New Structures in the 𝐽/𝜓⁢𝐽/𝜓 Mass Spectrum in Proton-Proton Collisions at √𝑠=13  TeV

A search is reported for near-threshold structures in the J=psi J=psi invariant mass spectrum produced in proton-proton collisions at ffiffi s p 1/4 13 TeV from data collected by the CMS experiment, corresponding to an integrated luminosity of 135 fb-1. Three structures are found, and a model with quantum interference among these structures provides a good description of the data. A new structure is observed with a local significance above 5 standard deviations at a mass of 6638 thorn 43 -38 ostat thorn thorn 16 -31 osyst thorn MeV. Another structure with even higher significance is found at a mass of 6847 thorn 44 -28 ostat thorn thorn 48 -20 osyst thorn MeV, which is consistent with the Xo6900 thorn resonance reported by the LHCb experiment and confirmed by the ATLAS experiment. Evidence for another new structure, with a local significance of 4.7 standard deviations, is found at a mass of 7134 thorn 48 -25 ostat thorn thorn 41 -15 osyst thorn MeV. Results are also reported for a model without interference, which does not fit the data as well and shows mass shifts up to 150 MeV relative to the model with interference