 Wigner's classification

Wigner's classification obtains irreducible positive-energy representations of the Poincare group by inducing from unitary irreducible representations of the little group of a standard momentum.

Wigner's classification refers to a systematic approach to categorize the symmetries and properties of quantum systems based on the principles of group theory, particularly in the context of nuclear and particle physics. It is named after the physicist Eugene Wigner, who contributed to the understanding of symmetries in quantum mechanics. The classification typically deals with the representations of groups that describe symmetries of physical systems.