$\mathcal{CP}$ violating phase $\phi_s$ and penguin pollution in $B_s^0\to J/\psi K^+K^-$ with LHCb

CP violating phase φs appears in b → anti(c)cs transitions due to the interference between the direct decay and the decay after the Bs⁰-anti(Bs⁰) mixing. In SM, φs = -2βs + δP, where -2βs is related to CKM matrix elements and δP is the penguin phase where contributions due to penguin diagrams are taken into account, being this δP phase also the main source of theoretical uncertainty in φs. This φs phase is very sensitive to possible NP (new particles contributing to box diagrams during the mixing, several possible BSM scenarios are presented), so δP should be estimated in order to disentangle these penguin pollution contributions from possible NP contributions, φs(LHCb) = -2βs + δP + δNP. The decay Bs⁰ → J/ψ K⁺K⁻ is a golden decay for φs measurement: latest LHCb combined result also including Bs⁰ → J/ψ π⁺π⁻ measurements is φs = -0.010 ± 0.039 rad, which is in excellent agreement with SM. The penguin pollution phase δP can be estimated using B⁰ → J/ψ ρ⁰ and Bs⁰ → J/ψ anti(K*⁰) decay channels separately: measurement in B⁰ → J/ψ ρ⁰ decay is |δP| < 0.02 rad at 95% CL. Measurement in Bs⁰ → J/ψ anti(K*⁰) decay channel is still ongoing.