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

Aaij, R, Beteta, C Abellan, Adeva, B, Adinolfi, M, Aidala, CA, Ajaltouni, Z, Akar, S, Albicocco, P, Albrecht, J, Alessio, F
et al (show 834 more authors) (2020) Observation of structure in the <i>J</i>/ψ-pair mass spectrum. SCIENCE BULLETIN, 65 (23). pp. 1983-1993.

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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<sup>-1</sup>, the invariant mass spectrum of J/ψ pairs is studied. A narrow structure around 6.9GeV/c<sup>2</sup> 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<sup>2</sup>, 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.

Item Type: Article
Additional Information: All figures and tables, along with any supplementary material and additional information, are available at https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2020-011.html (LHCb public pages)
Uncontrolled Keywords: QCD, Exotics, Tetraquark, Spectroscopy, Quarkonium, Particle and resonance production
Divisions: Faculty of Science and Engineering > School of Physical Sciences
Depositing User: Symplectic Admin
Date Deposited: 21 Apr 2021 10:26
Last Modified: 17 Oct 2023 06:05
DOI: 10.1016/j.scib.2020.08.032
Open Access URL: https://www.sciencedirect.com/science/article/pii/...
Related URLs:
URI: https://livrepository.liverpool.ac.uk/id/eprint/3120048