Observation of the $B_s^0\to \hat{I}{\cdot }^{\prime }\hat{I}{\cdot }^{\prime }$ decay

Abstract

The first observation of the $B_s^0\to \hat{I}{\cdot }^{\prime }\hat{I}{\cdot }^{\prime }$ decay is reported. The study is based on a sample of proton-proton collisions corresponding to $3.0$ $\mathrm{f}{\mathrm{b}}^{-1}$ of integrated luminosity collected with the LHCb detector. The significance of the signal is $6.4$ standard deviations. The branching fraction is measured to be $[3.31\pm 0.64(\mathrm{stat})\pm 0.28(\mathrm{syst})\pm 0.12(\mathrm{norm})]\times 10^{-5}$, where the third uncertainty comes from the $B^{\pm }\to \hat{I}{\cdot }^{\prime }{K}^{\pm }$ branching fraction that is used as a normalisation. In addition, the charge asymmetries of $B^{\pm }\to \hat{I}{\cdot }^{\prime }{K}^{\pm }$ and $B^{\pm }\to \ddot{I}•K^{\pm }$, which are control channels, are measured to be $(-0.2\pm 1.3)\%$ and $(+1.7\pm 1.3)\%$, respectively. All results are consistent with theoretical expectations.