Observation of structure in the J/ψ-pair mass spectrum

LHCb Collaboration

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Abstract

Using proton-proton collision data at centre-of-mass energies of s=7,8 and 13TeV recorded by the LHCb experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 9fb -1, the invariant mass spectrum of J/ψ pairs is studied. A narrow structure around 6.9GeV/c 2 matching the lineshape of a resonance and a broad structure just above twice the J/ψ mass are observed. The deviation of the data from nonresonant J/ψ-pair production is above five standard deviations in the mass region between 6.2 and 7.4GeV/c 2, covering predicted masses of states composed of four charm quarks. The mass and natural width of the narrow X(6900) structure are measured assuming a Breit-Wigner lineshape.

Original languageEnglish
Pages (from-to)1983-1993
Number of pages11
JournalScience Bulletin
Volume65
Issue number23
DOIs
Publication statusPublished - 15-Dec-2020

Keywords

  • DOUBLE PARTON SCATTERING
  • MATRIX-ELEMENT
  • PP COLLISIONS
  • HELAC-ONIA
  • STATES
  • DECAY
  • PENTAQUARK
  • GENERATOR
  • EVENTS
  • TOOL
  • Spectroscopy
  • Exotics
  • Quarkonium
  • Particle and resonance production
  • QCD
  • Tetraquark

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