Tagged time-dependent angular analysis of B0s→J/ψϕ decays with the 2010 LHCb data

Abstract

The interference between B0s decays to Jψϕ either directly or via B0s−B¯0s oscillation gives rise to a CP violating phase ϕJ/ψϕs. In the Standard Model, this phase is approximately -2βs, where βs = arg (-VtsV∗tb/VcsV∗cb). We have performed a measurement of ϕJψϕs using a sample that contains 836 ± 60 B0s→J/ψϕ events extracted from 36 pb−1 of pp collisions collected during the 2010 LHC run at s√ = 7 TeV. The result is presented as a two-dimensional region in the ϕs-ΔΓs plane. The probability of a fluctuation from the Standard Model expectation to the observed result for ϕs and ΔΓs is 22% (``1.2σ''). We derive a one-dimensional interval at 68% CL of ϕs∈ [-2.7, -0.5] rad.