Measurement of the CP-violating weak phase phi-s and the decay width difference DeltaGamma-s using the Bs to J/psiPhi(1020) decay channel

The CP-violating weak phase $\phi_\mathrm{s}$ and the decay width difference $\Delta\Gamma_\mathrm{s}$ of $\mathrm{B_s}$ mesons are measured by the CMS experiment at the LHC using a data sample of ${\mathrm{B_s}\! \to\! \mathrm{J}/\psi(\mu^+ \mu^-)\phi(\mathrm{K^+K^-})}$ decays. The analysed dataset corresponds to an integrated luminosity of about $20~\mbox{fb}^{-1}$ collected in $\textrm{pp}$ collisions at a centre-of-mass energy $\sqrt{s}= \!8~\textrm{TeV}$. A total of $49\,000$ reconstructed $\mathrm{B_s}$ decays are used to extract the values $\phi_\mathrm{s}$ and $\Delta\Gamma_\mathrm{s}$ by performing a time-dependent and flavour-tagged angular analysis of the $\mu^+ \mu^- \mathrm{K^+K^-}$ final state. The weak phase is measured to be $\phi_\mathrm{s} = -0.03 \pm 0.11~\mathrm{(stat.)} \pm 0.03~\mathrm{(syst.)}~\mathrm{rad}$, and the decay width difference between the $\mathrm{B_s}$ mass eigenstates is $\Delta\Gamma_\mathrm{s} = 0.096 \pm 0.014 ~\mathrm{(stat.)} \pm 0.007~\mathrm{(syst.)}~\mathrm{ps}^{-1}$.