First study of the CP-violating phase and decay-width difference in B[superscript 0][subscript s] → ψ(2S)φ decays

A time-dependent angular analysis of B[superscript 0][subscript s] →ψ(2S)ϕ decays is performed using data recorded by the LHCb experiment. The data set corresponds to an integrated luminosity of 3.0fb[superscript −1] collected during Run 1 of the LHC. The CP-violating phase and decay-width difference of the B[superscript 0][subscript s] system are measured to be ϕs =0.23 [subscript −0.28][superscript +0.29] ± 0.02rad and ΔΓ[subscript s] =0.066 [subscript −0.044][superscript +0.041] ± 0.007ps[superscript −1], respectively, where the first uncertainty is statistical and the second systematic. This is the first time that ϕ s and ΔΓ[subscript s] have been measured in a decay containing the ψ(2S) resonance.National Science Foundation (U.S.