Measurement of the Time-Dependent CP Asymmetry in the B0 --> Phi K0 Decay

TL;DR

This paper reports a measurement of the time-dependent CP asymmetry in B0 decays to Phi K0 using data from the BaBar detector, providing insights into CP violation in the B-meson system.

Contribution

First measurement of CP asymmetry parameters in B0 --> Phi K0 decays using a large data sample at BaBar.

Findings

Measured CP-violation parameters: S = 0.47 +/- 0.34 (stat) +0.08/-0.06 (syst)

Observed no significant CP violation within uncertainties

Demonstrated reconstruction of CP eigenstates Phi K0_S and Phi K0_L

Abstract

We present a measurement of the time-dependent CP asymmetry for the neutral B-meson decay B0 --> Phi K0. We use a sample of approximately 114 million B-meson pairs taken at the Upsilon(4S) resonance with the BaBar detector at the PEP-II B-meson Factory at SLAC. We reconstruct the CP eigenstates Phi K0_S and Phi K0_L where Phi --> K+ K-, K0_S --> pi+ pi-, and K0_L is observed via its hadronic interactions. The other B meson in the event is tagged as either a B0 or B0-bar from its decay products. The values of the CP-violation parameters are S = 0.47 +/- 0.34 (stat) +0.08/-0.06 (syst) and C = 0.01 +/- 0.33 (stat) +/- 0.10 (syst).