fermion

noun

1. (particle)Any elementary or composite particle that has half-integer spin and thus obeys Fermi–Dirac statistics and the Pauli exclusion principle (equivalently, a particle for which the wavefunction of any system of identical such particles changes sign whenever two are swapped); a baryon, a lepton or a quark;

   “The fermions treated by the Standard Model are the (composite) baryons and the (elementary) leptons and quarks.”

   “According to the spin–statistics theorem, the wavefunction of a system of identical fermions (particles of half-integer spin) is antisymmetric under the operation of swapping any two particles.”

   “A remarkable feature of lattice regularization is the appearance of several fermion species per fermion field in the lattice action.”

   “For 2D systems, going beyond first order pertu[r]bative calculations, we show that the second harmonic of the current is strongly suppressed in the case of spinless fermion models but significantly enhanced for the Hubbard model.”

   “It is not known whether the Higgs mechanism is the true source for the masses of the fundamental fermions.”

2. (particle)Any elementary or composite particle that has half-integer spin and thus obeys Fermi–Dirac statistics and the Pauli exclusion principle (equivalently, a particle for which the wavefunction of any system of identical such particles changes sign whenever two are swapped); a baryon, a lepton or a quark; (slightly more loosely) any such particle or any composite particle composed of fermions.