Improved measurement of $\eta /{\eta }^{\prime }$ mixing in $B_{(s)}^0\to J/\psi {\eta }^{(\prime )}$ decays

LHCb collaboration, R. Aaij, A. S. W. Abdelmotteleb +1182

Branching fraction ratios between the decays $B_{(s)}^0\to J/\psi {\eta }^{(\prime )}$ are measured using proton-proton collision data collected by the LHCb experiment at centre-of…