First direct observation of the dead-cone effect in particle physics

The ALICE collaboration at the Large Hadron Collider (LHC) has made the first direct observation of the dead-cone effect—a fundamental feature of the theory of the strong force that binds quarks and gluons together into protons, neutrons and, ultimately, all atomic nuclei. In addition to confirming this effect, the observation, reported in a paper published today in Nature, provides direct experimental access to the mass of a single charm quark before it is confined inside hadrons.