Measurement of β s at CDF

The latest results for the measurement of the CP violating phase βs in B 0 → J/ψφ decays, from 5.2 fb −1 integrated luminosity of CDF data are presented. For the first time, this measurement includes the contribution of B 0 → J/ψK + K − or B 0 → J/ψ f0 events to the signal sample, where the f0 and non-resonant K + K − are S-wave states. Additional improvements to the analysis include more than doubling the signal sample, improved selection and particle ID, and fully calibrated flavour tagging for the full dataset. Additionally, the world’s most precise single measurements of the B 0 lifetime, τs, and width difference, ΔΓs are given.