ±6), respectively, where the first quoted uncertainty is statistical, the second is systematic and the third is Dalitz plot signal model uncertainty. We measure the significance of 2βeff (f0(980)K0S) 6= 0 to be 4.3 σ. In decays to Kz.ast;(892)π we find ACP = -0.18 ± 0.10 ± 0.03 ± 0.03. The measured phase difference between the decay amplitudes of B0 → Kz.ast;+(892)π- and B0 → Kz.ast;-(892)π+ is (-164 ± 24 ± 12 ± 15). All results are preliminary.