Abstract
Using collision data corresponding to an integrated luminosity of recorded by the LHCb experiment at center-of-mass energies of , 8, and 13 TeV, the observation of an excited state in the invariant-mass spectrum is reported. The observed peak has a mass of , where the last uncertainty is due to the limited knowledge of the mass. It is consistent with expectations of the state reconstructed without the low-energy photon from the decay following . A second state is seen with a global (local) statistical significance of () and a mass of , and is consistent with the state. These mass measurements are the most precise to date.
- Received 29 March 2019
- Revised 23 April 2019
DOI:https://doi.org/10.1103/PhysRevLett.122.232001
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© 2019 CERN, for the LHCb Collaboration