Observation of New Resonances Decaying to J=ψK+ and J=ψφ
The first observation of exotic states with a new quark content cc ̄us ̄ decaying to the J=ψKþ final state is reported with high significance from an amplitude analysis of the Bþ → J=ψφKþ 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, Z ð4000Þþ, has a mass of 4003 6þ4 MeV, a width of 131 15 26 MeV, and spin parity cs −14 JP 1⁄4 1þ, where the quoted uncertainties are statistical and systematic, respectively. A new 1þ Xð4685Þ 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, Zcsð4220Þþ and Xð4630Þ, are observed with significance exceeding 5 standard deviations.