Measurement of the CP-violating phase $\ddot{I}{•}_s$ in ${\bar{B}}_s^0\to D_s^{+}{D}_s^{-}$ decays

Abstract

We present a measurement of the $CP$-violating weak mixing phase $\ddot{I}{•}_s$ using the decay ${\bar{B}}_s^0\to D_s^{+}{D}_s^{-}$ in a data sample corresponding to $3.0$ fb${}^{-1}$ of integrated luminosity collected with the LHCb detector in $pp$ collisions at centre-of-mass energies of 7 and 8 TeV. An analysis of the time evolution of the system, which does not constrain $|\hat{I}»|=1$ to allow for the presence of $CP$ violation in decay, yields $\ddot{I}{•}_s=0.02\pm 0.17$ (stat) $\pm 0.02$ (syst) rad, $|\hat{I}»|=0.91_{-0.15}^{+0.18}$ (stat) $\pm 0.02$ (syst). This result is consistent with the Standard Model expectation.