Measurement of the bottom-strange meson mixing phase in the full CDF data set

Abstract

We report a measurement of the bottom-strange meson mixing phase βs using the time evolution of B0s→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 √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 βs and the B0s decay-width difference ΔΓs and measure βs∈[−π/2,−1.51]∪[−0.06,0.30]∪[1.26,π/2] at the 68% confidence level, in agreement with the standard model expectation. Assuming the standard model value of βs, we also determine ΔΓs=0.068±0.026(stat)±0.009(syst) ps−1 and the mean B0s lifetime τs=1.528±0.019(stat)±0.009(syst) ps, which are consistent and competitive with determinations by other experiments.