tetraquark
From ars technica, Feb. 29, 2016: Fermilab’s found a brand-new species—the first particle with four flavors of quarks.
From IFL Science, Feb. 27, 2016: Scientists on the DZero experiment have found an incredible new particle that’s part of the exotic family of tetraquarks.
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.”