First Measurement of the CP-Violating Phase in B0s→ϕϕ Decays

Abstract

A first flavor-tagged measurement of the time-dependent C P -violating asymmetry in B 0 s → ϕ ϕ decays is presented. In this decay channel, the C P -violating weak phase arises due to C P violation in the interference between B 0 s − ¯¯¯ B 0 s mixing and the b → s ¯ s s gluonic penguin decay amplitude. Using a sample of p p collision data corresponding to an integrated luminosity of 1.0 fb − 1 and collected at a center-of-mass energy of 7 TeV with the LHCb detector, 880 B 0 s → ϕ ϕ signal decays are obtained. The C P -violating phase is measured to be in the interval [ − 2.46 , − 0.76 ] rad at a 68% confidence level. The p value of the standard model prediction is 16%.