Observation of New Resonances Decaying to J /ψK+ and J /ψφ

(LHCb Collaboration)

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120 Scopus citations


The first observation of exotic states with a new quark content cc¯us¯ decaying to the J/ψK+ final state is reported with high significance from an amplitude analysis of the B+→J/ψφK+ decay. The analysis is carried out using proton-proton collision data corresponding to a total integrated luminosity of 9 fb-1 collected by the LHCb experiment at center-of-mass energies of 7, 8, and 13 TeV. The most significant state, Zcs(4000)+, has a mass of 4003±6-14+4 MeV, a width of 131±15±26 MeV, and spin parity JP=1+, where the quoted uncertainties are statistical and systematic, respectively. A new 1+ X(4685) state decaying to the J/ψφ final state is also observed with high significance. In addition, the four previously reported J/ψφ states are confirmed and two more exotic states, Zcs(4220)+ and X(4630), are observed with significance exceeding 5 standard deviations.

Original languageEnglish (US)
Article number082001
JournalPhysical Review Letters
Issue number8
StatePublished - Aug 20 2021

ASJC Scopus subject areas

  • General Physics and Astronomy


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