Title:
Exotic never before seen particle discovered at CERN
Author:
Ben Robinson, University of Manchester
Published:
Phys.org, 1 July 2020
https://phys.org/news/2020-07-exotic-particle-cern.html
From the article:
The Large Hadron Collider Beauty (LHCb) project has observed an exotic particle made up of four charm quarks for the first time.
The LHCb collaboration has observed a type of four-quark particle never seen before. The discovery, presented at a recent seminar at CERN and described in a paper published today is likely to be the first of a previously undiscovered class of particles never before seen by physicists.
See also:
Observation of structure in the J/ψ-pair mass spectrum
Published:
arXiv, 30 June 2020
https://arxiv.org/abs/2006.16957
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/c2 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/c2, 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.