Observation of exotic $J\mathrm{/}\psi \phi$ resonant structure in diffractive processes in proton-proton collisions

The first study of $J\mathrm{/}\psi \phi$ production in diffractive processes in proton-proton collisions is presented. The study is based on an LHCb dataset recorded at centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5 fb${}^{-1}$. The data disfavour a nonresonant $J\mathrm{/}\psi \phi$ production but are consistent with a resonant model including several resonant states observed previously only in $B^{+}\to J\mathrm{/}\psi \phi K^{+}$ decays. The ${\chi }_{c0}(4500)$ state is observed with a significance over $6\sigma$ and the ${\chi }_{c1}(4274)$ is confirmed with a significance of more than $4\sigma$.