Paper detail

Measurement of the Bottom-Strange Meson Mixing Phase in the Full CDF Data Set

We report a measurement of the bottom-strange meson mixing phase β_s using the time evolution of B0_s -> J/ψ(->μ+μ-) ϕ(-> K+ K-) decays in which the quark-flavor content of the bottom-strange meson is identified at production. This measurement uses the full data set of proton-antiproton collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity. We report confidence regions in the two-dimensional space of β_s and the B0_s decay-width difference ΔΓ_s, and measure β_s in [-π/2, -1.51] U [-0.06, 0.30] U [1.26, π/2] at the 68% confidence level, in agreement with the standard model expectation. Assuming the standard model value of β_s, we also determine ΔΓ_s = 0.068 +- 0.026 (stat) +- 0.009 (syst) ps-1 and the mean B0_s lifetime, τ_s = 1.528 +- 0.019 (stat) +- 0.009 (syst) ps, which are consistent and competitive with determinations by other experiments.