Exotic four-quark particle spotted at Large Hadron Collider

Scientists using the Large Hadron Collider (LHC) — which memorably revealed the Higgs boson in 2012 — have discovered a previously unknown exotic particle made of four quarks. The new ‘tetraquark’, Tcc+, is extremely unusual: most known hadrons, including protons and neutrons, are made of two or three quarks. This brings the LHC’s bounty of new hadrons — non-elementary particles that are made of quarks — up to 62.