TY  - JOUR
AU  - LHCb Collaboration (Aaij, R. et al
AU  - Garcia Martin, L. M.
AU  - Henry, L.
AU  - Jashal, B. K.
AU  - Martinez-Vidal, F.
AU  - Oyanguren, A.
AU  - Remon Alepuz, C.
AU  - Ruiz Vidal, J.
AU  - Sanchez Mayordomo, C.
PY  - 2020
DA  - 2020//
TI  - Observation of structure in the J/psi-pair mass spectrum
T2  - Sci. Bull.
JO  - Science Bulletin
SP  - 1983
EP  - 1993
VL  - 65
IS  - 23
PB  - Elsevier
KW  - QCD
KW  - Exotics
KW  - Tetraquark
KW  - Spectroscopy
KW  - Quarkonium
KW  - Particle and resonance production
AB  - 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.
SN  - 2095-9273
UR  - https://arxiv.org/abs/2006.16957
UR  - https://doi.org/10.1016/j.scib.2020.08.032
DO  - 10.1016/j.scib.2020.08.032
LA  - English
N1  - WOS:000593153200012
ID  - LHCbCollaborationAaij_etal2020
ER  -