Measurement of CP Violation in B<sup>0</sup> to ΦK<sup>0</sup>, and of Branching Fraction and CP Violation in B<sup>0</sup> → F<sub>0</sub>(980) K$0\atop{S}$

Abstract

The authors measure the time-dependent CP asymmetry parameters in B0 → K+K-K0 based on a data sample of approximately 277 million B-meson pairs recorded at the Y(4S) resonance with the BABAR detector at the PEP-II B-meson Factory at SLAC. They reconstruct two-body B0 decays to Φ(1020)K$0\atop{S}$ and Φ(1020)K$0\atop{L}$. Using a time-dependent maximum-likelihood fit, they measure sin2βeff(ΦK0) = 0.48 ± 0.28 ± 0.10, and C(ΦK0) = 0.16 ± 0.25 ± 0.09, where the first error is statistical, and the second is systematic. They also present measurements of the CP-violating asymmetries in the decay B0 → f0(→ {pi}+π-)K$0\atop{S}$. The results are obtained from a data sample of 209 x 10{sup 6} Y(4S) → B$\bar{B}$ decays, also collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. From a time-dependent maximum-likelihood fit they measure the mixing-induced CP violation parameter S(f0(980)K$0\atop{S}$) = - sin 2βefff0(980)K$0\atop{S}$ = -0.95$+0.32\atop{-0.23}$ ± 0.10 and the direct CP violation parameter C(f0(980)K$0\atop{S}$) = - 0.24 ± 0.31 ± 0.15, where the first errors are statistical and the second systematic. Finally, they present a measurement of the branching fraction of the decay B0 → f0(→ π+π-)K$0\atop{S}$. From a time-dependent maximum likelihood fit to a data sample of 123 x 106 Y(4S) → B$\bar{B}$ decays they find 93.6 ± 13.6 ± 6.4 signal events corresponding to a branching fraction of β(B0 → f0(980)(→ π+π-)K0) = (6.0 ± 0.9 ± 0.6 ± 1.2) x 10-6, where the first error is statistical, the second systematic, and the third due to model uncertainties.