In quantum mechanics, given a particular Hamiltonian and an operator with corresponding eigenvalues and eigenvectors given by , the are said to be good quantum numbers if every eigenvector remains an eigenvector of with the same eigenvalue as time evolves. In other words, the eigenvalues are good quantum numbers if the corresponding operator is a constant of motion. Good quantum numbers are often used to label initial and final states in experiments. For example, in particle colliders:
Mario Ludovico Podesta, Francesca Maria Poli, Anna Teplukhina, Matteo Vallar, Jiangyan Yang
Harald Brune, François Patthey, Stefano Rusponi, Marina Pivetta, Dante Philippe Sblendorio, Alberto Curcella