The LHCb experiment at CERN's Large Hadron Collider (LHC) has discovered a new particle made of two charm quarks and one down quark. Its structure is similar to that of the familiar proton, but two light up quarks are replaced by two much heavier charm quarks—making the new particle about four times heavier.
"The result will help theorists test models of quantum chromodynamics, the theory of the strong force that binds quarks into not only conventional baryons and mesons but also more exotic hadrons such as tetraquarks and pentaquarks," says LHCb Spokesperson Vincenzo Vagnoni.