Fermions are identical particles whose total multiparticle state is antisymmetric under exchange. In three-dimensional relativistic quantum theory they have half-integer spin.
For two identical spin-one-half fermions with no additional antisymmetric internal factor, the antisymmetric spin-one-half singlet state combines with an even- symmetric orbital state, while the symmetric spin-one-half triplet state combines with an odd- antisymmetric orbital state.
No two identical fermions may occupy the same one-particle quantum state. At zero temperature, noninteracting fermions fill the available one-particle states in increasing order of energy.
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A fermion is a type of elementary particle that follows Fermi-Dirac statistics and obeys the Pauli exclusion principle. Fermions have half-integer spins (e.g., 1/2, 3/2) and include particles like quarks and leptons. In the context of particle physics, the most well-known examples of fermions are: 1. **Quarks**: Fundamental constituents of protons and neutrons.
