Observation of a resonance in B+→K+μ +μ- decays at low recoil

The LHCb Collaboration

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A broad peaking structure is observed in the dimuon spectrum of B +→K+μ+μ- decays in the kinematic region where the kaon has a low recoil against the dimuon system. The structure is consistent with interference between the B+→K +μ+μ- decay and a resonance and has a statistical significance exceeding six standard deviations. The mean and width of the resonance are measured to be 4191-8+9 MeV/c2 and 65-16+22 MeV/c2, respectively, where the uncertainties include statistical and systematic contributions. These measurements are compatible with the properties of the ψ(4160) meson. First observations of both the decay B+→ψ (4160)K+ and the subsequent decay ψ(4160)→μ +μ- are reported. The resonant decay and the interference contribution make up 20% of the yield for dimuon masses above 3770 MeV/c2. This contribution is larger than theoretical estimates.

Original languageEnglish
Article number112003
Number of pages8
JournalPhysical Review Letters
Issue number11
Publication statusPublished - 10 Sept 2013
Externally publishedYes

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