Search for $CP$ violation in $B_s^0$ mixing at LHCb

One of the main goals of the LHCb experiment is to determine the mixing-induced $CP$ violating phase ${\varphi }_s$ in $b\to c\bar{c}s$ transitions. Assuming the Standard Model, ${\varphi }_s$ is precisely predicted, hence new physics could easily affect the measurement. The most precise single measurement using $B_s^0\to J\mathrm{/}\psi K^{+}{K}^{-}$ data collected in 2015 and 2016 is presented along with a total combined value including all LHCb ${\varphi }_s^{c\bar{c}s}$ analyses. The result is further combined with Tevatron and other LHC experimental results.