Measurement of CP Violation in ${\mathrm{B}}_{\mathrm{s}}^0\text{\hspace{0.17em}⁣}\to \mathrm{J}\mathrm{/}\psi \varphi$ decays with the CMS detector

The CP-violating weak phase ${\varphi }_{\mathrm{s}}$ and the decay width difference $\mathrm{\Delta }{\mathrm{\Gamma }}_{\mathrm{s}}$ of ${\mathrm{B}}_{\mathrm{s}}^0$ mesons are measured by the CMS experiment at the LHC using a data sample of ${\mathrm{B}}_{\mathrm{s}}^0\text{\hspace{0.17em}⁣}\to \mathrm{J}\mathrm{/}\psi \varphi$ decays. The analysed dataset corresponds to an integrated luminosity of about $20{\mathrm{f}\mathrm{b}}^{-1}$ collected in $pp$ collisions at a centre-of-mass energy $\sqrt{s}=8\mathrm{T}\mathrm{e}\mathrm{V}$. A total of $49000$ reconstructed ${\mathrm{B}}_{\mathrm{s}}^0$ decays are used to extract the values ${\varphi }_{\mathrm{s}}$ and $\mathrm{\Delta }{\mathrm{\Gamma }}_{\mathrm{s}}$ by performing a time-dependent and flavour-tagged angular analysis of the ${\mu }^{+}{\mu }^{-}{\mathrm{K}}^{+}{\mathrm{K}}^{-}$ final state.The weak phase is measured to be $\phi_$\mathrm{s}$ = -0.03 \pm 0.11~$(\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t}\mathrm{.})$ \pm 0.03~$(\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}\mathrm{.})$~$\mathrm{r}\mathrm{a}\mathrm{d}$$, and the decay width difference between the ${\mathrm{B}}_{\mathrm{s}}^0$ mass eigenstates is $\Delta\Gamma_$\mathrm{s}$ = 0.096 \pm 0.014~$(\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t}\mathrm{.})$ \pm 0.007~$(\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}\mathrm{.})$~$\mathrm{p}\mathrm{s}$^{-1}$.