Observation of a resonance in $B^{+}\to K^{+}{\mu }^{+}{\mu }^{-}$ decays at low recoil

LHCb collaboration, R. Aaij, B. Adeva +657

A broad peaking structure is observed in the dimuon spectrum of $B^{+}\to K^{+}{\mu }^{+}{\mu }^{-}$ decays in the kinematic region where the kaon has a low recoil against the dimuon system. The s…