CERN Accelerating science

Precision measurements of direct and mixing-induced $C\!P$-violating observables in neutral $B^0_s$-meson decays are amongst the most promising ways to look for signs of new physics in the flavour sector. The $C\!P$-violating phase $\phi_s$, which arises in the interference between the amplitudes of direct $B^0_s$-meson decay and the decay after oscillation in $b \to q\bar{q}s$ transitions, is particularly interesting because the Standard Model expectation for its value is both very small and precise. In this talk, an overview of the current experimental status and latest developments in this area will be presented, notably including a novel LHCb measurement of $\phi_s$ performed for the first time ever using the $B^0_s \to (K^+\pi^-)(K^-\pi^+)$ decay. This decay proceeds via a $b \to d\bar{d}s$ transition, which can only occur at loop level in the Standard Model, thus providing a sensitive probe for new physics.