Parity inversion P amounts to the sign flip of an odd number of coordinates (reflection). A parity-symmetric theory conserves P; since P²=I, the eigenvalues of P are 1 or -1. May be also used for formally analogous global, discrete, Z₂ symmetries, such as R- or G-parity.
Parity inversion P amounts to the sign flip of an odd number of coordinates (reflection). A parity-symmetric theory conserves P, and since P²=I, the eigenvalues of P are 1 or -1: In QM, this splits eigenstates into parity- even or odd configurations. In QFT, particles have an intrinsic parity, and interactions can have their dynamics and selection rules organized and classified by conservation of parity. All interactions conserve parity except for the Electroweak ones, violating it maximally, so parity has often served as a discriminant of the weak-interaction part of a process.
