UC Berkeley

A measurement of the Bs0→J/ψϕ$$ B_{s}^{0} \rightarrow J/\psi \phi $$ decay parameters using 80.5fb-1$$ 80.5\, \mathrm {fb^{-1}} $$ of integrated luminosity collected with the ATLAS detector from 13 Te$$\text {Te}\text {V}$$ proton–proton collisions at the LHC is presented. The measured parameters include the CP-violating phase ϕs$$\phi _{s} $$, the width difference ΔΓs$$ \Delta \Gamma _{s}$$ between the Bs0$$B_{s}^{0}$$ meson mass eigenstates and the average decay width Γs$$ \Gamma _{s}$$. The values measured for the physical parameters are combined with those from 19.2fb-1$$ 19.2\, \mathrm {fb^{-1}} $$ of 7 and 8 Te$$\text {Te}\text {V}$$ data, leading to the following: ϕs=-0.087±0.036(stat.)±0.021(syst.)radΔΓs=0.0657±0.0043(stat.)±0.0037(syst.)ps-1Γs=0.6703±0.0014(stat.)±0.0018(syst.)ps-1$$\begin{aligned} \phi _{s}= & {} -0.087 \pm 0.036 ~\mathrm {(stat.)} \pm 0.021 ~\mathrm {(syst.)~rad} \ \Delta \Gamma _{s}= & {} 0.0657 \pm 0.0043 ~\mathrm {(stat.)}\pm 0.0037 ~\mathrm {(syst.)~ps}^{-1} \ \Gamma _{s}= & {} 0.6703 \pm 0.0014 ~\mathrm {(stat.)}\pm 0.0018 ~\mathrm {(syst.)~ps}^{-1} \end{aligned}$$Results for ϕs$$\phi _{s} $$ and ΔΓs$$ \Delta \Gamma _{s}$$ are also presented as 68% confidence level contours in the ϕs$$\phi _{s} $$–ΔΓs$$ \Delta \Gamma _{s}$$ plane. Furthermore the transversity amplitudes and corresponding strong phases are measured. ϕs$$\phi _{s} $$ and ΔΓs$$ \Delta \Gamma _{s}$$ measurements are in agreement with the Standard Model predictions.