T he quarks that make up the nuclei of all atoms around us are known to "mix": the different types of quark occasionally change into one another. The amounts in which these processes happen are ...

This high-density quark behavior is called color superconductivity. The strength of pairing inside a color superconductor is difficult to calculate, but scientists have long known the strength's ...

Protons and neutrons are not, each being made of three quarks. Protons have two up quarks and one down quark, and neutrons are made of one up and two downs. However, four other types of quarks exist.