Observation of an Excited Bc+ State

LHCb Collaboration

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Using pp collision data corresponding to an integrated luminosity of 8.5 fb-1 recorded by the LHCb experiment at center-of-mass energies of √s=7, 8, and 13 TeV, the observation of an excited Bc+ state in the Bc+π+π- invariant-mass spectrum is reported. The observed peak has a mass of 6841.2±0.6(stat)±0.1(syst)±0.8(Bc+) MeV/c2, where the last uncertainty is due to the limited knowledge of the Bc+ mass. It is consistent with expectations of the Bc(23S1)+ state reconstructed without the low-energy photon from the Bc(13S1)+→Bc+γ decay following Bc(23S1)+→Bc(13S1)+π+π-. A second state is seen with a global (local) statistical significance of 2.2σ (3.2σ) and a mass of 6872.1±1.3(stat)±0.1(syst)±0.8(Bc+) MeV/c2, and is consistent with the Bc(21S0)+ state. These mass measurements are the most precise to date.

Original languageEnglish
Article number232001
Number of pages10
JournalPhysical Review Letters
Issue number23
Early online date11 Jun 2019
Publication statusPublished - 14 Jun 2019

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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