Observation of new resonances decaying to $J/ \psi K^{+}$and $J \psi\phi$

The first observation of exotic states with a new quark content ccus decaying to the $J/\psi K^{+}$ final state is reported with high significance from an amplitude analysis of the $B^{+} \to J/\psi \phi K^{+} $ decay. The analysis is carried out using proton-proton collision data corresponding to a total integrated luminosity of $9{\rm{fb}^{-1}}$ collected by the LHCb experiment at centre-of-mass energies of 7, 8 and $\rm{TeV}$ . The most significant state, $Z_{cs}(4000)^+$, has a mass of $4003\pm6^{+4}_{-14}$ MeV, a width of $131\pm15\pm26$ MeV, and spin-parity $J^{P}=1^{+}$, where the quoted uncertainties are statistical and systematic, respectively. A new $1^+$ $X(4685)$ state decaying to the $J/\psi \phi$ final state is also observed with high significance. In addition, the four previously reported $J/\psi \phi$ states are confirmed and two more exotic states, $Z_{cs}(4220)^+$ and $X(4630)$, are observed with significance exceeding five standard deviations.