Hadrons count among their number the familiar protons and neutrons that make up our atoms, but they are much more than that.
quarks
From Quanta Magazine, May 6, 2020: Two ways of approximating the ultracomplicated math that governs quark particles have recently come into conflict, leaving physicists unsure what their decades-old theory predicts. Fermilab scientists Andreas Kronfeld and Chris Polly weigh in.
A re-examination of a particle discovered in 2015 has scientists debating its true identity. A recent analysis by the LHCb collaboration at CERN raises questions about the identity of this pentaquark—and may have taken scientists back to square one in the search for a particle that could shed light on questions about color.
From Live Science, Feb. 5, 2019: This article dives deep into the little teensy tiny particles that are fundamental building blocks of matter. As far as scientists can tell, quarks themselves are not made of anything smaller. That may change in the future as we learn more, but it’s good enough for now.
From ars technica, Feb. 29, 2016: Fermilab’s found a brand-new species—the first particle with four flavors of quarks.
From Scientific American, Feb. 26, 2016: Evidence for a never-before-seen particle containing four types of quark has shown up in data from the Tevatron collider at Fermilab.
From Gizmodo, Feb. 25, 2016: Physicists from the DZero collaboration have announced the discovery of a new particle, believed to be part of an exotic family called “tetraquarks.”
DZero announces the newest member of the tetraquark family.
Three-quark particle contains one quark from each family.
An article to appear in the February 9 issue of Science describes results contained in a paper submitted to Physical Review Letters by the 450-member Collider Detector at Fermilab collaboration.