%0 Journal Article
%T Observation of structure in the J/psi-pair mass spectrum
%A LHCb Collaboration (Aaij, R. et al
%A Garcia Martin, L. M.
%A Henry, L.
%A Jashal, B. K.
%A Martinez-Vidal, F.
%A Oyanguren, A.
%A Remon Alepuz, C.
%A Ruiz Vidal, J.
%A Sanchez Mayordomo, C.
%J Science Bulletin
%D 2020
%V 65
%N 23
%I Elsevier
%@ 2095-9273
%G English
%F LHCbCollaborationAaij_etal2020
%O WOS:000593153200012
%O exported from refbase (https://references.ific.uv.es/refbase/show.php?record=4622), last updated on Tue, 15 Dec 2020 11:29:42 +0000
%X Using proton-proton collision data at centre-of-mass energies of root s = 7, 8 and 13 TeV recorded by the LHCb experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 9 fb(-1), the invariant mass spectrum of J/psi pairs is studied. A narrow structure around 6.9 GeV/c(2) matching the line-shape of a resonance and a broad structure just above twice the J/psi mass are observed. The deviation of the data from nonresonant J/psi-pair production is above five standard deviations in the mass region between 6.2 and 7.4 GeV/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.
%K QCD
%K Exotics
%K Tetraquark
%K Spectroscopy
%K Quarkonium
%K Particle and resonance production
%R 10.1016/j.scib.2020.08.032
%U https://arxiv.org/abs/2006.16957
%U https://doi.org/10.1016/j.scib.2020.08.032
%P 1983-1993