CORRELATION OF PARTICLE MOMENTA IN QUANTUM-MECHANICAL SYSTEMS

Correlations of particle momenta in quantum-mechanical systems are stu died by considering the expectation values of the cross products of th ese momenta. Relations between the expectation values of the cross pro ducts and squares of particle momenta are derived. In the case of thre e-particle systems and N-particle systems involving (N - 1) identical particles, these relations make it possible to express the expectation values of the cross products of particle momenta in terms of the expe ctation values of their squares. The expectation values of the cross p roducts of particle momenta are calculated for three-particle systems with two identical particles from the atomic hydrogen ion H- to the po sitronium ion e(-)e(-)e(+); for various three-particle systems involvi ng nuclei of helium isotopes, antihydrogen nuclei, muons, and electron s; for various excited states of various three-particle mesic molecule s; and for the ground state of the lithium atom.