Measurement of the CP-violating weak phase $ϕ_s$ and the decay width difference $ΔΓ_s$ using the $B^{0}_{s}→J/ψϕ(1020)$ decay channel in pp collisions at $\sqrt{s} = 8$ TeV

Abstract

The CP-violating weak phase $ϕ_s$ of the $B^{0}_{s}$ meson and the decay width difference $ΔΓ_s$ of the Bs0 light and heavy mass eigenstates are measured with the CMS detector at the LHC using a data sample of $B^{0}_{s}→J/ψϕ(1020)→μ^{+}μ^{−}K^{+}K^{−}$ decays. The analysed data set corresponds to an integrated luminosity of 19.7fb$^{−1}$ collected in pp collisions at a centre-of-mass energy of 8TeV . A total of 49 200 reconstructed $B^{0}_{s}$ decays are used to extract the values of $ϕ_s$ and $ΔΓ_s$ by performing a time-dependent and flavour-tagged angular analysis of the $μ^{+}μ^{−}K^{+}K^{−}$ final state. The weak phase is measured to be $ϕ_s$=−0.075±0.097(stat)±0.031(syst) rad , and the decay width difference is $ΔΓ_s$=0.095±0.013(stat)±0.007(syst) ps$^{−1}$