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

LHCb collaboration, R. Aaij, C. Abellán Beteta +953

The first observation of exotic states with a new quark content $c\bar{c}u\bar{s}$ decaying to the $J/\psi K^{+}$ final state is reported with high significance from an amplitude anal…