Compact Muon Solenoid
LHC, CERN
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| CMS-PAS-BPH-24-003 | ||
| Observation of a family of all-charm tetraquark candidates at the LHC | ||
| CMS Collaboration | ||
| 7 April 2025 | ||
| Abstract: Three structures, $ \mathrm{X(6600)} $, $ \mathrm{X(6900)} $, and $ \mathrm{X(7100)} $, have been reported in the $ \mathrm{J}/\psi \, \mathrm{J}/\psi $ channel. These are prime candidates for all-charm tetraquarks. We extend our earlier study of these structures in proton-proton collisions using the CMS detector at the LHC, with 3.6 times more $ \mathrm{J}/\psi \, \mathrm{J}/\psi $ pairs (315 fb$ ^{-1} $ of total integrated luminosity). The statistical uncertainties on the masses and widths are reduced by about a factor of three, and the systematic uncertainties are also substantially reduced. For the first time all three structures are established with a significance well above five standard deviations (5$ \sigma $). Good descriptions of the $ \mathrm{J}/\psi \, \mathrm{J}/\psi $ spectrum were based on quantum interference among structures, which is now validated with significances of more than 5$ \sigma $ relative to the fit with no interference---implying all structures have the same $ J^{PC} $ quantum numbers, and suggests a family of states. | ||
| Links: CDS record (PDF) ; CADI line (restricted) ; | ||
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Compact Muon Solenoid LHC, CERN |
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