Exotic Particle Discovery Could Explain Why Matter Has Mass
Researchers have reported evidence for a new type of mesic nucleus, which could help explain why matter has mass. This discovery involves mesons, particles made of a quark and an anti-quark, bound together with an atomic nucleus. The study, published in Physical Review Letters, reveals signs of an η′-mesic nucleus, a previously unseen state. The research was conducted at the GSI Helmholtzzentrum für Schwerionenforschung in Germany, where high-energy protons were directed onto a carbon target, producing η′ mesons that became temporarily trapped inside the nucleus. 
