LHCb discovers a new type of tetraquark

Recommendable! The subatomic particle zoo continuous to grow! What is particularly interesting here in this case is that the researchers made this discovery by sifting through historical experimental data. What else lies hidden in these data? Stay tuned! :-)

"For decades, however, theorists have predicted the existence of four-quark and five-quark hadrons, which are sometimes described as tetraquarks and pentaquarks. In recent years experiments including the LHCb have confirmed the existence of several of these exotic hadrons. ... “Particles made up of four quarks are already exotic, and the one we have just discovered is the first to be made up of four heavy quarks of the same type, specifically two charm quarks and two charm antiquarks,”  ...  “Up until now, the LHCb and other experiments had only observed tetraquarks with two heavy quarks at most and none with more than two quarks of the same type.” ... Sifting through the full LHCb datasets from the first and second runs of the Large Hadron Collider, which took place from 2009 to 2013 and from 2015 to 2018 respectively, the researchers detected a bump in the mass distribution of a pair of J/ψ particles, which consist of a charm quark and a charm antiquark."

If you just read the abstract of the underlying research paper, you would probably be forgiven not to recognize that this discovery is really significant: "... 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. ..."

LHCb discovers a new type of tetraquark | symmetry magazine

Here is the link to the underlying research paper: Observation of structure in the J/ψ-pair mass spectrum