This work reviews recent achievements in the understanding of highly excited, interacting few-particle systems with a well defined internal helicity. To contrast theory with experiments we consider specifically the spectrum of two interacting continuum electrons with a positive (or a negative) chirality that move in the field of a positive ion. This doubly excited state is achieved upon the absorption of a circular photon with the appropriate helicity by an isotropic target. The dependence of the two-electron spectrum on the sign of the helicity of the exciting photon is utilized to study internal phase relations and mirror-reflection symmetries of the two-electron wave function.