Physical Review
Rotational Invariance and the S Matrix in Nonrelativistic Quantum Mechanics
R. Fong, Joseph Sucher
Abstract
The connection between an observable invariance property of the scattering matrix and the interaction, $V$, generating the scattering, is studied for a particlar case: rotational invariance in nonrelativistic "potential" scattering. It is shown that a determination that the scattering cross section depends only on the angle between the incident and outgoing beams by no means implies that $V$ is invariant under rotation. This is true even if coherent incident beams are used to probe the target. Some aspects of these results and their relevance for the construction of physical theories are briefly discussed.