fermiones

Fermions are particles with half-integer spin that obey Fermi-Dirac statistics. In the Standard Model, the fundamental fermions are the quarks and leptons, and together with their antiparticles they constitute the matter content of the universe. Composite particles can also be fermions if they contain an odd number of fermionic constituents, for example protons and neutrons.

A defining property of fermions is the Pauli exclusion principle: no two fermions can occupy the same quantum state. This arises from the antisymmetric nature of their wavefunctions and is a consequence of the spin-statistics theorem, which links half-integer spin to Fermi-Dirac statistics. Fermions are described by quantum field theory as fields with anticommutation relations; creation and annihilation operators for fermions anticommute, enforcing the exclusion principle. In interactions, fermions couple to gauge bosons such as photons, W and Z bosons, and gluons. In the Standard Model, quarks participate in strong interactions, while leptons do not.

The known fermions comprise six quarks (up, down, charm, strange, top, bottom) and six leptons (electron, muon, tau and their corresponding neutrinos). They appear in three generations. Fermions can be Dirac particles, with distinct antiparticles, or Majorana particles, potentially identical to their antiparticles (a possibility discussed for neutrinos). Masses arise through the Higgs mechanism; neutrino masses require additional mechanisms beyond the original Standard Model.

In physics, fermions underpin the structure of matter, influence the electronic properties of materials, and provide degeneracy pressure that supports dense astrophysical objects such as white dwarfs and neutron stars.