The first observation of exotic states with a new quark content c c ¯ u s ¯ decaying to the J /ψ K+ final state is reported with high significance from an amplitude analysis of the B+→J /ψ ϕ K+ 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, Zc s(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 /ψ ϕ final state is also observed with high significance. In addition, the four previously reported J /ψ ϕ states are confirmed and two more exotic states, Zc s(4220 )+ and X (4630 ), are observed with significance exceeding 5 standard deviations.
Physical Review Letters
- Pub Date:
- August 2021
- High Energy Physics - Experiment
- All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2020-044.html (LHCb public pages)