Measurement of the CP-violating phase ϕs from Bs0→J/ψπ+π− decays in 13 TeV pp collisions

Abstract Decays of B s 0 and B ‾ 0 s mesons into J / ψ π + π − final states are studied in a data sample corresponding to 1.9 fb−1 of integrated luminosity collected with the LHCb detector in 13 TeV pp collisions. A time-dependent amplitude analysis is used to determine the final-state resonance contributions, the CP-violating phase ϕ s = − 0.057 ± 0.060 ± 0.011 rad, the decay-width difference between the heavier mass B s 0 eigenstate and the B 0 meson of − 0.050 ± 0.004 ± 0.004 ps−1, and the CP-violating parameter | λ | = 1.01 − 0.06 + 0.08 ± 0.03 , where the first uncertainty is statistical and the second systematic. These results are combined with previous LHCb measurements in the same decay channel using 7 TeV and 8 TeV pp collisions obtaining ϕ s = 0.002 ± 0.044 ± 0.012 rad, and | λ | = 0.949 ± 0.036 ± 0.019 .