First measurement of the CP-violating phase in $B_s^0\to \ddot{I}•\ddot{I}•$ decays

Abstract

A first flavour-tagged measurement of the time-dependent CP-violating asymmetry in $B_s^0\to \ddot{I}•\ddot{I}•$ decays is presented. In this decay channel, the CP-violating weak phase arises due to CP violation in the interference between $B_s^0$-${\bar{B}}_s^0$ mixing and the $b\to s\bar{s}s$ gluonic penguin decay amplitude. Using a sample of $pp$ collision data corresponding to an integrated luminosity of $1.0f{b}^{-1}$ and collected at a centre-of-mass energy of $7\mathrm{TeV}$ with the LHCb detector, $880\ \B_s^0 \to ϕϕ$ signal decays are obtained. The CP-violating phase is measured to be in the interval [-2.46, -0.76] \rm rad$ at 68% confidence level. The p-value of the Standard Model prediction is 16%.

9 pages, 3 figures