In the presence of New Physics phenomena, sources of $CP$ violation can arise in addition to those
predicted by the Standard Model.
The $B_s^0\rightarrow J/\psi \phi $ decay can provide a very precise measurement of the $CP$-violating phase $\phi_s$, the decay width $\Gamma_s$ and the difference of widths between the mass eigenstates $\Delta \Gamma_s$.
Results presented here use data of $pp$ collisions at $\sqrt{s}$ = 13 TeV corresponding to 80.5 fb$^{-1}$ of integrated luminosity collected by ATLAS at the Large Hadron Collider in years 2015--2017, and are statistically combined with the previous measurements with 19.2~fb$^{-1}$ data with 7 and 8~TeV energy leading to
\begin{align*}
\phi_s &= -0.087 \pm 0.036 \textrm{ (stat.)} \pm 0.021 \textrm{ (syst.)}\\
\Gamma_s &= 0.6703 \pm 0.0014 \textrm{ (stat.)} \pm 0.0018 \textrm{ (syst.)}\\
\Delta\Gamma_s &= 0.0657 \pm 0.0043 \textrm{ (stat.)} \pm 0.0037 \textrm{ (syst.)}.\\
\end{align*}