@Article{LHCbCollaborationAaij_etal2020,
author="LHCb Collaboration (Aaij, R. et al
and Garcia Martin, L. M.
and Henry, L.
and Jashal, B. K.
and Martinez-Vidal, F.
and Oyanguren, A.
and Remon Alepuz, C.
and Ruiz Vidal, J.
and Sanchez Mayordomo, C.",
title="Observation of structure in the J/psi-pair mass spectrum",
journal="Science Bulletin",
year="2020",
publisher="Elsevier",
volume="65",
number="23",
pages="1983--1993",
optkeywords="QCD; Exotics; Tetraquark; Spectroscopy; Quarkonium; Particle and resonance production",
abstract="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.",
optnote="WOS:000593153200012",
optnote="exported from refbase (https://references.ific.uv.es/refbase/show.php?record=4622), last updated on Tue, 15 Dec 2020 11:29:42 +0000",
issn="2095-9273",
doi="10.1016/j.scib.2020.08.032",
opturl="https://arxiv.org/abs/2006.16957",
opturl="https://doi.org/10.1016/j.scib.2020.08.032",
language="English"
}