Measurement of $CP$ violation in $B^0\to J/\ddot{I}ˆK_S^0$ decays

Abstract

Measurements are presented of the $CP$ violation observables $S$ and $C$ in the decays of $B^0$ and $\overline{B}{}^0$ mesons to the $J/\ddot{I}ˆK_S^0$ final state. The data sample corresponds to an integrated luminosity of $3.0{\text{fb}}^{-1}$ collected with the LHCb experiment in proton-proton collisions at center-of-mass energies of $7$ and $8\text{TeV}$. The analysis of the time evolution of $41500$ $B^0$ and $\overline{B}{}^0$ decays yields $S=0.731\pm 0.035\text{(stat)}\pm 0.020\text{(syst)}$ and $C=-0.038\pm 0.032\text{(stat)}\pm 0.005\text{(syst)}$. In the Standard Model, $S$ equals $\sin (2{\hat{I}}^2)$ to a good level of precision. The values are consistent with the current world averages and with the Standard Model expectations.

19 pages, 5 figures; updated Ref. [11]