Time-dependent amplitude analysis of B0→K0Sπ+π−

Abstract

We perform a time-dependent amplitude analysis of B 0 → K 0 S π + π − decays to extract the C P violation parameters of f 0 ( 980 ) K 0 S and ρ 0 ( 770 ) K 0 S and the direct C P asymmetry of K * + ( 892 ) π − . The results are obtained from a data sample of ( 383 ± 3 ) × 10 6 B ¯¯¯ 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 C P parameter β eff in B 0 decays to f 0 ( 980 ) K 0 S is 18 ° < β eff < 76 ° at 95% confidence level (C.L). C P conservation in B 0 decays to f 0 ( 980 ) K 0 S is excluded at 3.5 standard deviations including systematic uncertainties. For B 0 decays to ρ 0 ( 770 ) K 0 S , the combined confidence interval is − 9 ° < β eff < 57 ° at 95% C.L. In decays to K * + ( 892 ) π − we measure the direct C P asymmetry to be A C P = − 0.20 ± 0.10 ± 0.01 ± 0.02 . The measured phase difference (including B 0 ¯¯¯ B 0 mixing) between decay amplitudes of B 0 → K * + ( 892 ) π − and ¯¯¯ B 0 → K * − ( 892 ) π + , excludes the interval − 137 ° < Δ Φ ( K * + ( 892 ) π − ) < − 5 ° at 95% C.L.