FERMIONS

In particle physics, fermions are particles that obey Fermi–Dirac statistics. They are named after Enrico Fermi. In contrast to bosons, which obey Bose–Einstein statistics, only one fermion can occupy a quantum state at a given time.

If more than one fermion occupies the same place in space, at least one other property for each fermion, e.g., its spin, must be different from the rest. Fermions are usually associated with matter while bosons are often force carrier particles, though the distinction between the two concepts in quantum physics is unclear.

A fermion can be an elementary particle, like the electron, or a composite particle, like the proton. The spin-statistics theorem states that in any reasonable relativisticquantum field theory particles with integer spin are bosons, while particles withhalf-integer spin are fermions.

The Standard Model recognizes two types of elementary fermions: quarks andleptons. In total, the model distinguishes 24 different fermions: 6 quarks and 6 leptons, each with a corresponding antiparticle.

Composite fermions, such as protons and neutrons, are essential building blocks of matter. Weakly interacting fermions can also display bosonic behavior, as insuperconductivity.