Time-dependent amplitude analysis of B0 --> K0S pi+ pi-

We perform a time-dependent amplitude analysis of $B^0 \to K^0_Sπ^+π^-$ decays to extract the CP violation parameters of $f_0(980) K^0_S$ and $ρ^0(770) K^0_S$ and the direct CP asymmetry of $K^{*+}(892) π^-$. The results are obtained from a data sample of $(383 \pm 3) \times 10^6$ $B\bar{B}$ decays, collected with the BABAR detector at the PEP-II asymmetric-energy $B$ factory at SLAC. We find two solutions, with an equivalent goodness-of-fit. Including systematic and Dalitz plot model uncertainties, the combined confidence interval for values of the CP parameter $β_{eff}$ in $B^0$ decays to $f_0(980) K^0_S$ is $18^o < β_{eff} < 76^o$ at 95% confidence level (C.L). CP conservation in $B^0$ decays to $f_0(980) K^0_S$ is excluded at $3.5σ$ including systematic uncertainties. For $B^0$ decays to $ρ^0(770) K^0_S$, the combined confidence interval is $-9^o < β_{eff} < 57^o$ at 95% C.L. In decays to $K^{*+}(892) π^-$ we measure the direct CP asymmetry to be $A_{CP}=-0.20 \pm 0.10 \pm 0.01 \pm 0.02$. The measured phase difference (including $B^0\bar{B}^0$ mixing) between decay amplitudes of $B^0 \to K^{*+}(892) π^-$ and $\bar{B}^0 \to K^{*-}(892) π^+$, excludes the interval $-137^o < ΔΦ(K^{*+}(892) π^-) < -5^o$ at 95% C.L.

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