Updated measurement of time-dependent 𝐶𝑃-violating observables in 𝐵0𝑠→𝐽/𝜓𝐾+𝐾− decays
The decay-time-dependent 𝐶𝑃CP asymmetry in 𝐵0𝑠→𝐽/𝜓𝐾+𝐾−Bs0→J/ψK+K− decays is measured using proton–proton collision data, corresponding to an integrated luminosity of 1.9fb−11.9fb−1, collected with the LHCb detector at a centre-of-mass energy of 13TeV13TeV in 2015 and 2016. Using a sample of approximately 117 000 signal decays with an invariant 𝐾+𝐾−K+K− mass in the vicinity of the 𝜙(1020)ϕ(1020) resonance, the 𝐶𝑃CP-violating phase 𝜙𝑠ϕs is measured, along with the difference in decay widths of the light and heavy mass eigenstates of the 𝐵0𝑠Bs0-𝐵⎯⎯⎯⎯0𝑠B¯s0 system, ΔΓ𝑠ΔΓs. The difference of the average 𝐵0𝑠Bs0 and 𝐵0B0 meson decay widths, Γ𝑠−Γ𝑑Γs−Γd, is determined using in addition a sample of 𝐵0→𝐽/𝜓𝐾+𝜋−B0→J/ψK+π− decays. The values obtained are 𝜙𝑠=−0.083±0.041±0.006radϕs=−0.083±0.041±0.006rad, ΔΓ𝑠=0.077±0.008±0.003ps−1ΔΓs=0.077±0.008±0.003ps−1 and Γ𝑠−Γ𝑑=−0.0041±0.0024±0.0015ps−1Γs−Γd=−0.0041±0.0024±0.0015ps−1, where the first uncertainty is statistical and the second systematic. These are the most precise single measurements of these quantities to date and are consistent with expectations based on the Standard Model and with a previous LHCb analysis of this decay using data recorded at centre-of-mass energies 7 and 8 TeV. Finally, the results are combined with recent results from 𝐵0𝑠→𝐽/𝜓𝜋+𝜋−Bs0→J/ψπ+π− decays obtained using the same dataset as this analysis, and with previous independent LHCb results.